Frequency Of Premature Atrial Contractions Research Articles

Fetal premature atrial contractions: natural course, risk factors and adverse outcome.

Fetal premature atrial contractions (PAC) are usually benign but may be associated with congenital heart defect (CHD) and tachyarrhythmia, which in turn carry a risk of cardiac failure and fetal death. We aimed to explore the frequency of adverse outcome and to identify risk factors for tachyarrhythmia in pregnancies complicated by fetal PAC. This was a retrospective cohort study of fetuses diagnosed with PAC at two academic centers in Amsterdam, The Netherlands, between 2007 and 2022. Cases with a congenital anomaly and those with a prior diagnosis of CHD or other arrhythmias were excluded. M-mode and Doppler tracings were reanalyzed and the frequency of PAC was recorded. The incidence of the following adverse outcomes was examined: underlying CHD not identified at the 20-week fetal anomaly scan, tachyarrhythmia, other arrhythmia, administration of antiarrhythmic therapy and death. Risk factors for tachyarrhythmia were analyzed using odds ratios (OR). In 24.1% of 1439 referred cases, PAC resolved before confirmation at the fetal medicine unit (FMU). Of the 939 included cases with confirmed PAC, the total incidence of adverse outcome was 6.8% (64/939). CHD was diagnosed in 14 (1.5% (95% CI, 0.9-2.5%)) cases, of which eight were diagnosed prenatally and six postnatally. Compared with baseline, the incidence of CHD was higher in the presence of fetal PAC (OR, 1.8 (95% CI, 1.0-3.3); P = 0.034). Tachyarrhythmia occurred prenatally and/or postnatally in 32 (3.4%) cases, of which eight (25.0%) showed signs of cardiac failure, and in 23 (71.9%) cases, antiarrhythmic therapy was required. No cases of tachyarrhythmia led to fetal or infant death. Risk factors for tachyarrhythmia were PAC with short runs of supraventricular tachycardia (OR, 98.7), blocked PAC (OR, 30.3), PAC in bigeminy (OR, 21.8), frequent PAC (one per 5-10 beats) (OR, 6.9), signs of cardiac failure (OR, 14.2) and the presence of a foramen ovale aneurysm (OR, 5.0). PAC are generally benign and often resolve spontaneously. However, fetuses with an irregular heart rhythm should be referred for advanced ultrasonography, which should focus on classifying the type of PAC and risk of adverse outcome. When risk factors for tachyarrhythmia are identified, weekly fetal heart-rate monitoring is advised until resolution of the PAC. In the absence of risk factors, standard obstetric care may be sufficient, with additional instructions to report reduced fetal movements. Should tachyarrhythmia or cardiac failure develop, referral back to the FMU is indicated. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

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

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). 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. 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. The frequency of PACs was dose-dependently associated with AF detection in patients with cryptogenic stroke.

Association of non-sustained atrial tachycardia and its duration in 24-h Holter monitoring with embolic stroke of unknown source.

Although supraventricular ectopic beats (SVE), including premature atrial contractions (PACs) and non-sustained atrial tachycardia (NSAT), are frequent in the general population, some study results indicate that they are pathologic. SVE may predict undiagnosed atrial fibrillation or be associated with the embolic pattern of ischemic stroke. The aim of this study was to identify the indicators most associated with embolic stroke among the parameters that suggest the burden of SVE. A total of 1920 consecutive acute ischemic stroke (AIS) patients were enrolled from two university hospitals. We defined embolic stroke of unknown source (ESUS) and small vessel occlusion (SVO) etiologies using stricter criteria than the existing conventional criteria. We enrolled 426 (SVO: 310 vs. ESUS: 116) patients who met the inclusion criteria. In the 24-h Holter monitoring parameters, total number of PACs and PAC-to-total beat ratio were not significantly different between the two groups. However, NSATs were more frequent, and the duration of the longest NSAT was longer in the ESUS group. Multivariate logistic regression revealed that high brain natriuretic peptide levels, presence of NSAT, history of previous stroke, and the longest NSAT duration significantly correlated with the ESUS etiology. The presence of NSAT and its duration are more important indicators of embolic stroke than the frequency of PACs is. Therefore, considering secondary prevention in AIS patients with ESUS, 24-h Holter monitoring parameters, such as the presence of NSAT and its duration, could be considered as potential sources of cardio-embolism.

