Incidence of Staphylococcus aureus Bacteremia in Patients Following Implantation of Cardiac Implantable Electronic Devices: A Danish Nationwide Cohort Study.

Background: Staphylococcus aureus bacteremia (SAB) is a high-risk condition associated with high morbidity and mortality. In the presence of cardiac implantable electronic devices (CIEDs), SAB may cause or clinically indicate device infection. We aimed to estimate the 10-year absolute risk of SAB in adult Danish first-time CIED carriers. Secondary aims included identification of risk factors associated with SAB. Methods: A registry-based study utilizing Danish nationwide registers and including consecutive Danish patients undergoing first CIED implantation between 2000 and 2020 was conducted. The primary outcome was first-time SAB after CIED implantation. Results: A total of 87 257 patients with first CIED implantation in the study period were identified (median age, 75 years; 62.6% were male; median follow-up, 3.8 years). Patients with pacemakers (PMs) were older and with more noncardiovascular comorbidities compared to patients with implantable cardioverter defibrillators (ICDs) and cardiac resynchronization therapy devices with or without defibrillator capacity (CRTs). In total, 1366 patients (1.6%) developed SAB. The 10-year absolute risk (95% confidence interval) of SAB was 2.0% (1.9%-2.1%) for PM, 2.6% (2.2%-3.1%) for ICD, and 3.7% (3.0%-4.5%) for CRT. A multivariable Cox analysis identified hemodialysis (hazard ratio [HR], 8.51), SAB before CIED (HR, 2.76), liver disease (HR, 2.35), and carrying a CRT device (HR, 1.68) among the covariates associated with increased risk of SAB. Conclusions: The absolute risk of SAB in Danish CIED carriers increased with more advanced CIED systems. The risk was highest within the first 3 months after CIED implantation and increased with the presence of certain covariates including renal dialysis, SAB before CIED, male sex, and advancing age.

Effects of atrial fibrillation screening according to thyroid function: Post-hoc analysis of the randomized LOOP study.

PURPOSE: Subclinical thyroid dysfunction is a marker for atrial fibrillation (AF) and stroke risk. This study explored the effects of AF screening according to thyroid-stimulating hormone (TSH) levels. METHODS: An AF screening trial (the LOOP study) was analyzed post-hoc according to baseline TSH. The primary outcome was stroke or systemic embolism (SE). Secondary outcomes included major bleeding, all-cause death, and the combination of stroke, SE, and cardiovascular death. RESULTS: TSH measurement was available in 6003 of 6004 trial participants, 1500 randomized to implantable loop recorder (ILR) screening for AF and anticoagulation upon detection vs. 4503 to usual care; mean age was 74.7±4.1 years and 2836 (47%) were women. AF detection was approximately triple for ILR vs usual care across TSH tertiles (adjusted p-interaction=0.44). In the first tertile, screening was associated with decreased risk of the primary outcome (hazard ratio 0.52 [0.30-0.90]; p=0.02) and stroke, SE, or cardiovascular death (hazard ratio 0.54 [0.34-0.84]; p=0.006) compared to usual care, while no effect was observed among participants with higher TSH (adjusted p-interaction 0.03 and 0.01, respectively). There was no effect on other outcomes. Analyses of continuous TSH or excluding those with abnormal TSH or thyroid medication showed similar results. CONCLUSION: AF screening and subsequent treatment was associated with decreased stroke risk among participants with low TSH, though the yield of screening was similar across TSH levels. TSH may be useful as a marker to indicate benefit from AF screening vs. overdiagnosis and overtreatment. These findings should be considered exploratory and warrant further study. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT0203645.

Heart Failure Events After Long-term Continuous Screening for Atrial Fibrillation: Results From the Randomized LOOP Study.

BACKGROUND: Mounting evidence indicates that even device-detected subclinical atrial fibrillation is associated with a higher risk of heart failure (HF). However, the potential impact of atrial fibrillation screening on HF remains unknown. METHODS: The LOOP Study (Atrial Fibrillation detected by Continuous ECG Monitoring using Implantable Loop Recorder to prevent Stroke in High-risk Individuals) evaluated the effects of atrial fibrillation screening on stroke prevention using an implantable loop recorder (ILR) versus usual care in older individuals with additional stroke risk factors. In this secondary analysis, we explored the following HF end points: (1) HF event or cardiovascular death; (2) HF event; (3) event with HF with reduced ejection fraction (HFrEF); and (4) HFrEF event or cardiovascular death. Outcomes were assessed in a Cox model both as time-to-first events and as total (first and recurrent) events analyzed using the Andersen-and-Gill method. RESULTS: Of 6004 participants (mean age 74.7 and 52.7% men), 1501 were randomized to ILR screening and 4503 to the control group. In total, 77 (5.1%) in the ILR group versus 295 (6.6%) in the control group experienced the primary outcome of an HF event or cardiovascular death. Compared with usual care, ILR screening was associated with a nonsignificant reduction in the primary outcome for the time-to-first event analysis (hazard ratio, 0.78 [95% CI, 0.61-1.01]) and the total event analysis (hazard ratio, 0.77 [95% CI, 0.59-1.01]). Similar results were obtained for the HF event. A significant risk reduction in total events was observed in the ILR group for the composite of HFrEF event or cardiovascular death and for HFrEF event (hazard ratio, 0.74 [95% CI, 0.56-0.98] and 0.65 [95% CI, 0.44-0.97], respectively). CONCLUSIONS: In an older population with additional stroke risk factors, ILR screening for atrial fibrillation tended to be associated with a lower rate of total HF events and cardiovascular death, particularly those related to HFrEF. These findings should be considered hypothesis-generating and warrant further investigation. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02036450.

