Cause of atrioventricular block in patients after heart transplantation.

BACKGROUND: The precise incidence and cause of atrioventricular block (AVB) after heart transplantation remain uncertain.

METHODS AND RESULTS: After surgery, immediate and follow-up electrocardiograms from 1047 consecutive patients who underwent heart transplantation were reviewed for AVB and correlated with clinical symptoms, laboratory data, rejection grade, and echocardiogram and coronary angiography findings. A total of 113 patients demonstrated various kinds of AVB; the incidence was 10.8%. First-degree AVB occurred in 87 patients, 37 of whom also demonstrated persistent atrial tachyarrhythmias (ATAs). In 30 patients, first-degree AVB occurred 7 days to 120 months after heart transplantation. Among those, 88% demonstrated cellular rejection, and 20% developed transplant coronary artery disease (TCAD). Fifty patients demonstrated first-degree AVB without ATA, 32 of whom developed AVB from operative day 7 to 156 months. The incidence of cellular rejection was significantly lower (36%, P<0.01), and the rejection was less severe. In 18 patients, AVB occurred early postoperatively (0-7 days), and most were secondary to surgical injury. Second-degree AVB Mobitz I occurred in six patients (four patients with TCAD and two patients undergoing percutaneous transluminal coronary angioplasty). One patient developed Mobitz II during coronary artery stenting. Complete AVB (CAVB) occurred in 19 patients. Nine episodes of CAVB occurred during endomyocardial biopsy or coronary angiography, and four occurred immediately after heart transplantation as the result of surgical insult.

CONCLUSION: These results indicate that first-degree AVB is causatively related to cellular rejection and TCAD-induced atrial conduction disturbance. Second-degree AVB and CAVB were mainly the consequences of surgical and catheter intervention injury.