Noninvasive electrocardiographic risk factors for sudden cardiac death in dilated ca rdiomyopathy: is ambulatory electrocardiography still relevant?

Risk stratification for sudden cardiac death in dilated cardiomyopathy is a field of constant debate, and the currently proposed criteria have been widely questioned due to their low positive and negative predictive value. In this study, we conducted a systematic review of the literature utilizing the PubMed and Cochrane library platforms, in order to gain insight about dilated cardiomyopathy and its arrhythmic risk stratification utilizing noninvasive risk markers derived mainly from 24 h electrocardiographic monitoring. The obtained articles were reviewed in order to register the various electrocardiographic noninvasive risk factors used, their prevalence, and their prognostic significance in dilated cardiomyopathy. Premature ventricular complexes, nonsustained ventricular tachycardia, late potentials on Signal averaged electrocardiography, T wave alternans, heart rate variability and deceleration capacity of the heart rate, all have both some positive and negative predictive value to identify patients in higher likelihood for ventricular arrhythmias and sudden cardiac death. Corrected QT, QT dispersion, and turbulence slope-turbulence onset of heart rate have yet to establish a predictive correlation in the literature. Although ambulatory electrocardiographic monitoring is frequently used in clinical practice in DCM patients, no single risk marker can be used for the selection of patients at high-risk for malignant ventricular arrhythmic events and sudden cardiac death who could benefit from the implantation of a defibrillator. More studies are needed in order to establish a risk score or a combination of risk factors with the purpose of selecting high-risk patients for ICD implantation in the context of primary prevention.

Clinical Outcomes of Left Bundle Branch Area Pacing Compared with Biventricular Pacing in Patients with Heart Failure Requiring Cardiac Resynchronization Therapy: Systematic Review and Meta-Analysis.

Background: Biventricular pacing (BVP) is recommended for patients with heart failure (HF) who require cardiac resynchronization therapy (CRT). Left bundle branch area pacing (LBBAP) is a novel pacing strategy that appears to ensure better electrical and mechanical synchrony in these patients. Our aim was to systematically review and meta-analyze the existing evidence regarding the clinical outcomes of LBBAP-CRT compared with BVP-CRT. Methods: Medline, Embase, Cochrane Central Register of Controlled Trials and Web of Science databases were searched for studies comparing LBBAP-CRT with BVP-CRT. Outcomes were all-cause mortality, heart failure hospitalizations (HFH) and New York Heart Association (NYHA) class improvement. We included randomized controlled trials (RCTs) and observational studies with participants that had left ventricular ejection fraction (LVEF) ≤ 40% and (i) symptomatic HF or (ii) expected ventricular pacing > 40%. Random and fixed effects models pairwise meta-analysis was conducted. Cochrane Risk of Bias 2 assessment tool (ROB 2.0) and the Newcastle-Ottawa scale (NOS) were used to assess the quality of the studies. Results: Eleven studies (10 observational studies and 1 RCT) with 3141 patients were included in the analysis. Compared with BVP-CRT, LBBAP-CRT was associated with lower risk of all-cause mortality (risk ratio (RR): 0.71, 95% CI: 0.57 to 0.87; p = 0.001), lower risk of HFH (RR: 0.59, 95% CI: 0.50 to 0.71; p < 0.00001) and more improvement in NYHA class (weighed mean difference (WMD): -0.36, 95% CI: -0.59 to -0.13; p < 0.00001) compared with patients who received BVP-CRT. Conclusions: Compared with BVP-CRT, receipt of LBBAP-CRT in patients with HF is associated with a lower risk of mortality, and HFH and greater improvement in NHYA class.

Speckle tracking echocardiography and ß-thalassemia major. A systematic review.

