HEART-RATE-VARIABILITY IN LEFT-VENTRICULAR HYPERTROPHY

Background-Electrocardiographic left ventricular hypertrophy and strai n are associated with increased cardiac morbidity and mortality. Impai red cardiac autonomic. function, assessed noninvasively by spontaneous heart rate variability on Holter monitoring, is associated with an in creased risk of sudden death after myocardial infarction. Aim-To study the effect of left ventricular hypertrophy on heart rate variability. Patients-36 controls and 154 patients with left ventricular hypertrop hy (94 with hypertension and 60 with aortic valve disease). Setting-Te rtiary referral centre. Methods-Heart rate variability was measured on 24 h Holter recordings by non-spectral methods. Left ventricular mass index and fractional shortening were measured by echocardiography. Re sults-Patients with left ventricular hypertrophy had a higher left ven tricular mass index (P < 0.001) and reduced heart rate variability (P < 0.001) compared with those of the controls. A continuous inverse rel ation was apparent between heart rate variability and left ventricular mass index (r = - 0.478, P < 0.001). Heart rate variability was not a ffected by age, the presence of coronary artery disease in patients wi th left ventricular hypertrophy, or P blocker treatment for hypertensi on. Multivariate analysis showed that left ventricular mass index is t he most important determinant of heart rate variability. Conclusion-He art rate variability is significantly reduced in patients with left ve ntricular hypertrophy secondary to hypertension or aortic valve diseas e. A continuous inverse relation exists between heart rate variability and left ventricular mass index. Impaired cardiac autonomic function in left ventricular hypertrophy may contribute to the mechanism of sud den death.