Long-term Rate of Ventricular Arrhythmia in Autoimmune Disease.

AIMS: Although selected autoimmune diseases (AIDs) have been linked to an increased risk of ventricular arrhythmias (VAs), data on the long-term rate of VAs across the spectrum of AIDs are lacking. The aim of our study was to investigate the long-term rate of VAs (a composite of ventricular tachycardia, ventricular fibrillation, ventricular flutter, or cardiac arrest) in individuals with a history of 28 different AIDs. METHODS: Individuals diagnosed with an AID (2005-2018) were identified through Danish nationwide registries. Each patient with AID was matched with four individuals from the background population by age and sex. Multivariable Cox regression was used to compare the rate of VAs between the AIDs and background population, overall and according to individual AIDs. RESULTS: In total, 186,733 patients diagnosed with AIDs were matched with 746,932 individuals without AIDs (median age 55 years; 63% female; median follow-up 6.0 years). The 5-year cumulative incidence of VAs was 0.5% for patients with AIDs and 0.3% for matched individuals. Patients with any AIDs had a higher associated rate of VAs than matched individuals (HR 1.39 [95% CI, 1.29-1.49]). The highest HR was observed in patients with systemic sclerosis (3.86 [95% CI, 1.92-7.75]). The higher rate of VAs in patients with AIDs, compared with individuals from the background population, was more pronounced in patients without ischemic heart disease or heart failure/cardiomyopathy compared to those with these conditions (Pinteraction < 0.05). CONCLUSIONS: Despite a low cumulative incidence, patients with a history of AIDs had a higher relative rate of VAs than matched individuals.

In a large Danish nationwide study, we examined the risk of ventricular arrhythmias, which are serious and potentially life-threatening conditions, in patients with and without a history of autoimmune diseases. Patients with a history of any autoimmune disease had a higher risk of experiencing ventricular arrhythmias compared with age- and sex-matched individuals from the background population. This association was observed for most of the autoimmune diseases when examined individually. The higher rate of ventricular arrhythmias in patients with autoimmune diseases, compared with individuals from the background population, was relatively more pronounced in patients without a history of ischemic heart disease or heart failure/cardiomyopathy compared with individuals with a history of these conditions.

Left Atrial Strain Predicts Subclinical Atrial Fibrillation Detected by Long-term Continuous Monitoring in Elderly High-Risk Individuals.

BACKGROUND: Left atrial (LA) speckle tracking provides detailed information on atrial function. Its utility for predicting subclinical atrial fibrillation (SCAF) is unclear. Therefore, we sought to investigate whether LA strain measures could predict SCAF detected by long-term continuous rhythm monitoring. METHODS: This was an echocardiographic substudy of the LOOP study, where elderly at risk of stroke were randomized to receive a loop recorder (Reveal LINQ) or control. Participants who received a loop recorder were included in this analysis. Echocardiography included LA reservoir, conduit, and contraction strain. Participants were followed with continuous rhythm monitoring for SCAF (≥6 minutes). Cox proportional hazards regression was applied to adjust for atrial fibrillation risk factors. RESULTS: In total, 956 participants were eligible for analysis. Median continuous rhythm monitoring was 35 months (IQR, 20-40 months), during which 278 (29%) were diagnosed with SCAF. The mean age was 74 years, 56% were male, median CHA2DS2-VASc-score was 4. LA reservoir strain was an independent predictor of SCAF after multivariable adjustments (HR, 1.04 [1.02-1.05], per 1% decrease) and so was contraction strain. The findings were unchanged in competing risk analyses and in participants with normal LA size and diastolic function. Participants with low reservoir strain (<33%) had a significantly higher risk of SCAF compared with those with high reservoir strain (incidence rate, 14.5 [12.4-16.9] versus 9.8 [8.2-11.8] events/100 person-years). The same was noted for low versus high contraction strain. CONCLUSIONS: LA reservoir and contraction strain are independent predictors of SCAF in elderly at risk of stroke. This also applies to individuals with normal LA size and diastolic function. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02036450.

The ABC-Stroke Risk Score and Effects of Atrial Fibrillation Screening on Stroke Prevention: Results From the Randomized LOOP Study.