Heart disease is among the primary causes of morbidity and mortality in ß-thalassemia major (ß-TM). Conventional echocardiography has failed to identify myocardial dysfunction at an early stage among these patients, thus speckle tracking echocardiography (STE) has been lately used. The objectives of this review were to 1) identify all published studies having evaluated myocardial strain among ß-TM patients, 2) gather their results, 3) compare their findings and 4) propose recommendations based on these data. Literature search was conducted in PubMed, SCOPUS and Cohrane Library. Data regarding left ventricular global longitudinal (LV-GLS), circumferential (LV-GCS) and radial strain (LV-GRS), right ventricular longitudinal strain (RV-GLS), left and right atrial strain were extracted. Thirty-five studies (34 original articles and 1 meta-analysis) have met the inclusion criteria. LV-GLS has been reported being worse in patients compared to controls in 13 of 21 studies, LV-GCS in 7 of 11 studies, LV-GRS in 6 of 7 studies, RV-GLS in 2 of 3 studies and left atrial strain in all case-control studies. Myocardial iron overload (MIO) patient subgroups had worse LV-GLS in 6 of 15 studies, LV-GCS in 2 of 7 studies and LV-GRS in none of 7 studies. A small number of studies suggest left atrial strain correlation with electrical atrial ectopy and atrial fibrillation. It is suggested that STE should be applied supplementary to conventional echocardiography for early identification of myocardial dysfunction among ß-TM patients. Potential myocardial strain utilities could be screening for myocardial iron overload, left ventricular diastolic dysfunction and atrial fibrillation.

Risk assessment of post-myocardial infarction patients with preserved ejection fraction using 45-min short resting Holter electrocardiographic recordings.

BACKGROUND: Risk stratification for sudden cardiac death in post-myocardial infarction (post-MI) patients remains a challenging task. Several electrocardiographic noninvasive risk factors (NIRFs) have been associated with adverse outcomes and were used to refine risk assessment. This study aimed to evaluate the performance of NIRFs extracted from 45-min short resting Holter ECG recordings (SHR), in predicting ventricular tachycardia inducibility with programmed ventricular stimulation (PVS) in post-MI patients with preserved left ventricular ejection fraction (LVEF). METHODS: We studied 99 post-MI ischemia-free patients (mean age: 60.5 ± 9.5 years, 86.9% men) with LVEF ≥40%, at least 40 days after revascularization. All the patients underwent PVS and a high-resolution SHR. The following parameters were evaluated: mean heart rate, ventricular arrhythmias (premature ventricular complexes, couplets, tachycardias), QTc duration, heart rate variability (HRV), deceleration capacity, heart rate turbulence, late potentials, and T-wave alternans. RESULTS: PVS was positive in 24 patients (24.2%). HRV, assessed by the standard deviation of normal-to-normal R-R intervals (SDNN), was significantly decreased in the positive PVS group (42 ms vs. 51 ms, p = .039). SDNN values <50 ms were also associated with PVS inducibility (OR 3.081, p = .032 in univariate analysis, and 4.588, p = .013 in multivariate analysis). No significant differences were identified for the other NIRFs. The presence of diabetes, history of ST-elevation MI (STEMI) and LVEF <50% were also important predictors of positive PVS. CONCLUSIONS: HRV assessed from SHR, combined with other noninvasive clinical and echocardiographic variables (diabetes, STEMI history, LVEF), can provide an initial, practical, and rapid screening tool for arrhythmic risk assessment in post-MI patients with preserved LVEF.

Anticoagulation Status and Left Atrial Appendage Occlusion Indications in Hospitalized Cardiology Patients with Atrial Fibrillation: A Hellenic Cardiorenal Morbidity Snapshot (HECMOS) Sub-Study.