Abstract 10746: Left Atrial Strain and the Risk of Arrhythmias on Extended Ambulatory Cardiac Monitoring: The Multi-Ethnic Study of Atherosclerosis

Introduction: Abnormalities in left atrial (LA) function can be identified before the development of overt LA structural changes. Little is known about the relationship between LA mechanics and the risk of subclinical atrial and ventricular arrhythmias. Methods: 1,441 participants of the Multi-Ethnic Study of Atherosclerosis completed speckle-tracking echocardiography and Zio Patch monitoring from 2016-2018 (mean age 73 years, 52% female); participants in atrial fibrillation (AF) during echocardiography or cardiac monitoring were excluded. Absolute values of LA reservoir, booster pump, and conduit strain were measured. We evaluated associations of LA strain measures with atrial arrhythmias (presence of monitor-detected AF, AF burden, frequency of premature atrial contractions [PACs], frequency of supraventricular tachycardia [SVT] runs) and with ventricular arrhythmias (frequency of premature ventricular contractions, presence of non-sustained ventricular tachycardia [NSVT], frequency of NSVT runs). Primary analyses adjusted for demographic variables, blood pressure, smoking, diabetes, and clinical cardiovascular disease (4%). Results: Cardiac monitoring (median 14 days) detected AF in 3%. Each standard deviation (5.4%) lower (worse) LA reservoir strain was associated with a 64% higher risk of monitor-detected AF (95% CI 16-137%), 33% higher PAC frequency (95% CI 22-46%), and 15% higher SVT frequency (95% CI 7-24%). Adjustment for kidney function, NT-proBNP, LA volume, and LV ejection fraction and global longitudinal strain had little impact on associations. Findings were similar for LA booster pump strain and null for LA conduit strain (Figure). Associations of LA reservoir and booster pump strain with ventricular arrhythmias were completely attenuated after adjustment for LV function. Conclusions: In a multi-ethnic community-based cohort, abnormal LA mechanics may be an important risk factor for subclinical atrial arrhythmias.

Abstract 11836: Higher Burden of Supraventricular Ectopy is Independently Associated With Greater Risk of Dementia in Older Adults Without Atrial Fibrillation: The Atherosclerosis Risk in Communities Study

Introduction: In older adults without atrial fibrillation (AF), it is unclear if higher burden of supraventricular ectopy (SVE) is associated with dementia risk independent of cardiovascular risk factors and clinically documented stroke. Hypothesis: In older adults without AF, higher burden of SVE including premature atrial contractions (PAC) and atrial tachycardias (AT) are associated with a higher risk of dementia. Methods: Among 2167 participants (mean age, 79 years, 60% female, 26% Black) without adjudicated dementia, stroke or AF, at baseline (2016-17), AT and PAC were measured over 2 weeks by an ambulatory, continuous electrocardiogram recorder (Zio XT patch, iRhythm Technologies, Inc.). We quantified burden of PACs and ATs as: 1) natural log of frequency (episodes/day) due to skewed distributions, and 2) a dichotomous frequency measure, split at the median. Additionally, we dichotomized duration of the longest AT episode at the median. Dementia was adjudicated based on cognitive assessments through 2019 using the Clinical Dementia Rating scale at study visits or by telephone cognitive interviews, informant interviews, and ongoing linkage to medical records. We calculated relative risk of incident dementia using Poisson regression with robust error variance. Results: At baseline, median Zio XT patch wear time was 13.8 days (interquartile interval 13-14 days). Over 2 years of follow-up, 66 (3.0%) participants developed dementia. Higher frequency of AT and PAC (continuous or dichotomous) were associated with a higher risk of dementia independent of incident AF, stroke, and cardiovascular risk factors (Table). Conclusions: In older adults without AF, higher burden of SVE is associated with a greater risk of dementia independent of incident AF, stroke, and cardiovascular risk factors. Future research should define underlying mechanisms and evaluate the effect of lowering SVE burden on the risk of dementia in older adults with a higher SVE burden.

The Effects of Different Hormones on Supraventricular and Ventricular Premature Contractions in Healthy Premenopausal Women.