BACKGROUND: The ABC-stroke score is a risk scheme for prediction of stroke or systemic embolism (SE) in atrial fibrillation (AF). This study sought to examine whether the score could be useful in predicting stroke in AF-naïve individuals and risk stratifying for AF screening. METHODS AND RESULTS: The LOOP (Atrial Fibrillation Detected by Continuous ECG Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-Risk Individuals) study randomized 6004 AF-naïve individuals aged 70 to 90 years with stroke risk factors to either screening with an implantable loop recorder and anticoagulation upon detection of new-onset AF episodes ≥6 minutes, or usual care. A total of 5781 participants had available ABC-stroke score at baseline and were included in this secondary analysis: 4170 (72.1%) with an estimated stroke/SE risk ≤1%/year versus 1611 (27.9%) with an estimated stroke/SE risk >1%/year. Having an annual ABC-stroke risk >1% was associated with stroke/SE, stroke/SE/cardiovascular death, and all-cause death (hazard ratio, 1.82 [95% CI, 1.44-2.21], 2.17 [95% CI, 1.80-2.62], and 2.19 [95% CI, 1.87-2.56], respectively). For screening with implantable loop recorder versus usual care, no significant reduction in these study outcomes was obtained in any ABC-stroke risk groups (P>0.0500 for all), with no signal toward interaction (Pinteraction>0.2500 for all). Similar findings were yielded when assessing the ABC-stroke score as a continuous variable. CONCLUSIONS: In an elderly, AF-naïve population with additional stroke risk factors, a higher ABC-stroke score could identify individuals with increased stroke risk. However, this risk score may not be useful in pinpointing those more likely to benefit from AF screening and subsequent preventive treatment. These findings should be considered as hypothesis generating and warrant further study. REGISTRATION: URL: https://www.clinicaltrials.gov; unique identifier: NCT02036450.

Anticoagulation-Associated Bleeding in Patients Screened for Atrial Fibrillation versus Usual Care-A Post Hoc Analysis from the LOOP Study.

Background Atrial fibrillation (AF) prevalence is rising; however, data on the bleeding risks associated with the detection of subclinical AF are needed. Objective Our objective was to determine the bleeding increment associated with implantable loop recorder (ILR) screening for subclinical AF and subsequent anticoagulation initiation compared with usual care. Methods This post hoc study utilized LOOP trial data from 6,004 elderly patients with stroke risks randomized to either ILR ( n = 1,503) or usual care ( n = 4,503). The mean follow-up time was 64.5 months, and none were lost to follow-up. The primary exposure was the initiation of oral anticoagulation, and the main outcome was the risk of major bleeding events following initiation of oral anticoagulants (OACs), determined by time-dependent cox regression. Second, we investigated antithrombotic prescription patterns and major bleeding events after antiplatelet treatment and in subgroups. Results OAC was initiated in 1,019 participants with a mean age (years) of 78.8 (± 4.67) in control versus 77.0 (± 4.84) in ILR, p < 0.0001. Altogether did 202 participants end or pause OAC treatment. Among AF patients (n = 910) had 40 (28%) completely ended OAC and 105 (72%) temporarily paused OAC during follow-up. Major bleeding events totaled 221 (3.7%). Forty-seven major bleeding events followed an OAC initiation in 1,019 participants (4.6%); 26 versus 21 events in the control and ILR groups, respectively. The hazard ratio (HR) for major bleeding after OAC initiation compared with before initiation was 2.08 (1.50-2.90) p < 0.0001 overall, 2.81 (1.82-4.34) p < 0.0001 for control and 1.32 (0.78-2.23) p = 0.31 for the ILR group ( p = 0.07 for interaction). Antiplatelet treatment resulted in an overall adjusted HR of 1.3 (0.96-1.75) p = 0.09. For OAC users aged ≥75 years in the ILR group, the rate of major bleeding was 1.73 (0.92-2.96) compared with 0.84 (0.36-1.66) for an age <75 years, and the rate of the corresponding control subgroup aged ≥75 years was 2.20 (1.23-3.63) compared with 1.64 (0.82-2.93) for an age <75 years. Conclusion The individual risk of major bleeding increased twofold after initiation of oral anticoagulation for all patients in this study. However, the patients screened for subclinical AF did not have a higher bleeding risk after initiation of anticoagulation compared with those in usual care. Trial Registration: The LOOP study is registered at ClinicalTrials.gov, identifier: NCT020364 50.

Epicardial adipose tissue and subclinical incident atrial fibrillation as detected by continuous monitoring: a cardiac magnetic resonance imaging study.