Background and Objectives: The proper use of oral anticoagulants is crucial in the management of non-valvular atrial fibrillation (AF) patients. Left atrial appendage closure (LAAC) may be considered for stroke prevention in patients with AF and contraindications for long-term anticoagulant treatment. We aimed to assess anticoagulation status and LAAC indications in patients with AF from the HECMOS (Hellenic Cardiorenal Morbidity Snapshot) survey. Materials and Methods: The HECMOS was a nationwide snapshot survey of cardiorenal morbidity in hospitalized cardiology patients. HECMOS used an electronic platform to collect demographic and clinically relevant information from all patients hospitalized on 3 March 2022 in 55 different cardiology departments. In this substudy, we included patients with known AF without mechanical prosthetic valves or moderate-to-severe mitral valve stenosis. Patients with prior stroke, previous major bleeding, poor adherence to anticoagulants, and end-stage renal disease were considered candidates for LAAC. Results: Two hundred fifty-six patients (mean age 76.6 ± 11.7, 148 males) were included in our analysis. Most of them (n = 159; 62%) suffered from persistent AF. The mean CHA2DS2-VASc score was 4.28 ± 1.7, while the mean HAS-BLED score was 1.47 ± 0.9. Three out of three patients with a a CHA2DS2-VASc score of 0 or 1 (female) were inappropriately anticoagulated. Sixteen out of eighteen patients with a CHA2DS2-VASc score 1 or 2 (if female) received anticoagulants. Thirty-one out of two hundred thirty-five patients with a CHA2DS2-VASc score > 1 or 2 (if female) were inappropriately not anticoagulated. Relative indications for LAAC were present in 68 patients with NVAF (63 had only one risk factor and 5 had two concurrent risk factors). In detail, 36 had a prior stroke, 17 patients had a history of major bleeding, 15 patients reported poor or no adherence to the anticoagulant therapy and 5 had an eGFR value < 15 mL/min/1.73 m2 for a total of 73 risk factors. Moreover, 33 had a HAS-BLED score ≥ 3. No LAAC treatment was recorded. Conclusions: Anticoagulation status was nearly optimal in a high-thromboembolic-risk population of cardiology patients who were mainly treated using NOACs. One out of four AF patients should be screened for LAAC.

Effectiveness and safety of a time to isolation strategy of cryoballoon ablation of atrial fibrillation: A systematic review and meta-analysis.

AIM: We conducted a systematic review and meta-analysis of randomized and observational studies with a control group to evaluate the effectiveness and safety of a time to isolation (TTI)-based strategy of cryoballoon ablation (CBA) in the treatment of atrial fibrillation (AF). METHODS: Three electronic databases (MEDLINE, Cochrane Central Register of Controlled Trials, and Embase) without language restrictions were searched. The intervention assessed was a TTI-based strategy of CBA in the treatment of AF. TTI was defined as the time from the start of freezing to the last recorded pulmonary veins' potential. The comparison of interest was intended conventional protocol of CBA. The primary endpoint was freedom from atrial arrhythmia. RESULTS: Nine studies were deemed eligible (N = 2289 patients). Eight studies reported freedom from atrial arrhythmia and pooled results showed a marginally similar success rate between the two protocols (odds ratio [OR]: 1.24; 95% confidence interval [CI]: 0.98-1.56). A prespecified subgroup analysis verified that a high dose TTI strategy (with >120 s duration of cryotherapy post-TTI) compared to the conventional protocol could significantly increase the patients without atrial arrhythmia during follow-up (OR: 1.39; 95% CI: 1.05-1.83). TTI strategy could also significantly decrease total procedure time (SMD: -26.24 min; 95% CI: -36.90 to -15.57) and phrenic nerve palsy incidence (OR: 0.49; 95% CI: 0.29-0.84). CONCLUSION: Moderate confidence evidence suggests that an individualized CBA dosing strategy based on TTI and extended (>2 min post-TTI) duration of CBA is accompanied by fewer recurrences post-AF ablation.

The Role of Genetics in Risk Stratification Strategy of Dilated Cardiomyopathy.

