Heart rate turbulence and clinical prognosis in hypertrophic cardiomyopathy and myocardial infarction

Abstract

Short-term fluctuations in sinus cycle length after a single ventricular premature complex (VPC) have attracted considerable interest and has been termed heart rate turbulence (HRT). The onset and slope of HRT have each been reported to be independent and powerful predictors of clinical prognosis in patients with myocardial infarction (MI), but there are no data available for patients with hypertrophic cardiomyopathy (HCM). Thus the present study analyzed the 2 HRT variables to determine their prognostic value in HCM patients. Holter monitoring data were obtained from 104 HCM patients, 44 MI patients and 56 normal controls, from which singular VPCs followed by ≥20 normal sinus beats were isolated and the HRT onset and slope were automatically calculated. HRT onset and slope were abnormal in MI patients, but not in HCM patients, as compared with normal control subjects (onset -1.1±2.9, -2.1±3.4, -1.4±5.1%; slope 10.6±8.6, 18.0±13.9, 16.6±9.7 ms/beat, respectively). During the follow-up period of 27±10 months, 7 HCM patients and 10 MI patients either died from cardiac death or were hospitalized for congestive heart failure. In MI patients, HRT onset was higher and the HRT slope was lower in patients with cardiac events than in patients without (onset 1.1±2.7 vs -1.7±2.7%, p=0.011; slope 5.7±4.3 vs 12.0±9.0 ms/beat, p=0.028). In HCM patients, however, the HRT onset and slope were similar between patients with and without cardiac events (onset -2.0±2.0 vs -2.1±3.5%, p=0.98; slope 18.1±10.9 vs 18.0± 14.0 ms/beat, p=0.68). In conclusion, unlike MI patients, the HRT variables in selected HCM patients were not abnormal and failed to predict the clinical prognosis.