Higher Frequency of Premature Atrial Contractions Correlates With Atrial Fibrillation Detection after Cryptogenic Stroke.

BACKGROUND: Covert atrial fibrillation (AF) is a major cause of cryptogenic stroke. This study investigated whether a dose-dependent relationship exists between the frequency of premature atrial contractions (PACs) and AF detection in patients with cryptogenic stroke using an insertable cardiac monitor (ICM). METHODS: We enrolled consecutive patients with cryptogenic stroke who underwent ICM implantation between October 2016 and September 2020 at 8 stroke centers in Japan. Patients were divided into 3 groups according to the PAC count on 24-hour Holter ECG: ≤200 (group L), >200 to ≤500 (group M), and >500 (group H). We defined a high AF burden as above the median of the cumulative duration of AF episodes during the entire monitoring period. We evaluated the association of the frequency of PACs with AF detection using log-rank trend test and Cox proportional hazard model and with high AF burden using logistic regression model, adjusting for age, sex, CHADS2 score. RESULTS: Of 417 patients, we analyzed 381 patients with Holter ECG and ICM data. The median age was 70 (interquartile range, 59.5-76.5), 246 patients (65%) were males, and the median duration of ICM recording was 605 days (interquartile range, 397-827 days). The rate of new AF detected by ICM was higher in groups with more frequent PAC (15.5%/y in group L [n=277] versus 44.0%/y in group M [n=42] versus 71.4%/y in group H [n=62]; log-rank trend P<0.01). Compared with group L, the adjusted hazard ratios for AF detection in groups M and H were 2.11 (95% CI, 1.24-3.58) and 3.23 (95% CI, 2.07-5.04), respectively, and the adjusted odds ratio for high AF burden in groups M and H were 2.57 (95% CI, 1.14-5.74) and 4.25 (2.14-8.47), respectively. CONCLUSIONS: The frequency of PACs was dose-dependently associated with AF detection in patients with cryptogenic stroke.

Ablation of ectopic atrial foci for successful management of symptomatic bradycardia: A case series (bradycardia and ectopic atrial beats).

Atrial premature contractions (PACs) that block at the atrio-ventricular (AV) nodal level and occurring in a bigeminal frequency are recognized as a cause of symptomatic bradycardia. Appropriate suppression of the PACs often results in restoration of a regular rhythm with resolution of bradycardia-related symptoms. We report a series of three patients with non-conducted bigeminal PACs arising from the mitral annulus that resulted in symptomatic bradycardia and who were referred for consideration of cardiac pacing. Focal ablation suppressed PACs restoring a normal heart rate and resolution of symptoms without resorting to cardiac pacing.

Atrial fibrillation is a marker of increased mortality risk in nonischemic heart failure-Results from the DANISH trial.

BACKGROUND: Atrial fibrillation (AF) in heart failure (HF) patients has been associated with a worse outcome. Similarly, excessive supraventricular ectopic activity (ESVEA) has been linked to development of AF, stroke, and death. This study aimed to investigate AF and ESVEA's association with outcomes and effect of prophylactic implantable cardioverter defibrillator (ICD) implantation in nonischemic HF patients. METHODS: A total of 850 patients with nonischemic HF, left ventricle ejection fraction ≤35%, and elevated N-terminal pro-brain natriuretic peptides underwent 24 hours Holter recording. The presence of AF (≥30 seconds) and ESVEA (≥30 supraventricular ectopic complexes (SVEC) per hour or run of SVEC ≥20 beats) were registered. Outcomes were all-cause mortality, cardiovascular death (CVD), and sudden cardiac death (SCD). RESULTS: AF was identified in 188 patients (22%) and ESVEA in 84 patients (10%). After 4 years and 11 months of follow-up, a total of 193 patients (23%) had died. AF was associated with all-cause mortality (hazard ratio [HR] 1.44; confidence interval [CI] 1.04-1.99; P = .03) and CVD (HR 1.59; CI 1.07-2.36; P = .02). ESVEA was associated with all-cause mortality (HR 1.73; CI 1.16-2.57; P = .0073) and CVD (HR 1.76; CI 1.06-2.92; P = .03). Neither AF nor ESVEA was associated with SCD. ICD implantation was not associated with an improved prognosis for neither AF (P value for interaction = .17), nor ESVEA (P value for interaction = .68). CONCLUSIONS: Both AF and ESVEA were associated with worsened prognosis in nonischemic HF. However, ICD implantation was not associated with an improved prognosis for either group.