Epicardial adipose tissue (EAT) has endocrine and paracrine functions and has been associated with metabolic and cardiovascular disease. This study aimed to investigate the association between EAT, determined by cardiac magnetic resonance imaging (CMR), and incident atrial fibrillation (AF) following long-term continuous heart rhythm monitoring by implantable loop recorder (ILR). This study is a sub-study of the LOOP study. In total, 203 participants without a history of AF received an ILR and underwent advanced CMR. All participants were at least 70 years of age at inclusion and had at least one of the following conditions: hypertension, diabetes, previous stroke, or heart failure. Volumetric measurements of atrial- and ventricular EAT were derived from CMR and the time to incident AF was subsequently determined. A total of 78 participants (38%) were diagnosed with subclinical AF during a median of 40 (37-42) months of continuous monitoring. In multivariable Cox regression analyses adjusted for age, sex, and various comorbidities, we found EAT indexed to body surface area to be independently associated with the time to AF with hazard ratios (95% confidence intervals) up to 2.93 (1.36-6.34); p = 0.01 when analyzing the risk of new-onset AF episodes lasting ≥ 24 h. Atrial EAT assessed by volumetric measurements on CMR images was significantly associated with the incident AF episodes as detected by ILR.

Electrocardiographic Morphology-Voltage-P-Wave-Duration (MVP) Score to Select Patients for Continuous Atrial Fibrillation Screening to Prevent Stroke.

Morphology-voltage-P-wave-duration (MVP) score combining P-wave duration (PWD), P-wave voltage in lead I (PWVI), and interatrial block (IAB) has been demonstrated to predict atrial fibrillation (AF). Therefore, this study aimed to examine MVP score and its P-wave components as potential predictors of AF screening effects on stroke prevention. This was a secondary analysis of the LOOP Study (Atrial Fibrillation detected by Continuous ECG Monitoring using Implantable Loop Recorder to prevent Stroke in High-risk Individuals) which randomized older persons (aged 70 to 90 years) with additional stroke risk factors to either continuous monitoring with implantable loop recorder and anticoagulation upon detection of AF episodes ≥6 minutes (the intervention group), or usual care. A total of 5,759 participants were included in the present analysis, where PWD, PWVI, and IAB were determined through a computerized analysis of 12-lead electrocardiogram and further employed to calculate baseline MVP score (0 to 6) for each participant. In total, 305 (5.3%) had stroke or systemic embolism during follow-up, with a higher risk in the group with MVP score 5 to 6 than those having score 0 to 2 (hazard ratio (HR) 1.54 [95% confidence interval (CI) 1.01 to 2.35]). This risk increase was mainly upheld by participants with IAB (HR 1.62 [95% CI 1.11 to 2.36] for IAB vs no IAB) and with longer PWD (HR 1.37 [95% CI 1.07 to 1.75] for >110 vs ≤110 ms). Compared with usual care, implantable loop recorder screening did not significantly reduce the risk of stroke or systemic embolism in any MVP risk categories (HR 0.80 [95% CI 0.60 to 1.08] for MVP score 0 to 2, 0.54 [95% CI 0.16 to 1.85] for MVP score 3 to 4, and 0.89 [95% CI 0.35 to 2.25] for MVP score 5 to 6; pinteraction = 0.78). In conclusion, a higher MVP score was associated with an increased stroke risk, but it did not demonstrate an association with effects of AF screening on stroke prevention. These findings should be considered hypothesis-generating and warrant further study.

Treatment-induced increase in total body potassium in patients at high risk of ventricular arrhythmias; a randomized POTCAST substudy.

OBJECTIVE: Hypokalemia is associated with increased risk of arrhythmias and it is recommended to monitor plasma potassium (p-K) regularly in at-risk patients with cardiovascular diseases. It is poorly understood if administration of potassium supplements and mineralocorticoid receptor antagonists (MRA) aimed at increasing p-K also increases intracellular potassium. METHODS: Adults aged≥18 years with an implantable cardioverter defibrillator (ICD) were randomized (1:1) to a control group or to an intervention that included guidance on potassium rich diets, potassium supplements, and MRA to increase p-K to target levels of 4.5-5.0 mmol/l for six months. Total-body-potassium (TBK) was measured by a Whole-Body-Counter along with p-K at baseline, after six weeks, and after six months. RESULTS: Fourteen patients (mean age: 59 years (standard deviation 14), 79% men) were included. Mean p-K was 3.8 mmol/l (0.2), and mean TBK was 1.50 g/kg (0.20) at baseline. After six-weeks, p-K had increased by 0.47 mmol/l (95%CI:0.14;0.81), p = 0.008 in the intervention group compared to controls, whereas no significant difference was found in TBK (44 mg/kg (-20;108), p = 0.17). After six-months, no significant difference was found in p-K as compared to baseline (0.16 mmol/l (-0.18;0.51), p = 0.36), but a significant increase in TBK of 82 mg/kg (16;148), p = 0.017 was found in the intervention group compared to controls. CONCLUSIONS: Increased potassium intake and MRAs increased TBK gradually and a significant increase was seen after six months. The differentially regulated p-K and TBK challenges current knowledge on potassium homeostasis and the time required before the full potential of p-K increasing treatment can be anticipated. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT03833089).

Electrocardiographic markers of subclinical atrial fibrillation detected by implantable loop recorder: insights from the LOOP Study.