Background and Objectives: The effects of gender differences on cardiac parameters have been well-established. In this study, we aimed to evaluate the possible associations of plasma levels of different sex hormones with premature atrial or ventricular contractions in premenopausal women. Materials and Methods: We conducted a prospective study which included women in late reproductive age who presented with palpitations during an eight-month period. A 12-lead electrocardiography, a transthoracic echocardiogram, blood samples, and 24-hour rhythm Holter were conducted on the third day of the menstrual cycle. Results Overall, 93 healthy premenopausal women with a median age of 42 years were enrolled. QTc interval was within normal limits in all patients. The 24 h range of premature atrial contractions (PACs) and premature ventricular contractions (PVCs) was 0–6450 and was 0–21,230, respectively. The median number of PVCs was 540 and the median number of PACs was 212, respectively. In total, 51 patients (54.8%) had a frequency of PVCs > 500/24 h and 37 patients (39.8%) had a frequency of PACs > 500/24 h, respectively. No statistically significant association was shown between any hormone and the frequency of PACs. Regarding PVCs, patients with a PVCs frequency > 500/24 h had higher estradiol levels compared to patients with PVCs less than 500/24 h (median 60 pg/mL versus 42 pg/mL, p = 0.02, OR: 1.01). No association was found between PVCs and other hormones. Conclusions: In premenopausal healthy women, higher estradiol levels are independently associated with increased PVCs. This suggests that estradiol in late reproductive stages may exert proarrhythmic effects.

Activity levels influence frequency of premature atrial contractions

Abstract Background Frequent premature atrial contractions (PACs) are associated with substantially increased risk of atrial fibrillation (AF) and stroke, but PAC count varies substantially day-to-day. With the emergence of potential therapies for primary prevention of AF reliable estimation of PAC frequency is increasingly relevant, as is an understanding of PAC determinants. Purpose To determine the effect of daily activity and heart rate on an individuals' daily PAC count. Methods We included a random sample of patients 18–85 years without AF who recorded an ambulatory ECG for 7–31 days in the U.S.A during 2019 using a full-disclosure mobile cardiac telemetry device, and who had ≥500PACs on at least one recording day. PACs were algorithmically detected and manually verified. PAC count and activity was sampled for each individual and each recording day during daytime (06–22h). The effect of activity on daily PAC count was assessed in a negative binomial regression model including age, sex and with a random effect for individual, to account for confounding due to inter-individual differences. Results The study population consisted of 2,094 patients, of which 48% were men (Fig 1). Mean time spent in activity was 32% (standard deviation (SD 10%) for men and women 31% (SD 10%) for women (Fig 2). The median PAC count was 592 (inter-quartile range 1280). Beyond age, sex and intra-individual differences PAC frequency was determined by activity levels, (intercept 629 PACs; incidence rate ratio per 10 minute increase in activity 1.03, p&amp;lt;0.0001). A 1-hour increase in daily activity was associated with a 20% increase in daily PACs count. Conclusions Physical activity is associated with increased PACs counts, implying both that a reliable diagnosis of PAC frequency needs to be conducted during a person's habitual level of activity and that PAC frequency is modifiable. In-hospital assessments of PACs while patients are mainly inactive may underestimate PAC frequency. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): the Swedish Society For Medical Researchthe Swedish Heart and Lung Foundation Age and sex distributionActivity levels by sex

Abstract P036: Little Evidence Of Association Between Kidney Function And Subclinical Arrhythmias Measured By Extended Ambulatory Cardiac Monitoring: The Multi-Ethnic Study Of Atherosclerosis (MESA)