Premature atrial complexes can predict atrial fibrillation in ischemic stroke patients: A systematic review and meta-analysis.

BACKGROUND AND PURPOSE: Several studies have explored premature atrial complexes (PACs) as high-risk factors for atrial fibrillation (AF) in ischemic stroke patients; however, the results were controversial. The aim of this systematic review and meta-analysis was to examine whether PACs can predict AF in ischemic stroke patients. METHODS: We comprehensively searched the published literature in PubMed, Embase, and Wiley-Cochrane library databases from inception through August 18, 2020. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were analyzed by the fixed-effect model or the random-effect model based on heterogeneity. RESULTS: We identified 12 eligible studies including 2340 stroke patients with a mean age of 65.9 years. PACs were highly associated with AF occurrence in stroke (pooled OR: 4.16, 95% CI: 3.06-5.65) and cryptogenic stroke patients (pooled OR: 3.72, 95% CI: 2.66-5.20). Subgroup analysis showed PAC presence and frequent PACs were correlated with stroke in AF patients (pooled OR: 3.72, 95% CI: 1.65-8.36 and pooled OR: 5.12, 95% CI: 3.12-8.41, respectively). Frequent PACs were identified as the risks for asymptomatic AF (OR: 6.18, 95% CI: 3.23-11.83) and future AF occurrence (OR: 3.71, 95% CI: 2.62-5.26) in stroke patients. The definition of frequent PACs was inconsistent, and was >70 beats/24 h based on Holter monitoring. CONCLUSIONS: PACs confer high risks for asymptomatic AF and future AF occurrence in stroke patients.

Frequent Premature Atrial Contractions in Cryptogenic Stroke Predict Atrial Fibrillation Detection with Insertable Cardiac Monitoring.

OBJECTIVE: To determine whether frequent premature atrial contractions (PAC) predict atrial fibrillation (AF) in cryptogenic stroke patients, we analyzed the association between frequent PACs in 24-h Holter electrocardiogram recording and AF detected by insertable cardiac monitoring (ICM). METHODS: We retrospectively analyzed a database of 66 consecutive patients with cryptogenic stroke who received ICM implantation between October 2016 and March 2018 at 5 stroke centers. We included the follow-up data until June 2018 in this analysis. We defined frequent PACs as the upper quartile of the 66 patients. We analyzed the association of frequent PACs with AF detected by ICM. RESULTS: Frequent PACs were defined as >222 PACs per a 24-h period. The proportion of patients with newly detected AF by ICM was higher in patients with frequent PACs than those without (50% [8/16] vs. 22% [11/50], p < 0.05). Frequent PACs were associated with AF detection and time to the first AF after adjustment for CHADS2 score after index stroke, high plasma -B-type natriuretic peptide (BNP; >100 pg/mL) or serum -N-terminal pro-BNP levels (>300 pg/mL), and large left atrial diameter (≥45 mm). CONCLUSION: High frequency of PACs in cryptogenic stroke may be a strong predictor of AF detected by ICM.

The clinical significance of premature atrial contractions: How frequent should they become predictive of new-onset atrial fibrillation.

BACKGROUND: Although previous studies reported frequent premature atrial contractions(fPACs) increased the risk of adverse cardiovascular outcomes, especially atrial fibrillation(AF), there is a substantial inconsistency between reports concerning the definition of fPAC. In this study, we aimed to investigate the relationship between fPAC and cardiovascular outcomes, especially AF. We further searched for a cutoff value of fPAC for prediction of AF. METHODS: We retrospectively analyzed the ambulatory 24-hr Holter monitoring records and 392 patients included. Frequent PAC was defined as more than 720 PAC/24 hr as used for frequent ventricular premature beats. Patients' baseline characteristics, echocardiographic variables and medical history were recorded. RESULTS: There were 189 patients with fPAC and 203 patients without fPAC. Patients with fPAC had more comorbidities in terms of hypertension, diabetes mellitus, coronary artery disease and congestive heart failure. CHA2DS2-VaSc was higher in patients with fPAC. Mean follow-up duration was 31 months, and the number of patients with new-onset AF during follow-up was significantly higher in fPAC group (22% vs. 5%, p < .001). fPAC was significantly and independently associated with new-onset AF and predicted AF with a cutoff value of 3,459 PAC/24 hr, and the risk of AF was 11-fold higher than those with <3,000 PAC/24 hr. In addition, an increased CHA2DS2-VaSc score was also associated with new-onset atrial fibrillation. CONCLUSION: In our study, we have demonstrated that fPAC is significantly associated with new-onset AF, and this association is the strongest among those patients who have more than 3,000 PAC in 24 hr.