AIMS: Insights into subclinical atrial fibrillation (AF) development are warranted to inform the strategies of screening and subsequent clinical management upon AF detection. Hence, this study sought to characterize the onset and progression of subclinical AF with respect to 12-lead electrocardiogram (ECG) parameters. METHODS AND RESULTS: We included AF-naïve individuals aged 70-90 years with additional stroke risk factors who underwent implantable loop recorder (ILR) monitoring in the LOOP Study. Using data from daily ILR recordings and the computerized analysis of baseline ECG, we studied empirically selected ECG parameters for AF detection (≥6 min), cumulative AF burden, long-lasting AF (≥24 h), and AF progression. Of 1370 individuals included, 419 (30.6%) developed AF during follow-up, with a mean cumulative AF burden of 1.5% [95% CI: 1.2-1.8]. Several P-wave-related and ventricular ECG parameters were associated with new-onset AF and with cumulative AF burden in AF patients. P-wave duration (PWD), P-wave terminal force in Lead V1, and interatrial block (IAB) further demonstrated significant associations with long-lasting AF. Among AF patients, we observed an overall reduction in cumulative AF burden over time (IRR 0.70 [95% CI: 0.51-0.96]), whereas IAB was related to an increased risk of progression to AF ≥24 h (HR 1.86 [95% CI: 1.02-3.39]). Further spline analysis also revealed longer PWD to be associated with this progression in AF duration. CONCLUSION: We identified several ECG parameters associated with new-onset subclinical AF detected by ILR. Especially PWD and IAB were robustly related to the onset and the burden of AF as well as progression over time.

Effects of Atrial Fibrillation Screening According to N-Terminal Pro-B-Type Natriuretic Peptide: A Secondary Analysis of the Randomized LOOP Study.

BACKGROUND: Research suggests NT-proBNP (N-terminal pro-B-type natriuretic peptide) to be a strong predictor of incident atrial fibrillation (AF) and stroke. However, its utility in AF screening remains unknown. The aim of this study was to investigate NT-proBNP as a potential marker for screening efficacy with respect to AF yield and stroke prevention. METHODS: In the LOOP Study (Atrial Fibrillation Detected by Continuous ECG Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-Risk Individuals), 6004 AF-naïve individuals at least 70 years old and with additional stroke risk factors were randomized 1:3 to either screening with an implantable loop recorder (ILR) and initiation of anticoagulation upon detection of AF episodes lasting ≥6 minutes or usual care (control). This post hoc analysis included study participants with available NT-proBNP measurement at baseline. RESULTS: A total of 5819 participants (96.9% of the trial population) were included. The mean age was 74.7 years (SD, 4.1 years) and 47.5% were female. The median NT-proBNP level was 15 pmol/L (interquartile range, 9-28 pmol/L) corresponding to 125 pg/mL (interquartile range, 76-233 pg/mL). NT-proBNP above median was associated with an increased risk of AF diagnosis both in the ILR group (hazard ratio, 1.84 [95% CI, 1.51-2.25]) and the control group (hazard ratio, 2.79 [95% CI, 2.30-3.40]). Participants with NT-proBNP above the median were also at higher risk of clinical events compared with those having lower levels (hazard ratio, 1.21 [95% CI, 0.96-1.54] for stroke or systemic embolism [SE], 1.60 [95% CI, 1.32-1.95] for stroke/SE/cardiovascular death, and 1.91 [95% CI, 1.61-2.26] for all-cause death). Compared with usual care, ILR screening was associated with significant reductions in stroke/SE and stroke/SE/cardiovascular death among participants with NT-proBNP above median (hazard ratio, 0.60 [95% CI, 0.40-0.90] and 0.70 [95% CI, 0.53-0.94], respectively) but not among those with lower levels (Pinteraction=0.029 for stroke/SE and 0.045 for stroke/SE/cardiovascular death). No risk reduction in all-cause death was observed in either NT-proBNP subgroup for ILR versus control (Pinteraction=0.68). Analyzing NT-proBNP as a continuous variable yielded similar findings. CONCLUSIONS: In an older population with additional stroke risk factors, ILR screening for AF was associated with a significant reduction in stroke risk among individuals with higher NT-proBNP levels but not among those with lower levels. These findings should be considered hypothesis generating and warrant further study before clinical implementation. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT02036450.

Prevalence and Prognostic Significance of Bradyarrhythmias in Patients Screened for Atrial Fibrillation vs Usual Care: Post Hoc Analysis of the LOOP Randomized Clinical Trial.