Introduction: Chronic kidney disease (CKD) patients are at high risk for atrial fibrillation (AF) and ventricular arrhythmias. Arrhythmias are often asymptomatic and not detected clinically, so the true prevalence among CKD patients is unknown. Extended ambulatory cardiac monitoring is a sensitive and unbiased method for detecting arrhythmias. Hypothesis: We assessed the hypothesis that impaired kidney function is associated with atrial and ventricular arrhythmias as measured by extended ambulatory cardiac monitoring. Methods: In the Multi-Ethnic Study of Atherosclerosis (MESA), kidney function was assessed at the 2016-2018 study visit: estimated glomerular filtration rate (eGFR) using the 2009 Chronic Kidney Disease Epidemiology Collaboration creatinine equation and urinary albumin-creatinine ratio (UACR). UACR was log 2 transformed for analysis. At the same visit, extended ambulatory cardiac monitoring was conducted for up to two 14-day periods per participant using the Zio Patch XT (iRhythm Technologies, Inc., San Francisco, CA). Device information was consolidated for participants with 2 devices, and 7 arrhythmia outcomes were studied: presence of monitor-detected AF (&gt;30 seconds), presence of subclinical AF (in those with no history of clinically detected AF), frequency of premature atrial contractions, frequency of runs of ≥ 4 beats of supraventricular tachycardia (SVT), frequency of premature ventricular contractions, presence of runs of ≥ 4 beats of ventricular tachycardia (VT), and frequency of runs of VT. Continuous outcome variables were natural log transformed. Analyses used logistic regression for binary outcomes and linear regression for continuous outcomes, adjusted for demographic and clinical risk factors. Results: A total of 1459 participants had eGFR measures and 1369 had UACR measures; 178 had a history of clinically detected AF. Mean (standard deviation (SD)) age was 74 (8) years; with 52% women. Median (interquartile range) kidney function measures were eGFR 77 (62, 88) ml/min/1.73 m 2 and UACR 6 (3, 18) mg/g, and total monitoring duration was 14 (14, 26) days. AF was detected in 7%, all but one participant had supraventricular ectopy, and 99% had ventricular ectopy. A doubling of UACR was associated with increased odds of monitor-detected AF (odds ratio 1.18; 95% confidence interval (CI): 1.06-1.32) while eGFR was not significantly associated. Neither eGFR nor UACR was associated with subclinical AF or with ventricular arrhythmias. The analysis of eGFR and frequency of runs of SVT yielded results opposite of the expected direction: a 10 ml/min/1.73 m 2 greater eGFR was associated with a 7% greater frequency of SVT (95% CI: 1%-12%). Conclusion: In summary, in a large population of older individuals across a wide range of kidney function, we found little evidence that impaired kidney function was associated with increased monitor-detected arrhythmias.

Abstract 15380: Association of Change in Body Mass Index With Premature Atrial Contractions Frequency and Atrial Fibrillation in Older Age: The Atherosclerosis Risk in Communities (ARIC) Study

Introduction: The proportions of obese and aging adults are rapidly growing. While obesity and advancing age are associated with atrial fibrillation (AF), data are limited on weight change in the elderly as a risk factor for premature atrial contractions (PACs)—which are known to precede AF—or AF. Hypothesis: Compared to a stable body mass index (BMI) over time, increasing BMI will be associated with a higher PAC frequency and AF in elderly participants in ARIC. Methods: We included N=2,070 ARIC participants [age mean ± SD 79 ± 4.5 years, 59% female] without known AF who attended visit 6 and wore an ambulatory ECG-monitoring device (Zio XT® Patch, iRhythm Technologies Inc.) for ≥48 hours. BMI change was defined as change between V5 (2011-13) and V6 (2016-17) and was categorized into 4 groups: &gt;10% decrease, 2 to 10% decrease, -2 to 2% change (stable BMI) and &gt; 2% increase. PAC frequency was defined as percent of beats that are PACs. Linear regression was used to evaluate the association between BMI change and % PAC. Incident AF was ascertained after V6 through 2018 from hospital discharge codes and death certificates. Logistic regression was used to evaluate the association between BMI change and incident AF. Results: Median PACs per hour were 8.84. Participants with &gt;2% BMI increase had 0.35% (95% CI: 0.06%-0.64%) higher frequency of PACs compared to those with stable BMI after multivariable adjustment (Table). After a mean (SD) follow-up of 19 (7) months, there were 82 incident AF cases. Compared to stable BMI, both &gt;2% BMI increase and 2 to 10% decrease were nonsignificantly associated with higher odds of AF compared with stable BMI after multivariable adjustment (Table). Conclusion: Increasing BMI in the elderly is associated with higher PAC frequency and is nonsignificantly associated with higher odds of AF compared to stable BMI. This finding suggests that weight management, which is currently emphasized in middle age, may also apply in late-life to prevent atrial arrhythmias.

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.

