Pitfalls of Pacemaker Treatment for Hypertrophic Cardiomyopathy

Permanent dual chamber pacing with a shortened AV delay has been increasingly utilized as a therapeutic approach to the problem of drug refractory symptomatic obstructive hypertrophic cardiomyopathy. Such patients are a small proportion of the total patient population, potentially limiting the applicability of pacing. Attention has focused on the effect of pacing on indices of systolic function, primarily the left ventricular outflow tract gradient. The effects of pacing on diastolic function are uncertain, although recent acute catheterization studies suggest an adverse effect. Studies have concentrated on subjective symptomatic improvement. The available data on objective improvement suggests modest improvements at best. The limitations of current pacemakers together with the role of adjunctive techniques such as radiofrequency (RF) ablation of the atrioventricular node and coronary sinus pacing are also reviewed. Current ongoing randomized trials of DDD pacing in hypertrophic cardiontyopathy will resolve many issues, although data comparing myectonty versus pacing is as yet unavailable.