Importance: There is increasing interest in heart rhythm monitoring and technologies to detect subclinical atrial fibrillation (AF), which may lead to incidental diagnosis of bradyarrhythmias. Objective: To assess bradyarrhythmia prevalence and prognostic significance in persons screened for AF using implantable loop recorder (ILR) compared with unscreened persons. Design, Setting, and Participants: This was a post hoc analysis of the Implantable Loop Recorder Detection of Atrial Fibrillation to Prevent Stroke (LOOP) randomized clinical trial, which took place in 4 sites in Denmark. Participants were 70 years or older without known AF but diagnosed with at least 1 of the following: hypertension, diabetes, heart failure, or prior stroke. Participants were recruited by letter invitation between January 31, 2014, and May 17, 2016. The median (IQR) follow-up period was 65 (59-70) months. Analysis took place between February and June 2022. Interventions: ILR screening for AF with treatment of any bradyarrhythmia left to the discretion of the treating physician (ILR group) vs usual care (control group). Main Outcomes and Measures: Adjudicated bradyarrhythmia episodes, pacemaker implantation, syncope, and sudden cardiovascular death. Results: A total of 6004 participants were randomized (mean [SD] age, 75 [4.1] years; 2837 [47.3%] female; 5444 [90.7%] with hypertension; 1224 [20.4%] with prior syncope), 4503 to control and 1501 to ILR. Bradyarrhythmia was diagnosed in 172 participants (3.8%) in the control group vs 312 participants (20.8%) in the ILR group (hazard ratio [HR], 6.21 [95% CI, 5.15-7.48]; P < .001), and these were asymptomatic in 41 participants (23.8%) vs 249 participants (79.8%), respectively. The most common bradyarrhythmia was sinus node dysfunction followed by high-grade atrioventricular block. Risk factors for bradyarrhythmia included higher age, male sex, and prior syncope. A pacemaker was implanted in 132 participants (2.9%) vs 67 (4.5%) (HR, 1.53 [95% CI, 1.14-2.06]; P < .001), syncope occurred in 120 (2.7%) vs 33 (2.2%) (HR, 0.83 [95% CI, 0.56-1.22]; P = .34), and sudden cardiovascular death occurred in 49 (1.1%) vs 18 (1.2%) (HR, 1.11 [95% CI, 0.64-1.90]; P = .71) in the control and ILR groups, respectively. Bradyarrhythmias were associated with subsequent syncope, cardiovascular death, and all-cause death, with no interaction between bradyarrhythmia and randomization group. Conclusions and Relevance: More than 1 in 5 persons older than 70 years with cardiovascular risk factors can be diagnosed with bradyarrhythmias when long-term continous monitoring for AF is applied. In this study, ILR screening led to a 6-fold increase in bradyarrhythmia diagnoses and a significant increase in pacemaker implantations compared with usual care but no change in the risk of syncope or sudden death.

Screening for atrial fibrillation to prevent stroke in elderly individuals with or without preexisting cardiovascular disease: A post hoc analysis of the randomized LOOP Study.

BACKGROUND: An evidence-based approach for risk stratification of subclinical atrial fibrillation (AF) and hereby AF screening is lacking. This study aimed to investigate whether established cardiovascular diseases (CVD) could help to identify the population more likely to benefit from AF screening. METHODS: The LOOP Study randomized AF-naïve individuals aged ≥70 years and with additional stroke risk factors to either screening with implantable loop recorder (ILR) and subsequent anticoagulation upon detection of new-onset AF episodes ≥6 min, or usual care. In this sub-study, all participants were divided into two risk groups according to the presence/absence of CVD (defined as ischemic heart disease, heart failure, previous stroke, valvular heart disease, or peripheral artery disease). RESULTS: A total of 1997 (33.3%) had CVD at baseline and experienced higher incidences of stroke or systemic arterial embolism (SAE), ischemic stroke, stroke/SAE/cardiovascular death, and all-cause death (adjusted HR 1.34 [1.06-1.69], 1.31 [1.02-1.69], 1.49 [1.23-1.79], and 1.59 [1.36-1.85], respectively) than those without. For ILR screening versus usual care, there was no decrease in stroke/SAE, ischemic stroke, or stroke/SAE/cardiovascular death among participants with CVD (adjusted p-values >0.05), whereas significant reductions in these outcomes were obtained by screening among those without CVD (adjusted HR 0.64 [0.44-0.93], 0.54 [0.35-0.82], 0.64 [0.46-0.87], respectively); adjusted p-values for interaction ≤0.05. CONCLUSIONS: In an elderly, at-risk population, ILR screening did not prevent stroke significantly in individuals with CVD, whereas screening was associated with approximately 40% stroke risk reduction among those without CVD. However, these findings should be considered as hypothesis-generating and warrant further study.

Severity and Etiology of Incident Stroke in Patients Screened for Atrial Fibrillation vs Usual Care and the Impact of Prior Stroke: A Post Hoc Analysis of the LOOP Randomized Clinical Trial.

