PO-05-141 ASSOCIATION OF INTERATRIAL BLOCK AND THE DEVELOPMENT OF ATRIAL FIBRILLATION AMONG PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY

Abstract

Atrial fibrillation (AF) is the most common sustained arrhythmia among those with hypertrophic cardiomyopathy (HCM), affecting 1 in 5 patients. The combination of HCM and AF is associated with an increased risk of stroke, heart failure, and mortality. Interatrial block (IAB) is a distinct electrocardiographic (ECG) pattern describing conduction delay between the right and left atria through Bachmann’s bundle. IAB has been identified as a predictor of AF across several disease states including congestive heart failure, valvular disease, and cardiac amyloidosis. To evaluate the association of IAB ECG findings with the development of AF among patients with HCM. We conducted a retrospective cohort study of adults with HCM who received care at our center from 8/17/1997 to 3/18/2021. Patients were included if they had an ECG reading prior to their AF diagnosis. We used multivariable logistic regression to identify whether IAB ECG findings (partial, advanced, or atypical) were associated with increased odds of AF in this patient population, after adjusting for potential covariates. Among 574 patients with HCM, 199 (34.7%) developed AF. The majority of AF was paroxysmal (75.4%). The average age in our cohort was 48 years and 220 (58.8%) were male. Among those who developed AF, 132 (66.3%) had an IAB ECG finding vs. 142 (37.9%) who did not develop AF. The most common abnormality was partial IAB (n=162, 28.2%). After adjusting for covariates, both partial and advanced IAB were significantly associated with the development of AF [aOR 4.15 (2.17 – 7.99; p <0.001) and aOR 5.39 (2.30 – 12.60; p <0.001), respectively]. Our analysis suggests that IAB ECG findings can serve as an important marker to identify those at risk of AF in HCM. IAB has demonstrated clinical prognostic significance and should prompt rigorous screening for AF in HCM patients. Our results should be validated by larger prospective studies.Tabled 1Baseline characteristics (N = 574)Atrial fibrillation (n = 199)No atrial fibrillation (n = 375)Age in years, mean (SD)47 (1.3)48 (0.9)Male, (%)144 (72.4)231 (61.6)BMI ≥ 30 kg/m2, (%)118 (59.3)175 (46.6)Paroxysmal atrial fibrillation, (%)Persistent atrial fibrillationPermanent atrial fibrillationLone episode atrial fibrillationNA150 (75.4)11 (5.5)19 (9.5)4 (2.0)15 (7.5)NANYHA functional class I, (%)NYHA functional class IINYHA functional class IIINYHA functional class IV48 (24.1)70 (35.2)80 (40.2)1 (0.50)129 (34.4)128 (34.1)118 (31.5)0 (0)Implantable cardioverter-defibrillator, (%)19 (9.5)27 (7.2)Systolic anterior motion, (%)155 (77.9)262 (69.9)Normal ECGPartial IABAdvanced IABAtypical IAB67 (33.7)84 (42.2)30 (15.1)18 (9.0)233 (62.1)78 (20.8)25 (6.7)39 (10.4)P-wave duration, ms, mean (SD)126.4 (1.5)117.7 (0.8)Ejection fraction ≥ 50%, (%)194 (97.5)374 (99.7)Logistic regression of ECG finding (N = 574)Odds ratio, 95% confidence intervalAdjusted odds ratio, 95% confidence interval∗The multivariable logistic regression adjusted for the following prespecified covariates: p-wave duration, gender, age, NYHA functional class, BMI ≥30 kg/m2, the presence of systolic anterior motion of mitral valveNormal ECGPartial IABAdvanced IABAtypical IABREF3.75 (2.48 – 5.65; p <0.001)4.17 (2.30 – 7.58; p <0.001)1.52 (0.81 – 2.85; p = 0.196)REF4.15 (2.17 – 7.99; p <0.001)5.39 (2.30 – 12.60; p <0.001)1.87 (0.93 – 3.75; p = 0.080)∗ The multivariable logistic regression adjusted for the following prespecified covariates: p-wave duration, gender, age, NYHA functional class, BMI ≥30 kg/m2, the presence of systolic anterior motion of mitral valve Open table in a new tab