Premature Atrial Contractions and Their Association with Stroke Features and Outcome.

BACKGROUND: Frequent premature atrial contractions (PACs) are associated with atrial fibrillation, stroke, and mortality. However, the cut-off value for PAC counts that could identify patients with different stroke features is unclear, and the association of PACs to outcome is not determined. METHODS: The study retrospectively included patients with acute ischemic stroke who had underwent both a 24 h Holter recording and a brain MRI in Taipei Veterans General Hospital from January 2015 to May 2016. Patients were categorized into four groups according to their PAC frequencies on 24 h Holter recording. We compared the clinical severity, neuroimage features, stroke subtypes, and functional outcome among the four groups of patients. RESULTS: Among the 278 patients, the lower, middle, and upper quartiles of the PAC counts were 23, 74, and 459.5, respectively. In contrast to the 1st quartile of patients, the 3rd (PAC 75-459/24 h) and the 4th (PAC ≥460/24 h) quartiles of patients had higher NIH Stroke Scale (NIHSS) at admission (p = 0.014 and p = 0.002, respectively). The frequencies of cryptogenic stroke were not different among the 4 quartiles of the patients, but cryptogenic stroke patients with ≥ 75PACs/24hours had higher stroke severity compared to those with PACs < 75counts/24 h (NIHSS 9.1 vs. 5.2, p = 0.043). There was an increased trend in infarcts of multiple vascular territories and in mortality at 1 year among the four groups of patients with increased PAC frequency (p = 0.045 and p = 0.002, respectively). The 4th PAC quartile was associated with poor functional outcome (modified Rankin Scale ≥ 4) at 3 months in univariate analysis (OR: 5.66, CI: 2.69-11.91, p < 0.001), but was not an independent predictor after controlling for initial stroke severity. CONCLUSIONS: PACs ≥ 75 counts/24 h was associated with higher clinical severity in patients with acute ischemic stroke.

Consequences of chronic frequent premature atrial contractions: Association with cardiac arrhythmias and cardiac structural changes.

INTRODUCTION: Frequent premature ventricular contractions (PVCs) can cause cardiomyopathy (CM). Postextrasystolic potentiation (PESP) and irregularity have been in implicated as triggers of PVC-CM. Because both phenomena can also be found in premature atrial contractions (PACs), it is speculated that frequent PACs have similar consequences. METHODS AND RESULTS: A single-center, retrospective study included all consecutive patients undergoing a 14-day Holter monitors (November 2014 to October 2016). Patients were divided into four groups by ectopy burden group 1 (<1%) and remaining by tertiles (group 2-4). Echocardiographic and arrhythmic data were compared between PAC and PVC burdens. In addition, a translational PAC animal model was used to assess the chronic effects of frequent PACs. A total 846 patients were reviewed. In contrast to PVCs, we found no difference in left ventricular ejection fraction (LVEF), end-systolic and end-diastolic dimensions and presence of CM (LVEF <50%) between different PAC groups. Multivariate regression analysis demonstrated that only PVC burden predicted low EF (odds ratio, 1.1; confidence interval, 1.03-1.13; P = .001). While there was a weak correlation between PAC burden and supraventricular tachycardia (SVT) episodes and atrial fibrillation (AF) burden (r = 0.19; P < .001), there was no correlation between PAC burden and LVEF or CM. Finally, atrial bigeminy in our animal model did not significantly decrease LVEF after 3 months. CONCLUSION: PAC burden is associated with increased AF and SVT episodes. In contrast to a high PVC burden, a high PAC burden is not associated with CM. Our findings suggest that heart rate irregularity and/or PESP may play a minimal role in the pathophysiology of PVC-CM.

Predictors of atrial ectopy and their relationship to atrial fibrillation risk.

