Heart rate variability in left ventricular hypertrophy.

BACKGROUND

Electrocardiographic left ventricular hypertrophy and strain are associated with increased cardiac morbidity and mortality. Impaired cardiac autonomic function, assessed non-invasively by spontaneous heart rate variability on Holter monitoring, is associated with an increased 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 hypertrophy (94 with hypertension and 60 with aortic valve disease).

SETTING

Tertiary 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.

RESULTS

Patients with left ventricular hypertrophy had a higher left ventricular mass index (P < 0.001) and reduced heart rate variability (P < 0.001) compared with those of the controls. A continuous inverse relation was apparent between heart rate variability and left ventricular mass index (r = -0.478, P < 0.001). Heart rate variability was not affected by age, the presence of coronary artery disease in patients with left ventricular hypertrophy, or beta blocker treatment for hypertension. Multivariate analysis showed that left ventricular mass index is the most important determinant of heart rate variability.

CONCLUSION

Heart rate variability is significantly reduced in patients with left ventricular hypertrophy secondary to hypertension or aortic valve disease. 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 sudden death.