Advanced interatrial block: A predictor of covert atrial fibrillation in embolic stroke of undetermined source

AimsOne third of ischemic strokes are of unknown etiology. Interatrial block (IAB) is a marker of atrial electromechanical dysfunction that may predispose to the development of atrial fibrillation (AF). We hypothesized that IAB, especially in its advanced form, could be a marker of covert AF in patients with embolic stroke of undetermined source (ESUS). MethodsWe reviewed a single center cohort of ESUS patients with no prior history of AF. According to P-wave analysis of baseline ECG we distinguished 3 groups: normal P-wave duration (P-wave < 120 ms), partial IAB (P-IAB, P-wave ≥ 120 ms) and A-IAB (A-IAB, P-wave ≥ 120 ms with biphasic morphology in inferior leads). Follow-up was done 1, 6 and 12 months after discharge; then every 6 months. AF episodes, frequent premature atrial contractions (PACs) (>1%) and atrial tachyarrhythmias (runs of >3 consecutive PACs) were detected on 24 h Holter. The primary endpoint was new-onset AF detection on follow-up by any means. ResultsA high prevalence of both P-IAB (n = 30, 40%) and A-IAB (n = 23, 31%) was found in 75 ESUS patients. After a 521 day mean follow-up, 14 patients (19%) were diagnosed of AF. A-IAB independently predicted AF diagnosis (p =0.042) on follow-up. 24 h Holter analysis showed greater frequency of PACs and atrial tachyarrhythmia episodes in patients with IAB (p = 0.0275). ConclusionsIn this hypothesis-generating study, A-IAB in the setting of ESUS is an independent risk predictor of covert AF. Although additional randomized clinical trials are warranted, A-IAB identifies ESUS patients with advanced atrial disease that could potentially benefit from early oral anticoagulation in secondary prevention.

P3770Interatrial block: a prognostic factor for atrial fibrillation in cryptogenic stroke patients

Abstract Background Atrial fibrillation (AF) is a well-known risk factor for ischemic stroke. Interatrial block (IAB), resulting from a conduction delay in Bachmann's bundle, is an electrical abnormality that, especially in its advanced (A-IAB) form, has been associated with atrial fibrotic cardiopathy and remodeling, sharing a common pathologic substrate with AF. Therefore, IAB has been proposed as a marker of atrial electromechanical dysfunction that may predispose to the development of AF. We hypothesized that IAB could be a marker of AF in patients with cryptogenic stroke (CS). Methods We retrospectively screened a cohort of CS patients with no prior history of AF, and collected their demographic, cardiovascular risk factors and other co-morbidities, stroke severity and resultant functional disability (NIHSS and mRS scales), CHA2DS2-VASc score, baseline 12-lead ECG, transthoracic echocardiogram, and neuroimaging studies on admission. All patients underwent continuous ECG monitoring for at least 48h. Forty-eight (64%) patients underwent additional out-patient 24h Holter monitoring following hospital discharge. P-wave (PW) analysis of baseline ECG classified patients into three groups: normal p-wave duration (N, PW &lt;120 ms), partial IAB (P-IAB, PW ≥120 ms) and advanced IAB (A-IAB, PW ≥120 ms and biphasic morphology in leads DII, DIII and aVF). AF episodes (defined as irregular supraventricular arrhythmias without detectable PWs lasting &gt;30 s), frequent premature atrial contractions (PACs) (&gt;1%) and atrial tachyarrhythmia episodes (runs of &gt;3 consecutive PACs) were detected on 24h Holter readings. Ischemic brain lesions were classified as cortical, subcortical or lacunar in relation to their localization and maximal diameter. Results Out of the 80 consecutive CS patients identified, 5 were excluded due to poor quality ECG readings. A high prevalence of both P-IAB (n=30, 40%) and A-IAB (n=23, 30.7%) was found in the final analysis with 75 CS patients. No differences were found between demographics, cardiovascular risk factors and co-morbidities, NIHSS, mRS and CHA2DS2-VASc scores, left atrial size and left ventricular ejection fraction among the 3 ECG categories. Cortical ischemic brain lesions were more frequent in patients in the IAB groups than in the N ECG group. After a mean follow-up of 522 days, AF was clinically diagnosed in 13 patients (17%), with an increasing risk in accordance to the severity of the IAB (p&lt;0.05) (Figure 1A). 24h Holter readings showed greater frequency of PACs and atrial tachyarrhythmia episodes in patients with IAB (p&lt;0.05) (Figure 1B). Figure 1 Conclusions In CS, IAB is associated with a greater risk to develop AF and its presence identifies a subgroup of patients with probable atrial fibrotic cardiopathy that could potentially benefit from early oral anticoagulation in secondary prevention.