AIMS: Premature atrial contractions (PACs) are known to trigger and predict atrial fibrillation (AF). We sought to identify the determinants of PACs and the degree to which PACs mediate the effects of established risk factors for AF. METHODS AND RESULTS: Predictors of baseline PAC frequency were examined using a Holter Study among 1392 participants in the Cardiovascular Health Study, a community-based cohort of individuals aged ≥65 years. Participants were then followed for their first diagnosis of AF. Independent predictors of PACs were identified, and the extent to which PACs might mediate the relationship between those predictors and AF was determined. The median hourly frequency of PACs was 2.7 (interquartile range 0.8-12.1). After multivariable adjustment, increasing age, increasing height, decreasing body mass index, and a history of myocardial infarction were each associated with more PACs. Regarding modifiable predictors, participants using beta-blockers had 21% less [95% confidence interval (95% CI) 9-30%, P = 0.001] and those performing at least moderate intensity exercise vs. lower intensity exercisers had 10% less (95% CI 1-18%, P = 0.03) PACs. Higher PAC frequency explained 34% (95% CI 22-57%, P < 0.0001) of the relationship between increasing age and AF risk and 27% (95% CI 10-75%, P = 0.004) of the relationship between taller height and AF risk. CONCLUSION: Enhancing physical activity and use of beta-blockers may represent fruitful strategies to mitigate PAC frequency. A substantial proportion of the excess risk of AF due to increasing age and taller height may be explained by an increase in PAC frequency.

Atrial ectopy after pulmonary vein isolation and left heart reverse remodeling in patients with atrial fibrillation.

BACKGROUND: Maintenance of sinus rhythm after pulmonary vein isolation (PVI) for atrial fibrillation (AF) is associated with left atrial (LA) and ventricular (LV) reverse remodeling, although the degree varies among individuals. We hypothesized that frequent premature atrial complex (PAC) after PVI may attenuate the left heart reverse remodeling benefited from maintenance of sinus rhythm. METHODS: We included 82 AF patients who underwent first-time PVI and 24-h Holter recordings at 6 months after PVI. All patients had no AF recurrence before this time. The number of PAC was categorized into tertiles: <90, 90-488 and >488 PACs/day. All patients underwent two-dimensional echocardiography and serum plasma B-type natriuretic peptide (BNP) measurement before and 6 months after PVI. LA reverse remodeling was defined as ≥15% decrease in LA volume index. RESULTS: There was no significant difference in the baseline characteristics among the PAC tertiles except for sex. Six months after PVI, LA volume index, LV mass index, and serum BNP levels were significantly decreased in lower and middle PAC tertiles (all P < .05), whereas no significant changes were observed in upper PAC tertile. Frequency of LA reverse remodeling was significantly lower in upper tertile of PAC compared with middle and lower tertiles (22.2%, 57.1%, and 59.3%, P < .001). Baseline LA volume index, changes in LV mass index, and the frequency of PAC were independently associated with LA reverse remodeling (all P < .05). CONCLUSIONS: Frequent PAC after PVI was associated with less left heart reverse remodeling in AF patients even without AF recurrence.

Features of Patients Aged 80 Years or Older with Embolic Stroke of Undetermined Source.

BACKGROUND: Embolic stroke of undetermined source has not been thoroughly investigated in older patients. In this study, we investigated the features of this condition in patients greater than or equal to 80 years of age. METHODS: All patients with acute ischemic stroke in our hospital underwent diffusion-weighted imaging, magnetic resonance angiography, T2-weighted imaging, and fluid-attenuated inversion recovery sequence imaging. Embolic stroke of undetermined source was defined as a radiologically confirmed nonlacunar brain infarct on diffusion-weighted imaging without (1) extracranial or intracranial atherosclerosis causing greater than or equal to 50% luminal stenosis in arteries supplying the ischemic area, (2) major-risk cardioembolic source, and (3) any other specific cause of stroke. We retrospectively identified consecutive patients hospitalized for acute ischemic stroke who met the embolic stroke of undetermined source diagnostic criteria and investigated patients' baseline and diagnostic findings. RESULTS: We divided 122 consecutive embolic stroke of undetermined source patients (median age: 73 years; 49 men, 73 women) into 2 groups by age at admission. Patients aged greater than or equal to 80 years had higher D-dimer and brain natriuretic peptide levels, more frequent premature atrial complexes/day in 24-hour Holter electrocardiography, and thicker maximum intima media thickness on ultrasound compared with patients aged less than 80 years (P < .05, U test). CONCLUSIONS: Our results suggest that high admission D-dimer and brain natriuretic peptide levels are associated with age of onset in patients with embolic stroke of undetermined source. Patients aged greater than or equal to 80 years tended to have more frequent premature atrial complexes and thicker maximum intima media thickness compared with patients aged less than 80 years.

