Heart Rate Variability and Development of Heart Failure
Is heart rate variability (HRV) independently associated with incident congestive heart failure (CHF) among older adults?
The study cohort was comprised of 1,401 asymptomatic participants in the Cardiovascular Health Study (CHS) with interpretable 24-hour baseline Holter recordings. The primary outcome of CHS was incident CHF. The study investigators compared HRV measures and premature ventricular contraction (PVC) counts between participants with (n = 260) and without (n = 1,141) incident CHF on follow-up. Using stepwise Cox regression, the investigators added significantly different parameters between groups to the components of the Health ABC Heart Failure score, a validated CHF prediction tool.
A total of 260 participants (19%) developed CHF during follow-up (median of 10.5 years). Participants who developed CHF were more likely to be male, older, and have a higher body mass index. The investigators found that increased ventricular ectopy counts and abnormal HRV measures from 24-hour Holter recordings (including decreased DFA1, decreased CV%, increased VLF, and abnormal heart rate turbulence onset) added to the predictive power of the Health ABC Heart Failure score to identify asymptomatic older adults at increased risk of developing CHF. The final model included components of the Health ABC score, PVC counts (adjusted hazard ratio [aHR], 1.12; 95% confidence interval [CI], 1.07-1.19; p < 0.001) and the following HRV measures: heart rate turbulence onset (aHR, 1.52; 95% CI, 1.11-2.08; p = 0.009), short-term fractal scaling exponent (aHR, 0.27; 95% CI, 0.14-0.53; p < 0.001), very low frequency power (aHR, 1.28; 95% CI, 1.02-1.60; p = 0.037), and coefficient of variance of NN intervals (aHR, 0.94; 95% CI, 0.90-0.99; p = 0.009). The investigators found that model C-statistic increased from 0.73 to 0.77, p = 0.0002, when HRV was included. In addition, in a low-risk subcohort, as defined by N-terminal pro–B-type natriuretic peptide ≤190 pg/ml, Health ABC components significantly associated with CHF were unchanged, and decreased DFA1 remained independently associated with incident CHF.
The authors concluded that abnormal HRV parameters were significantly and independently associated with incident CHF in asymptomatic older adults. When combined with increased PVCs, HRV improved the predictive power of the Health ABC score.
This is an important study because it suggests that HRV and PVCs are a predictor of HF. Prospective studies are needed to confirm these important findings and whether indeed HRV adds incremental value to PVCs as a predictor of HF (J Am Coll Cardiol 2015;66:101-9).
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