Recurrent Stroke With Rivaroxaban Compared With Aspirin According to Predictors of Atrial Fibrillation

The NAVIGATE ESUS randomized clinical trial found that 15 mg of rivaroxaban per day does not reduce stroke compared with aspirin in patients with embolic stroke of undetermined source (ESUS); however, it substantially reduces stroke risk in patients with atrial fibrillation (AF). To analyze whether rivaroxaban is associated with a reduction of recurrent stroke among patients with ESUS who have an increased risk of AF. Participants were stratified by predictors of AF, including left atrial diameter, frequency of premature atrial contractions, and HAVOC score, a validated scheme using clinical features. Treatment interactions with these predictors were assessed. Participants were enrolled between December 2014 and September 2017, and analysis began March 2018. Rivaroxaban treatment vs aspirin. Risk of ischemic stroke. Among 7112 patients with a mean (SD) age of 67 (9.8) years, the mean (SD) HAVOC score was 2.6 (1.8), the mean (SD) left atrial diameter was 3.8 (1.4) cm (n = 4022), and the median (interquartile range) daily frequency of premature atrial contractions was 48 (13-222). Detection of AF during follow-up increased for each tertile of HAVOC score: 2.3% (score, 0-2), 3.0% (score, 3), and 5.8% (score, >3); however, neither tertiles of the HAVOC score nor premature atrial contractions frequency impacted the association of rivaroxaban with recurrent ischemic stroke (P for interaction = .67 and .96, respectively). Atrial fibrillation annual incidence increased for each tertile of left atrial diameter (2.0%, 3.6%, and 5.2%) and for each tertile of premature atrial contractions frequency (1.3%, 2.9%, and 7.0%). Among the predefined subgroup of patients with a left atrial diameter of more than 4.6 cm (9% of overall population), the risk of ischemic stroke was lower among the rivaroxaban group (1.7% per year) compared with the aspirin group (6.5% per year) (hazard ratio, 0.26; 95% CI, 0.07-0.94; P for interaction = .02). The HAVOC score, left atrial diameter, and premature atrial contraction frequency predicted subsequent clinical AF. Rivaroxaban was associated with a reduced risk of recurrent stroke among patients with ESUS and moderate or severe left atrial enlargement; however, this needs to be independently confirmed before influencing clinical practice.

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

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. 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. 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.

Premature atrial contraction as a predictor of postoperative atrial fibrillation.

Postoperative atrial fibrillation occurs in 20%-60% of patients after cardiac surgery. Recently, premature atrial contraction has been considered an initiator of atrial fibrillation. This study evaluated whether the frequency of premature atrial contractions predicts the occurrence of postoperative atrial fibrillation. The subjects of this study were 70 patients with no history of atrial fibrillation who had undergone a 24-h Holter electrocardiogram before off-pump coronary artery bypass. Their records were reviewed and postoperative electrocardiograms and telemetry strips were analyzed for postoperative atrial fibrillation. Postoperative atrial fibrillation was documented in 22 (31.4%) patients. The frequency of preoperative premature atrial contractions was significantly higher in the postoperative atrial fibrillation group (4128 ± 7186 vs. 69 ± 221 beats/24 h, p < 0.001). The incidence of postoperative atrial fibrillation increased with the frequency of preoperative premature atrial contractions which occurred in 60% of patients in the upper 50th percentile group of preoperative premature atrial contractions. Multivariate logistic regression analysis revealed the upper 50th percentile group of preoperative premature atrial contractions (odds ratio = 67; 95% confidence interval: 5.51-838; p = 0.001) to be an independent predictor of postoperative atrial fibrillation. A high frequency of preoperative premature atrial contractions is a strong independent predictor of postoperative atrial fibrillation in off-pump coronary artery bypass.

