RESUMO
Hypertrophic cardiomyopathy (HCM) is a complex disease that is sometimes difficult to control with medical therapy. Surgical treatment is highly effective but can be associated with significant morbidity and mortality. It has been suggested in uncontrolled studies that patients with obstructive HCM may improve symptomatically when treated with dual-chamber pacing. Several hypotheses have been suggested to explain this phenomenon, but the mechanism still remains unclear. Many recent randomized trials showed much less uniform effects on symptoms than previously reported. These results indicate the need for further comprehensive inquiry into the effects of pacing on HCM before it can be recommended for widespread use. The data on the benefit of pacing therapy in dilated cardiomyopathy are much more recent and limited. Initial optimistic reports have been only partially confirmed.