Cardiac pacing in patients with dilated cardiomyopathy.

Studies of both the acute and chronic effects of permanent cardiac pacing in patients with dilated cardiomyopathy have produced contradictory results. Similarly, theoretically promising novel pacing techniques such as multisite, His bundle, and right ventricular outflow tract pacing have also yielded mixed results in preliminary studies. In general, at the present time, pacing therapy should be considered investigational for patients with dilated cardiomyopathy who do not have traditional bradycardia indications; nevertheless, pacing therapy may be useful in a small population of patients with dilated cardiomyopathy who have inappropriate timing of left ventricular and left atrial contraction. The beneficial effects of cardiac pacing in some patients with DCM cannot be dismissed out of hand; they must be explained. What is needed is clarification of the best methods to measure any benefits of this therapy: among the options are echocardiographically determined parameters of forward flow and AV valve function, exercise test parameters such as duration and O2 consumption, global and regional ejection fraction, functional classification, quality of life questionnaires, neurohumoral parameters such as plasma atrial natriuretic peptide and catecholamines, and, finally, disease progression and survival.