Importance: Atrial fibrillation (AF) screening trials have failed to demonstrate a significant reduction in stroke risk. The impact on stroke severity and the importance of prior strokes are unknown. Objective: To assess stroke characteristics in patients undergoing implantable loop recorder (ILR) screening for AF vs usual care and assess the importance of prior stroke. Design, Setting, and Participants: This was a post hoc analysis of the Atrial Fibrillation Detected by Continuous Electrocardiogram Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-Risk Individuals (LOOP) randomized clinical trial. Persons 70 years or older without known AF but diagnosed with 1 or more of the following, hypertension, diabetes, heart failure, or prior stroke, were screened for inclusion. Four sites in Denmark recruited participants by letter between January 31, 2014, and May 17, 2016. The median (IQR) follow-up period was 65 (59-70) months. Data were analyzed from April 1 to May 31, 2022. Interventions: ILR screening for AF and anticoagulation initiation if AF duration of 6 minutes or longer was detected (ILR group) vs usual care (control group). Main Outcomes and Measures: Adjudicated stroke, classified according to the modified Rankin Scale (mRS) using a score of 3 or more as a cutoff for severe (disabling or lethal) stroke, and according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification for ischemic strokes. Results: A total of 6205 individuals were screened for inclusion, and 6004 were randomized and included in the analysis; 4503 participants (75%; mean [SD] age, 74.7 [4.1] years; 2375 male [52.7%]) were assigned to the control group and 1501 participants (25%; mean [SD] age, 74.7 [4.1] years; 792 male [52.8%]) were assigned to the ILR group. A total of 794 of 4503 participants (17.6%) in the control group had a history of prior stroke compared with 262 of 1501 participants (17.5%) in the ILR group. During follow-up, AF was diagnosed in 1027 participants (control group, 550 [12%] vs ILR group, 477 [32%]), and anticoagulation was initiated in 89% of these (910). A total of 315 participants (5.2%) had a stroke (control group, 249 [5.5%] vs ILR group, 66 [4.4%]), and the median (IQR) mRS score was 2 (1-3) with no difference across the groups. A total of 272 participants (4.5%) had ischemic stroke (control group, 217 [4.8%] vs ILR group, 55 [3.7%]), and 123 (2.0%) had severe stroke (control group, 100 [2.2%] vs ILR group, 23 [1.5%]), and the hazard ratios comparing the control and ILR groups were 0.76 (95% CI, 0.57-1.03; P = .07) and 0.69 (95% CI, 0.44-1.09; P = .11), respectively. For participants without prior stroke, the hazard ratios were 0.68 (95% CI, 0.48-0.97; P = .04) and 0.54 (95% CI, 0.30-0.97; P = .04), respectively. Conclusions and Relevance: This post hoc analysis of the LOOP randomized clinical trial found that ILR screening for AF did not result in a significant decrease in ischemic or severe strokes compared with usual care. Exploratory subgroup analyses indicated a possible reduction of these outcomes among participants without prior stroke. Trial Registration: ClinicalTrials.gov Identifier: NCT02036450.

Targeted potassium levels to decrease arrhythmia burden in high risk patients with cardiovascular diseases (POTCAST): Study protocol for a randomized controlled trial.

BACKGROUND: Low plasma potassium (p-K) is associated with increased risk of malignant arrhythmia and observational studies indicate protective effects of p-K in the upper reference level. However, randomized clinical studies are needed to document whether actively increasing p-K to high-normal levels is possible and safe and improves cardiovascular outcomes. OBJECTIVE: To investigate if increased p-K reduces the risk of malignant arrhythmia and all-cause death in high-risk patients with a cardiovascular disease treated with an implantable cardioverter defibrillator (ICD) for primary or secondary preventive causes. Secondly, to investigate whether high-normal p-K levels can be safely reached and maintained using already available medications and potassium-rich dietary guidance. METHODS: This is a prospective, randomized, and open-labelled study enrolling patient at high-risk of malignant arrhythmias. According to sample size calculations, 1,000 patients will be randomized 1:1 to either an investigational regiment that aims to increase and maintain p-K at high-normal levels (4.5-5.0 mmol/L) or to usual standard of care and followed for an expected four years. The trial will run until a total of 291 events have occurred providing an α = 0.05 and 1-ß = 0.80. The composite primary endpoint includes ventricular tachycardia >125 bpm lasting >30 seconds, any appropriate ICD-therapy, and all-cause mortality. At present, 739 patients have been randomized. CONCLUSIONS: We present the rationale for the design of the POTCAST trial. The inclusion was initiated 2019 and is expected to be finished 2022. The study will show if easily available treatments to increase p-K may be a new treatment modality to protect against malignant arrythmias.

Systolic Blood Pressure and Effects of Screening for Atrial Fibrillation With Long-Term Continuous Monitoring (a LOOP Substudy).