Dilated cardiomyopathy (DCM) is a heart disorder of diverse etiologies that affects millions of people worldwide, associated with increased mortality rate and high risk of sudden cardiac death. Patients with DCM are characterized by a wide range of clinical and pre-clinical phenotypes which are related with different outcomes. Dominant studies have failed to demonstrate the value of the left ventricular ejection fraction as the only indicator for patients' assessment and arrhythmic events prediction, thus making sudden cardiac death (SCD) risk stratification strategy improvement, more crucial than ever. The multifactorial two-step approach, examining non-invasive and invasive risk factors, represents an alternative process that enhances the accurate diagnosis and the individualization of patients' management. The role of genetic testing, regarding diagnosis and decision making, is of great importance, as pathogenic variants have been detected in several patients either they had a disease relative family history or not. At the same time there are specific genes mutations that have been associated with the prognosis of the disease. The aim of this review is to summarize the latest data regarding the genetic substrate of DCM and the value of genetic testing in patients' assessment and arrhythmic risk evaluation. Undoubtedly, the appropriate application of genetic testing and the thoughtful analysis of the results will contribute to the identification of patients who will receive major benefit from an implantable defibrillator as preventive treatment of SCD.

Left atrial deformation indices in ß-thalassemia major patients.

The presence of atrial cardiomyopathy in ß-thalassemia major (ß-TM) patients complicates their clinical condition. The diagnosis is challenging even with cardiac magnetic resonance (CMR) imaging. Novel echocardiographic techniques are applied to increase the diagnostic yield. Fifty-six ß-TM patients and thirty age and sex-matched controls were included in the present cross-sectional study. Heart rate, PR duration, and P axis were measured by electrocardiography, left ventricular ejection fraction (LVEF) and end-diastolic diameter (LVEDD), ratio between early mitral inflow velocity and mitral annular early diastolic velocity (E/e'), left atrial volume index (LAVI), left atrial strain at reservoir (LASr), conduit (LAScd) and contraction (LASct) phases respectively, left ventricular global longitudinal strain (GLS) by echocardiography, and T2* calculation in patient group by CMR. PR duration, LVEF, LAVI, E/e', GLS, and left atrial deformation parameters differed between patients and controls (p <0.05). In patient group, left atrial strain was correlated with PR duration, LAVI, E/e', GLS, and T2* (p <0.05). T2* was correlated only with left atrial deformation indices (p <0.05). Patients with a history of atrial fibrillation were older, had lower heart rate, prolonged PR, increased E/e' and LAVI, and impaired left atrial strain (p <0.05). LASct differed relative to the presence of atrial fibrillation and myocardial iron overload. Atrial strain could be of clinical use in the early detection of atrial cardiomyopathy. An impaired LASct could identify ß-TM patients with undetected episodes of atrial fibrillation. Finally, left atrial strain may be helpful in myocardial iron load estimation.

Atrial High-Rate Episodes in Patients with Devices Without a History of Atrial Fibrillation: a Systematic Review and Meta-analysis.

PURPOSE: Atrial high-rate episodes (AHREs) recorded with cardiac implantable electronic devices (CIEDs) have been associated with the development of clinical atrial fibrillation (AF) and increase in stroke and death risk. We sought to perform a systematic review with a meta-analysis to evaluate the prevalence of AHREs detected by CIEDs, their association with stroke risk, development of clinical AF, and mortality among patients without a documented history of AF. METHODS: We searched several databases, ClinicalTrials.gov, references of reviews, and meeting abstract books without any language restrictions up to 9 September 2020. We studied patients with CIEDs in whom AHREs were detected. Exclusion criterion was AF history. Our primary outcome was the risk of ischemic stroke in patients with AHREs. RESULTS: We deemed eligible eight studies for the meta-analysis enrolling a total of 4322 patients with CIED and without a documented AF history. The overall AHRE incidence ratio was estimated to be 17.56 (95% CI, 8.61 to 35.79) cases per 100 person-years. Evidence of moderate certainty suggests that patients with documented AHREs were 4.45 times (95% CI 2.87-6.91) more likely to develop clinical AF. Evidence of low confidence suggests that AHREs were associated with a 1.90-fold increased stroke risk (95% CI 1.19-3.05). AHREs were not associated with a statistically significant increased mortality risk. CONCLUSION: The present systematic review and meta-analysis demonstrated that among patients without a documented history of AF, the detection of AHREs by CIEDs was associated with significant increased risk of clinical AF and stroke. REGISTRATION NUMBER (DOI): Available in https://doi.org/10.17605/OSF.IO/ZRF6M .

