Holter Monitoring and Cardiovascular Events in Patients with Hypertrophic Cardiomyopathy

Abstract

Background: Patients with hypertrophic cardiomyopathy (HCM) have 3 distinctive modes of cardiovascular events: sudden death, heart failure, and stroke associated with atrial fibrillation. Holter monitoring provides various indexes, though little is known regarding their significance for the long-term prognosis except ventricular tachycardia as a risk marker for sudden death in HCM. Methods: Ambulatory Holter monitoring was performed in 106 HCM patients with normal sinus rhythm in clinically stable conditions. All patients were prospectively followed for the occurrence of sudden death, cardiovascular death and hospitalization for heart failure or stroke associated with atrial fibrillation. Results: Cardiovascular events occurred in 19 patients during an average follow-up period of 10.1 years. Cox proportional hazards regression analysis after adjustment for baseline characteristics showed that the risk of cardiovascular events was associated with a decrease in total QRS count (hazard ratio, 0.94 per 1,000 increase; p=0.011) and in average heart rate (hazard ratio, 0.93; p=0.026). These 2 predictors had little relationship to traditional predictors or the mode of cardiovascular events. Conclusions: Decreased heart rate on ambulatory Holter monitoring is an independent predictor for the long-term prognosis in patients with HCM. These simple indexes may add a new implication to the clinical practice of ambulatory Holter monitoring for the purpose of risk stratification in patients with HCM.