Heart rate variability findings as a predictor of atrial fibrillation in middle-aged population.

ABSTRACT

BACKGROUND: Autonomic nervous system modifies atrial electrophysiologic properties and arrhythmia vulnerability. METHODS: Heart rate (HR) variability, an indicator of cardiac autonomic regulation, was measured in 784 subjects (mean age 51 ± 6 years; 54% males) from a standardized 45-minute period in a study population (n = 1,045), which consisted of randomly selected hypertensive and age- and sex-matched control subjects at the time of recruitment in 1991-1992 (the OPERA study). RESULTS: During a mean follow-up of 16.5 ± 3.5 years, 76 subjects (9.7%) had developed symptomatic atrial fibrillation (AF), needing hospitalization. HR did not predict the occurrence of AF. Among the various spectral and time-domain HR variability indexes, only the low-frequency (LF) spectral component independently predicted AF. In the Cox regression analysis, the hazard ratio of reduced HR corrected LF (LFccv ≤ 1.59%, optimal cutoff from the ROC curve) in predicting the AF was 3.28 (95% CI 2.06-5.24; P < 0.001). In the multiple Cox regression model, including LFccv and other predictors of AF, such as age, gender, hypertension, history of coronary artery disease, systolic and diastolic blood pressure, body mass index, ß-blocking, angiotensin converting enzyme inhibitor and aspirin medication, left atrial size, left ventricular mass index, and left ventricular size obtained by echocardiography, only LFccv (hazard ratio 2.81; 95% CI 1.64-4.81; P < 0.001), age (P = 0.006), and systolic blood pressure (P = 0.02) remained as significant predictors of AF. CONCLUSIONS: Impaired LF oscillation of HR predicts new-onset AF in a middle-aged population emphasizing the important role of autonomic nervous system in the genesis of symptomatic AF.