Frequent premature atrial complexes as a predictor of atrial fibrillation: Systematic review and meta-analysis.

BACKGROUND: Frequent premature atrial complexes (PACs) are associated with higher morbidity and mortality. Recent studies suggest that frequent PACs are associated with new onset atrial fibrillation (AF). However, a systematic review and meta-analysis of the literature has not been done. We assessed the association between frequent PACs and new onset AF by a systematic review and a meta-analysis. METHODS: We comprehensively searched the databases of MEDLINE and EMBASE from inception to September 2017. Included studies were published cohort (prospective or retrospective) that compared new onset AF among patients with and without frequent PACs documented by Holter monitoring or 12-lead electrocardiogram. Data from each study were combined using the random-effects, generic inverse variance method of DerSimonian and Laird to calculate risk ratios and 95% confidence intervals. RESULTS: Twelve studies from 2009 to 2017 were included in this meta-analysis involving 109,689 subjects (9217frequent and 100,472 non-frequent PACs). Frequent PACs were associated with increased risk of new onset AF (pooled risk ratio = 2.76, 95% confidence interval: 2.05-3.73, p < 0.000, I2 = 90.6%). CONCLUSION: Frequent PACs are associated with up to three-fold increased risk of new onset AF. Our study suggests that frequent PACs in general population is an independent predictor of new onset AF.

Mild Hypokalemia and Supraventricular Ectopy Increases the Risk of Stroke in Community-Dwelling Subjects.

BACKGROUND AND PURPOSE: Stroke is independently associated with the common conditions of hypokalemia and supraventricular ectopy, and we hypothesize that the combination of excessive supraventricular ectopic activity and hypokalemia has a synergistic impact on the prognosis in terms of stroke in the general population. METHODS: Subjects (55-75 years old) from the Copenhagen Holter Study cohort (N=671) with no history of atrial fibrillation or stroke were studied-including baseline values of potassium and ambulatory 48-hour Holter monitoring. Excessive supraventricular ectopic activity is defined as ≥30 premature atrial complexes per hour or any episodes of runs of ≥20. Hypokalemia was defined as plasma-potassium ≤3.6 mmol/L. The primary end point was ischemic stroke. Cox models were used. RESULTS: Hypokalemia was mild (mean, 3.4 mmol/L; range, 2.7-3.6). Hypokalemic subjects were older (67.0±6.94 versus 64.0±6.66 years; P<0.0001) and more hypertensive (165.1±26.1 versus 154.6±23.5 mm Hg; P<0.0001). Median follow-up time was 14.4 years (Q1-Q3, 9.4-14.7 years). The incidence of stroke was significantly higher in the hypokalemic group (hazard ratio, 1.84; 95% confidence interval, 1.04-3.28) after covariate adjustments, as well as in a competing risk analysis with death (hazard ratio, 1.51; 95% confidence interval, 1.12-2.04). Excessive supraventricular ectopic activity was also associated with stroke (hazard ratio, 2.23; 95% confidence interval, 1.33-3.76). The combination of hypokalemia and excessive supraventricular ectopic activity increased the risk of events synergistically. Stroke rate was 93 per 1000 patient-year (P<0.0001) in this group (n=17) compared with 6.9 (n=480); 11 (n=81), and 13 (n=93) per 1000 patient-year in the groups without the combination. CONCLUSIONS: The combination of hypokalemia and excessive supraventricular ectopy carries a poor prognosis in terms of stroke.

Atrioventricular synchrony in the background of ventricular noise and undersensing.

The 24-hr electrocardiogram (ECG) interpretation in patients with double-chamber pacemakers may be challenging. The difficulty increases if not well-known pacemaker algorithm and device malfunction coexist. We show atrial synchronization pace (ASP) in a patient with ventricular lead damage. We provide detailed description of electrocardiogram and intracardiac electrogram. ASP may confuse 24-hr ECG monitoring interpretation, especially in patients with ventricular lead dysfunction.