Reappraising the role of class Ic antiarrhythmics in atrial fibrillation.

PURPOSE: The objective of the present systematic review was to compare the effectiveness and safety of class Ic agents for cardioversion of paroxysmal atrial fibrillation (AF), in patients with and without structural heart disease (SHD). METHODS: We focused on RCTs enrolling at least 50 adult patients with electrocardiogram-documented paroxysmal AF that compared either two pharmacological class Ic cardioversion agents (flecainide, propafenone), regardless of study design (parallel or crossover). We searched MEDLINE and the Cochrane Central Register of Controlled Trials. Initial search was performed from inception to 15 July 2021 with no language restrictions. RESULTS: Intravenous flecainide is the most effective option for pharmacologic cardioversion of AF since only 2 patients need to be treated in order to cardiovert one more within 4 h. Most importantly, class Ic agents appear to be safe in the context of pharmacologic cardioversion of AF irrespective of the presence of SHD, pointing towards a possible reappraisal of the role in this setting. CONCLUSION: We suggest that class Ic agents (with flecainide appearing to be more effective) should be used for pharmacologic cardioversion in stable AF patients presenting in emergency department with unknown medical history, after excluding severe cardiac disease through a bedside examination. REGISTRATION NUMBER (DOI): Available in https://osf.io/apwt7/ , https://doi.org/10.17605/OSF.IO/APWT7.

Association of non-invasive electrocardiographic risk factors with left ventricular systolic function in post-myocardial infarction patients with mildly reduced or preserved ejection fraction: Insights from the PRESERVE-EF study.

BACKGROUND: Electrocardiographic non-invasive risk factors (NIRFs) have an important role in the arrhythmic risk stratification of post-myocardial infarction (post-MI) patients with preserved or mildly reduced left ventricular ejection fraction (LVEF). However, their specific relation to left ventricular systolic function remains unclear. We aimed to evaluate the association between NIRFs and LVEF in the patients included in the PRESERVE-EF trial. METHODS: We studied 575 post-MI ischemia-free patients with LVEF≥40% (mean age: 57.0 ± 10.4 years, 86.2% men). The following NIRFs were evaluated: premature ventricular complexes, non-sustained ventricular tachycardia (NSVT), late potentials (LPs), prolonged QTc, increased T-wave alternans, reduced heart rate variability, and abnormal deceleration capacity with abnormal turbulence. RESULTS: There was a statistically significant relationship between LPs (Chi-squared = 4.975; p < .05), nsVT (Chi-squared = 5.749, p < .05), PVCs (r= -.136; p < .01), and the LVEF. The multivariate linear regression analysis showed that LPs (p = .001) and NSVT (p < .001) were significant predictors of the LVEF. The results of the multivariate logistic regression analysis indicated that LPs (OR: 1.76; 95% CI: 1.02-3.05; p = .004) and NSVT (OR: 2.44; 95% CI: 1.18-5.04; p = .001) were independent predictors of the mildly reduced LVEF: 40%-49% versus the preserved LVEF: ≥50%. CONCLUSION: Late potentials and NSVT are independently related to reduced LVEF while they are independent predictors of mildly reduced LVEF versus the preserved LVEF. These findings may have important implications for the arrhythmic risk stratification of post-MI patients with mildly reduced or preserved LVEF.

Noninvasive risk factors for the prediction of inducibility on programmed ventricular stimulation in post-myocardial infarction patients with an ejection fraction ≥40% at risk for sudden cardiac arrest: Insights from the PRESERVE-EF study.

