IMPORTANCE OF ATRIAL CONTRACTION IN HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY - IMPLICATIONS FOR PACING THERAPY

Hypertrophic cardiomyopathy is a primary myocardial disease characteri zed anatomically by left ventricular (LV) asymmetric hypertrophy and p athophysiologically by normal or even supernormal systolic ejection pe rformance contrasting with impaired diastolic function. Altered ventri cular relaxation tends to reduce the contribution of rapid ventricular filling to total LV filling volumes. Consequently, the contribution o f left atrial (LA) contraction can be significantly increased. In some patients LV filling, and thus stroke volume, critically depend upon a trial systole. These data may have important clinical implications esp ecially in patients treated with permanent cardiac pacing. Preserving a fully efficient LA contribution to LV filling is probably a key poin t in those patients.