Repeatability of ectopic beats from 48-hr ambulatory electrocardiography: The Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND: The purpose of this study was to characterize the repeatability of ectopic beats, defined by premature atrial contractions (PACs) and premature ventricular contractions (PVCs), on ambulatory electrocardiogram (aECG) monitoring and evaluate the effect of length of aECG monitoring on the repeatability estimates. METHODS: This analysis includes 95 randomly selected participants from the Atherosclerosis Risk in Communities Study (ARIC; 2011-2013). The participants wore a Holter monitor for two, 48-hr periods separated by a mean of 38 days following an identical, standardized protocol. We divided each 48-hr recording into 3-, 6-, 12-, and 24-hr recording periods and calculated intraclass correlation coefficients (ICCs) for PACs and PVCs and also as a percentage of the corresponding total of recorded beats per hour among these periods. RESULTS: All participants had ≥1 PAC during the 48-hr recordings, and only two participants had no PVCs. ICCs were >0.83 for all indices and recording lengths ≥12 hrs. ICCs were intermediate for 6-hr recordings (range 0.80-0.83) and lower for 3-hr recordings (range 0.74-0.80). The ratio of the between- to within-participant variation increased with recording length. CONCLUSION: Repeatability of PACs and PVCs was excellent for recording lengths of 6-24 hr and fair for 3 hr. Repeatability varies over shorter duration recordings within the 48-hr recording period, and thus the present results have implications for detection algorithms for ectopic beats and can facilitate epidemiologic and clinical applications in which knowledge of measurement variability and misclassification are needed.

Excessive Premature Atrial Complexes and the Risk of Recurrent Stroke or Death in an Ischemic Stroke Population.

BACKGROUND: Our aim was to investigate the association of premature atrial complexes and the risk of recurrent stroke or death in patients with ischemic stroke in sinus rhythm. METHODS: In a prospective cohort study, we used 24-hour Holter recordings to evaluate premature atrial complexes in patients consecutively admitted with ischemic strokes. Excessive premature atrial complexes were defined as >14 premature atrial complexes per hour and 3 or more runs of premature atrial complexes per 24 hours. During follow-up, 48-hour Holter recordings were performed after 6 and 12 months. Among patients in sinus rhythm, the association of excessive premature atrial complexes and the primary end point of recurrent stroke or death were estimated in both crude and adjusted Cox proportional hazards models. We further evaluated excessive premature atrial complexes contra atrial fibrillation in relation to the primary end point. RESULTS: Of the 256 patients included, 89 had atrial fibrillation. Of the patients in sinus rhythm (n = 167), 31 had excessive premature atrial complexes. During a median follow-up of 32 months, 50 patients (30% of patients in sinus rhythm) had recurrent strokes (n = 20) or died (n = 30). In both crude and adjusted models, excessive premature atrial complexes were associated with the primary end point, but not with newly diagnosed atrial fibrillation. Compared with patients in atrial fibrillation, those with excessive premature atrial complexes had similarly high risks of the primary end point. CONCLUSIONS: In patients with ischemic stroke and sinus rhythm, excessive premature atrial complexes were associated with a higher risk of recurrent stroke or death.

The circadian variation of premature atrial contractions.

AIMS: The aim of the study was to assess a possible circadian variation of premature atrial contractions (PACs) in a community-based population and to determine if the daily variation could be used to assess a more vulnerable period of PACs in predicting later incidence of atrial fibrillation (AF). METHODS AND RESULTS: We studied 638 subjects between the ages of 55 and 75 years from the Copenhagen Holter Study who underwent up to 48 h electrocardiogram recording. Follow-up on cardiovascular endpoints was performed in 2013 with a median follow-up time of 14.4 years. According to previous studies, two subgroups were studied based on a cut-off point of ≥720 PACs/day termed frequent PACs (n = 66) and not frequent PACs with <720 PACs/day (n = 572). Based on median values, a circadian rhythm could not be demonstrated in the population as a whole and the group without frequent PACs. However, a circadian variation was observed in the group with frequent PACs, who had the fewest PACs/h during the night with a nadir at 6 am and then reaching a peak value in the afternoon at 3 pm. Runs of PACs in all subjects showed a similar circadian variation. Both PACs/h and runs of PACs seemed to follow the daily variation in heart rate. After adjusting for relevant risk factors, the risk of AF was equal in all time intervals throughout the day. CONCLUSION: Premature atrial contractions showed a circadian variation in subjects with frequent PACs. No specific time interval of the day was more predictive of AF than others.

Electrocardiogram PR Interval Is a Surrogate Marker to Predict New Occurrence of Atrial Fibrillation in Patients with Frequent Premature Atrial Contractions.