BACKGROUND: In the PRESERVE-EF study, a two-step sudden cardiac death (SCD) risk stratification approach to detect post-myocardial infarction (MI) patients with left ventricle ejection fraction (LVEF) ≥40% at risk for major arrhythmic events (MAEs) was used. Seven noninvasive risk factors (NIRFs) were extracted from a 24-h ambulatory electrocardiography (AECG) and a 45-min resting recording. Patients with at least one NIRF present were referred for invasive programmed ventricular stimulation (PVS) and inducible patients received an Implantable Cardioverter - Defibrillator (ICD). METHODS: In the present study, we evaluated the performance of the NIRFs, as they were described in the PRESERVE-EF study protocol, in predicting a positive PVS. In the PRESERVE-EF study, 152 out of 575 patients underwent PVS and 41 of them were inducible. For the present analysis, data from these 152 patients were analyzed. RESULTS: Among the NIRFs examined, the presence of signal averaged ECG-late potentials (SAECG-LPs) ≥ 2/3 and non-sustained ventricular tachycardia (NSVT) ≥1 eposode/24 h cutoff points were important predictors of a positive PVS study, demonstrating in the logistic regression analysis odds ratios 2.285 (p = .027) and 2.867 (p = .006), respectively. A simple risk score based on the above cutoff points in combination with LVEF < 50% presented high sensitivity but low specificity for a positive PVS. CONCLUSION: Cutoff points of NSVT ≥ 1 episode/24 h and SAECG-LPs ≥ 2/3 in combination with a LVEF < 50% were important predictors of inducibility. However, the final decision for an ICD implantation should be based on a positive PVS, which is irreplaceable in risk stratification.

QT interval extracted from 30-minute short resting Holter ECG recordings predicts mortality in heart failure.

BACKGROUND: Prolonged repolarization duration is a significant total mortality (TM) predictor in post-myocardial infarction patients. AIM: We examined the clinical significance of QT interval that was extracted from a Short Resting Holter ECG (SRH ECG - 30-min duration) as a TM predictor in heart failure (HF) patients. METHODS: One hundred forty-five HF patients (male = 84%, mean age = 64 ± 12 years, mean LVEF = 33 ± 10%) underwent an SRH ECG recording for 30 min. These high-resolution ECG signals were analyzed and the QT interval was calculated and corrected according to the Fridericia formula. After 42.1 months, 26 patients died. RESULTS: Univariate analysis for Deceased and Living groups: QTc:455 ± 33 ms vs 441 ± 32 ms (p = 0.04), LVEF:32 ± 10% vs 34 ± 9% (p < 0.5), Mean Heart Rate: 73 ± 11 bpm vs 69 ± 12 bpm (p = 0.2), SDNN/HRV: 45 ± 42 ms vs 41 ± 29 ms (p = 0.4), QRS: 123 ± 26 ms vs 119 ± 29 ms (p = 0.5). Multivariate Cox regression analysis with model adjusted for QTc, Mean Heart Rate, LVEF, QRS, revealed that QTc-Fridericia interval was an independent TM predictor (H.R.:1.017, 95% C.I.: 1.003-1.030, p = 0.01). The cut-off point of 490 ms (90th percentile) in the same model presented HR: 2.9 for TM (95%C.I.: 1.066-7.882, p = 0.03). Kaplan Meier curves depicted a clear difference in survival between the two patients' groups (QTc Group≥490 ms vs QTc Group <490 ms). The curve diverge was important (log-rank, p = 0.02). CONCLUSION: A fast risk stratification approach with SRH ECG recording is an efficient method for flash evaluation of mortality risk in HF patients.

Transvenous extraction of permanent pacemaker and defibrillator leads: Reduced procedural complexity and higher procedural success rates in patients with infective versus noninfective indications.