Identification of “substrate fibrillators” and “trigger fibrillators” by pacemaker diagnostics

The population of patients likely to respond to selected pacing algorithms for maintenance of sinus rhythm is unknown. The purpose of this study was to identify patients with specific onset patterns of paroxysmal atrial fibrillation (AF). Dual-chamber pacemakers with advanced diagnostic functions were implanted in 112 patients with conventional indications for antibradycardia pacing and a history of paroxysmal AF. Pacemaker diagnostic data were analyzed after 97.5 +/- 40.9 days. According to the frequency of premature atrial contractions (PACs) during the 5 minutes before AF onset, patients were assigned to one of three groups: group A (high PAC activity), group B (moderate PAC activity), or group C (low PAC activity). AF burden was lower in group A (4.6% +/- 2.4%) than group B (15.8% +/- 3.0%, P = .003) and group C (15.5% +/- 3.1%, P = .003). Fewer AF episodes occurred in group A (2.1 +/- 1.3 per day) than group B (3.8 +/- 1.2 per day, P = .006). Mean AF episode duration was shorter in group A (11.4 +/- 10.2 hours) than group C (41.4 +/- 27.5 hours, P = .03). The coincidence of low PAC activity before AF onset, high AF burden, and extended arrhythmia episode duration appears to be the consequence of a high atrial substrate factor. In these "substrate fibrillators," the efficacy of pacing algorithms for maintenance of sinus rhythm may be limited. In contrast, "trigger fibrillators" exhibiting low AF burden despite high PAC incidence may represent the target population for specific PAC-suppressing pacing algorithms.

861 Overdrive pacing reduces the frequency of premature atrial contractions

861 Overdrive pacing reduces the frequency of premature atrial contractions

861 Overdrive pacing reduces the frequency of premature atrial contractions

861 Overdrive pacing reduces the frequency of premature atrial contractions

Anesthesia for electroconvulsive therapy.

Anesthesia for electroconvulsive therapy.

Electroconvulsive therapy-induced cardiac arrhythmias during anesthesia with methohexital, thiamylal, or thiopental sodium

Study Objective: To determine the frequency of electroconvulsive therapy (ECT)-induced arrhythmias under methohexital, thiamylal, or thiopental sodium anesthesia with and without atropine premeditation. Design: A randomized, double-blind study, placebo-controlled for atropine. Setting: The inpatient psychiatric unit at a university medical center Patients: Forty-nine patients scheduled for ECT. Interventions: Atropine 0.6 mg intravenously (IV) or an equal volume of normal saline IV was given before IV induction of anesthesia with methohexital 0.5 to 1.0 mg/kg, thiamylal 1.5 to 2.5 mg/kg, or thiopental sodium 1.5 to 2.5 mg/kg. Measurements and Main Results: Single-lead electrocardiogram (ECG) recordings were made for 1 minute before induction, during induction of anesthesia, and for 5 minutes after the ECT stimulus. Each ECG was evaluated for arrhythmias and evidence of ischemia in a blinded fashion. Blood pressure and ECG evidence of ischemia did not differ among the groups. Seizure duration was significantly (p < 0.05) prolonged by a mean of 5 seconds during methohexital anesthesia compared with thiopental sodium and thiamylal (47.6 ± 18.6 seconds, 42.7 ± 13.2 seconds, and 42.7 ± 15.2 seconds, respectively). The frequency of sinus bradycardia was decreased (p < 0.05) with methohexital (8%) compared with thiopental sodium (20%) and thiamylal (20%). The frequency of premature atrial contractions was decreased (p < 0.05) with methohexital (43%) compared with thiamylal (61%) but not with thiopental sodium (57%). The frequency of premature ventricular contractions was decreased (p < 0.05) with methohexital (27%) compared with thiopental sodium (44%) but not with thiamylal (40%). Atropine decreased the frequency of bradycardia (9% vs. 24%) and premature atrial contractions (47% vs. 61 %) and increased the frequency of sinus tachycardia (88% vs. 75%). Conclusions: These data suggest that anesthesia for ECT therapy should be induced with methohexital to minimize the possibility of potentially life-threatening cardiac arrhythmias. Atropine premedication may further decrease the frequency of premature atrial contractions and bradycardia, while increasing the frequency of tachycardia.