The clinical significance of prolonged PR interval has not been evaluated in patients with frequent premature atrial contractions (PACs). We investigated whether prolonged PR interval could predict new occurrence of atrial fibrillation (AF) in patients with frequent PACs. We retrospectively analyzed 684 patients with frequent PACs (> 100 PACs/day) who performed repeated 24-hour Holter monitoring. Prolonged PR interval was defined as longer than 200 msec. Among 684 patients, 626 patients had normal PR intervals (group A) and 58 patients had prolonged PR intervals (group B). After a mean follow-up of 59.3 months, 14 patients (24.1%) in group B developed AF compared to 50 patients (8.0%) in group A (P < 0.001). Cox regression analysis showed that prolonged PR interval (hazard ratio [HR], 1.950; 95% CI, 1.029-3.698; P = 0.041), age (HR, 1.033; 95% CI, 1.006-1.060; P = 0.015), and left atrial (LA) dimension (HR, 1.061; 95% CI, 1.012-1.112; P = 0.015) were associated with AF occurrence. Prolonged PR interval, advanced age, and enlarged LA dimension are independent risk factors of AF occurrence in patients with frequent PACs.

Predictors of Occult Atrial Fibrillation in One Hundred Seventy-One Patients with Cryptogenic Transient Ischemic Attack and Minor Stroke.

BACKGROUND AND OBJECTIVE: Recent randomized studies have shown the potential of prolonged cardiac rhythm monitoring to detect silent paroxysmal atrial fibrillation (PAF) in patients with cryptogenic stroke. Our aim was to identify clinical and magnetic resonance imaging (MRI) factors that predict the detection of PAF during long-duration rhythm cardiac Holter (LDRCH) monitoring. METHODS: A retrospective analysis was performed using data from 171 patients with cryptogenic stroke or transient ischemic attack who underwent LDRCH monitoring (i.e., 21 days) from 2009 to 2013. Clinical, echocardiographic, and imaging predictors of atrial fibrillation (AF) were determined by multivariable analysis. RESULTS: PAF lasting more than or equal to 30 seconds was diagnosed in 26 of 171 (15%) patients. Median delay to first detected AF episode was 7 (interquartile range: 2-13) days. Four factors were independently predictive of PAF detection on LDRCH: age more than 70 years (odds ratio [OR], 4.6; 95% confidence interval [CI], 1.5-13.8); premature atrial complex on electrocardiogram (OR, 4.6; 95% CI, 1.1-19.6); left ventricular hypertrophy on transthoracic echocardiography (OR, 6.4, 95% CI, 1.6-26.4); and previous white matter lesions on brain MRI (OR, 4.2; 95% CI, 1.2-15.6). Recent brain infarction pattern on diffusion-weighted imaging was not associated with PAF detection on LDRCH. CONCLUSION: LDRCH is a noninvasive and inexpensive test with a high rate of AF detection in patients with cryptogenic stroke or transient ischemic attack. Occult PAF was more commonly diagnosed in older patients with premature atrial complex on the baseline electrocardiogram, left ventricular hypertrophy on echocardiography, and with previous white matter lesions on brain MRI.

Obstructive respiratory events and premature atrial contractions after cardioversion.

Recurrence of atrial fibrillation (AF) after electrical cardioversion (ECV) is increased in patients with obstructive sleep apnoea (OSA). In patients with persistent AF, with (n=40) and without (n=32) obstructive respiratory events (OREs) during sedation for ECV, we determined the occurrence of premature atrial contractions (PACs) before and after insertion of a nasopharyngeal tube. The influence of acute obstructive respiratory events on atrial electrophysiology after termination of AF was studied in pigs. Incidence of PACs directly after ECV was higher in patients with OREs compared to those without OREs (7±2 versus 1±1 per 10 s, respectively; p<0.01). Occurrence of PACs could be reduced by 79% by insertion of a nasopharyngeal tube. In a subsequent sleeping study, patients with OREs had higher apnoea-hypopnoea indices and more PACs during night. 16 patient with and four patients without OREs had a relapse of AF during 1 week after ECV (p<0.01). In pigs, acute OREs after 30 min of AF increased occurrence of PACs and vulnerability for reinduction of AF, which could be attenuated by atropine, beta-blockers and renal denervation. OREs are associated with increased occurrence of PACs and more early relapse of AF. OREs increase occurrence of PACs and vulnerability for reinduction of AF by sympathovagal imbalance.