INTRODUCTION: Transvenous lead extraction (TLE) is critical in the long-term management of patients with cardiac implanted electronic devices (CIEDs). The aim of the study is to evaluate the outcomes of TLE and to investigate the impact of infection. METHODS AND RESULTS: Data of patients undergoing extraction of permanent pacemaker and defibrillator leads during October 2014-September 2019 were prospectively analyzed. Overall, 242 consecutive patients (aged 71.0 ± 14.0 years, 31.4% female), underwent an equal number of TLE operations for the removal of 516 leads. Infection was the commonest indication (n = 201, 83.1%). Mean implant-to-extraction duration was 7.6 ± 5.4 years. Complete procedural success was recorded in 96.1%, and clinical procedural success was achieved in 97.1% of attempted lead extractions. Major complications occurred in two (0.8%) and minor complications in seven (2.9%) patients. Leads were removed exclusively by using locking stylets in 65.7% of the cases. In the subgroup of noninfective patients, advanced extraction tools were more frequently required compared to patients with CIED infections, to extract leads (success only with locking stylet: 55.8% vs. 67.8%, p = .032). In addition, patients without infection demonstrated lower complete procedural success rates (90.7% vs. 97.2%, p = .004), higher major complication rates (2.4% vs. 0.5%, p = .31) and longer procedural times (136 ± 13 vs. 111 ± 15 min, p = .001). CONCLUSIONS: Our data demonstrate high procedural efficacy and safety and indicate that in patients with noninfective indications, the procedure is more demanding, thus supporting the hypothesis that leads infection dissolves and/or prohibits the formation of fibrotic adherences.

Pharmacologic Cardioversion in Patients with Paroxysmal Atrial Fibrillation: A Network Meta-Analysis.

PURPOSE: We sought to indirectly compare and rank antiarrhythmic agents focusing exclusively on adults with paroxysmal atrial fibrillation in order to identify the most effective for pharmacologic cardioversion over different time settings (4 h as primary, and 12, 24 h as secondary outcomes). METHODS: We searched several databases from inception to March 2020 without language restrictions, ClinicalTrials.gov, references of reviews, and meeting abstract material. We included randomized controlled trials of patients with AF lasting ≤7 days comparing either two or more intravenous (i.v.) or oral (p.o.) pharmacologic cardioversion agents or an agent against placebo. For each outcome, we performed network meta-analysis based on the frequentist approach. RESULTS: Forty-one trials (6013 patients) were included in our systematic review. Moderate confidence evidence suggests that i.v. vernakalant and flecainide have the highest conversion rate within 4 h, possibly allowing discharge from the emergency department and reducing hospital admissions. Intravenous and p.o. formulations of class IC antiarrhythmics (flecainide more so than propafenone) are superior regarding conversion rates within 12 h, while amiodarone efficacy is exhibited in a delayed fashion (within 24 h), especially if ranolazine is added. CONCLUSION: Our network meta-analysis identified with sufficient power and consistency the most effective antiarrhythmics for pharmacologic cardioversion over different time settings, with vernakalant and flecainide exhibiting a safer and more efficacious profile toward faster cardioversion.

Syncope associated with supraventricular tachycardia: Diagnostic role of implantable loop recorders.

Syncope represents a relatively uncommon symptom of supraventricular tachycardia (SVT). It is likely that an impaired autonomic vasomotor response to the hemodynamic stress of tachycardia is the determinant of hemodynamic changes leading to cerebral hypoperfusion and syncope. In this regard, tilt-table test may detect abnormalities in the autonomic nervous function and predict the occurrence of syncope during SVT. Electrophysiology studies may reproduce the SVT, distinguish it from other life-threatening ventricular tachyarrhythmias, and exclude other causes of syncope. Not infrequently mixed syncope mechanisms are revealed during the above diagnostic workup raising doubts about the operating mechanism in the clinical setting. In such cases of uncertainty, an implantable loop recorder, providing long-term cardiac monitoring, may play a pivotal role in the establishment of the diagnosis, confirming the association of an arrhythmic event with the symptom. Herein, we present four such cases with recurrent unexplained syncope finally attributed to paroxysmal SVT guiding them to a potentially radical treatment through radiofrequency catheter ablation.