BACKGROUND: Hypertension is a well-known risk factor for atrial fibrillation (AF) and stoke, but data on the interaction between systolic blood pressure (SBP) and effects of AF screening are lacking. METHODS: The LOOP Study randomized AF-naïve individuals aged 70 to 90 years with additional stroke risk factors to either screening with implantable loop recorder (ILR) and anticoagulation initiation upon detection of AF episodes ≥6 minutes, or usual care. In total, 5997 participants with available baseline SBP measurements were included in this substudy. Outcomes were analyzed according to the time-to-first-event principle using cause-specific Cox models. RESULTS: The hazard ratio of stroke or systemic arterial embolism for ILR versus control decreased with increasing SBP. ILR screening yielded a 44% risk reduction of stroke or systemic arterial embolism among participants with SBP ≥150 mm Hg (adjusted hazard ratio, 0.56 [0.37-0.83]). Within the ILR group, SBP≥150 mm Hg was associated with a higher incidence of AF episodes ≥24 hours than lower SBP (adjusted hazard ratio, 1.70 [1.08-2.69]) but not with the overall occurrence of AF (adjusted P>0.05). CONCLUSIONS: The impact of AF screening on thromboembolic events increased with increasing blood pressure. SBP≥150 mm Hg was associated with a >1.5-fold increased risk of AF episodes ≥24 hours, along with an almost 50% risk reduction of stroke or systemic arterial embolism by ILR screening compared to lower blood pressure. These findings should be considered hypothesis-generating and warrant further study. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique Identifier: NCT02036450.

Potential role of conventional and speckle-tracking echocardiography in the screening of structural and functional cardiac abnormalities in elderly individuals: Baseline echocardiographic findings from the LOOP study.

BACKGROUND: Elderly individuals occupy an increasing part of the general population. Conventional and speckle-tracking transthoracic echocardiography may help guide risk stratification in these individuals. The purpose of this study was to evaluate the potential utility of conventional and speckle-tracking echocardiography in the screening of cardiac abnormalities in the elderly population. METHODS: Two cohorts of elderly individuals (sample size: 1441 and 944) were analyzed, who were part of a randomized controlled clinical trial (LOOP study) and of an observational study (Copenhagen City Heart Study), recruiting participants from the general population >70 years of age with cardiovascular risk factors (arterial hypertension, diabetes mellitus, heart failure, or prior stroke) and sinus rhythm. Participants underwent a comprehensive transthoracic echocardiographic examination, including myocardial speckle tracking. Cardiac abnormalities were defined according to the ASE/EACVI guidelines. RESULTS: Structural cardiac abnormalities such as left ventricular (LV) remodeling, mitral annular calcification (MAC), and aortic valve sclerosis (with or without stenosis) were highly prevalent in the LOOP study (40%, 39%, and 27%, respectively). Moreover, a high prevalence of functional cardiac alterations such as LV diastolic dysfunction (LVDD), abnormal LV longitudinal systolic strain (GLS), and abnormal left atrial (LA) reservoir strain was present in the LOOP study (27%, 18%, and 9%, respectively). Likewise, the rate of LVDD, abnormal GLS, and abnormal LA reservoir strain was comparable in the validation sample from the Copenhagen City Heart Study. In line with these findings, subjects with LV remodeling, MAC, and aortic valve changes had a higher prevalence of LVDD, abnormal GLS, and abnormal LA reservoir strain than those without structural cardiac alterations. CONCLUSION: The findings of this study highlight the potential clinical utility of conventional and speckle-tracking echocardiography in the screening of structural and functional cardiac abnormalities in the elderly population. Further studies are warranted to determine the prognostic relevance of these findings.

Accuracy, analysis time, and reproducibility of dedicated 4D echocardiographic left atrial volume quantification software.

Four-dimensional (4D) echocardiography may provide more accurate estimations of left atrial (LA) volumes than 2-dimensional (2D) measures. We sought to compare the concordance of a novel 4D LA quantification software versus 2D echocardiography against cardiac magnetic resonance (CMR). This was a multimodality imaging substudy of a randomized clinical trial (the LOOP study). Elderly participants with stroke risk factors were included. A subgroup of this study population underwent transthoracic echocardiography (n = 1441) and a subset underwent CMR within two weeks (n = 73). The mean age of the echocardiographic study population was 74 years and 54% were men. The maximal LA volume (LAVmax) was 47 mL by 2D, 52 mL by 4D, and 104 mL by CMR. While 2D echocardiography showed a moderate correlation with 4D (R2 = 0.51) it yielded significantly lower values for LAVmax with a mean difference of 4.5 ± 11.9 mL, p < 0.001. 4D echocardiography correlated strongly with CMR measurements (R2 = 0.70), whereas 2D echocardiography showed a moderate correlation (R2 = 0.53). However, both modalities systematically underestimated LAVmax largely compared to CMR (2D vs. CMR: - 54.9 ± 21.3 mL; 4D vs. CMR: - 49.7 ± 18.6 mL). Similar observations were made for minimal LA volume and LA volume before atrial contraction. Analyses time by 4D was shorter than for 2D (90 ± 11 vs. 118 ± 16 s, p < 0.001). Intra- and interobserver variability was lower for 4D than 2D. Four-dimensional echocardiography is faster, more reproducible, and correlates more closely to CMR than 2D echocardiography. Both 4D and 2D echocardiography systematically underestimates LA volumes compared to CMR, emphasizing that values of LA volumes are not interchangeable between echocardiography and CMR.