[Physiologic pacemaker therapy for drug-resistant heart failure in a patient with dilated cardiomyopathy and first-degree atrioventricular block: a case report].

This is a report of a 65-year-old man with end-stage dilated cardiomyopathy, and first-degree atrioventricular (AV) block, which had been resistant to intensive medical therapy and was eventually treated using a DDD pacemaker. The optimal AV interval setting was determined using invasive right heart catheterization and Doppler echocardiography. At a pacing rate of 92/min, an AV interval setting between 200 and 100 msec increased left ventricular filling and enhanced myocardial contractility. An AV interval setting of 50 msec further increased the left ventricular filling. However, this resulted in deteriorated left ventricular function. Based on these findings, the pacemaker was programmed with an optimal AV delay of 100 msec, a rate of 82-150 beats/min, and a DDD mode. This resulted in a good clinical course for 5 months after the therapy, but he eventually died from congestive heart failure 6 months after therapy. This case suggested that in patients with end-stage dilated cardiomyopathy and first-degree AV block, an optimal AV delay setting using a DDD pacemaker can improve deteriorated myocardial function. This probably increased left ventricular filling by efficiently utilizing the Frank-Starling mechanism.