Importance of atrial contraction in hypertrophic obstructive cardiomyopathy: Implications for pacing therapy

Hypertrophic cardiomyopathy is a primary myocardial disease characterized anatomically by left ventricular (LV) asymmetric hypertrophy and pathophysiologically by normal or even supernormal systolic ejection performance contrasting with impaired diastolic function. Altered ventricular relaxation tends to reduce the contribution of rapid ventricular filling to total LV filling volumes. Consequently, the contribution of left atrial (LA) contraction can be significantly increased. In some patients LV filling, and thus stroke volume, critically depend upon atrial systole. These data may have important clinical implications especially in patients treated with permanent cardiac pacing. Preserving a fully efficient LA contribution to LV filling is probably a key point in those patients.