Temporal changes of noninvasive electrocardiographic risk factors for sudden cardiac death in post-myocardial infarction patients with preserved ejection fraction: Insights from the PRESERVE-EF study.

BACKGROUND: Several noninvasive risk factors (NIRFs) have been proposed for sudden cardiac death risk stratification in post-myocardial infarction (post-MI) patients with preserved ejection fraction (EF). However, it remains unclear if these factors change over time. METHODS: We evaluated seven electrocardiographic NIRFs as they were described in the PRESERVE-EF trial in 80 post-MI patients with EF ≥ 40%, at least 40 days after revascularization and 1 year later. RESULTS: Mean patient age was 56 ± 10 years, and 88% were men. Mean EF was 50 ± 5%. The prevalence of (a) positive late potentials (27.5% vs. 28.8%, p = .860), (b) >30 premature ventricular complexes/hour (8.8% vs. 11.3%, p = .598), (c) nonsustained ventricular tachycardia (8.8% vs. 5%, p = .349), (d) standard deviation of normal RR intervals <75 ms (3.8% vs. 3.8%, p = 1.000), (e) QTc derived from 24-hr electrocardiography >440 ms (men) or >450 ms (women) (17.5% vs. 17.5%, p = 1.000), (f) deceleration capacity ≤4.5 ms and heart rate turbulence onset ≥0% and slope ≤2.5 ms (2.5% vs. 3.8%. p = 1.000), and (g) ambulatory T-wave alternans ≥65 µV in two Holter channels (6.3% vs. 6.3%, p = 1.000) were similar between the two measurements. However, five patients (6.3%) without any NIRFs during the first assessment had at least one positive NIRF at the second assessment and six patients (7.5%) with at least one NIRF at baseline had no positive NIRFs at 1 year. CONCLUSIONS: While the prevalence of the examined electrocardiographic NIRFs between the two examinations was similar on a population basis, some patients without NIRFs at baseline developed NIRFs at 1 year and vice versa, highlighting the need for risk factor reassessment during follow-up.

Arrhythmic risk stratification in post-myocardial infarction patients with preserved ejection fraction: the PRESERVE EF study.

AIMS: Sudden cardiac death (SCD) annual incidence is 0.6-1% in post-myocardial infarction (MI) patients with left ventricular ejection fraction (LVEF)≥40%. No recommendations for implantable cardioverter-defibrillator (ICD) use exist in this population. METHODS AND RESULTS: We introduced a combined non-invasive/invasive risk stratification approach in post-MI ischaemia-free patients, with LVEF ≥ 40%, in a multicentre, prospective, observational cohort study. Patients with at least one positive electrocardiographic non-invasive risk factor (NIRF): premature ventricular complexes, non-sustained ventricular tachycardia, late potentials, prolonged QTc, increased T-wave alternans, reduced heart rate variability, abnormal deceleration capacity with abnormal turbulence, were referred for programmed ventricular stimulation (PVS), with ICDs offered to those inducible. The primary endpoint was the occurrence of a major arrhythmic event (MAE), namely sustained ventricular tachycardia/fibrillation, appropriate ICD activation or SCD. We screened and included 575 consecutive patients (mean age 57 years, LVEF 50.8%). Of them, 204 (35.5%) had at least one positive NIRF. Forty-one of 152 patients undergoing PVS (27-7.1% of total sample) were inducible. Thirty-seven (90.2%) of them received an ICD. Mean follow-up was 32 months and no SCDs were observed, while 9 ICDs (1.57% of total screened population) were appropriately activated. None patient without NIRFs or with NIRFs but negative PVS met the primary endpoint. The algorithm yielded the following: sensitivity 100%, specificity 93.8%, positive predictive value 22%, and negative predictive value 100%. CONCLUSION: The two-step approach of the PRESERVE EF study detects a subpopulation of post-MI patients with preserved LVEF at risk for MAEs that can be effectively addressed with an ICD. CLINICALTRIALS.GOV IDENTIFIER: NCT02124018.