Short-term effects of right atrial, right ventricular apical, and atrioventricular sequential pacing on myocardial oxygen consumption and cardiac efficiency in patients with coronary artery disease.

OBJECTIVE To investigate the short-term effects of atrial, atrioventricular, and ventricular pacing on myocardial oxygen consumption, myocardial blood flow, and cardiac efficiency in patients with coronary artery disease. DESIGN Prospective study that started at the end of diagnostic coronary angiography in 13 patients and was performed during atrial, atrioventricular, and ventricular pacing for 5 min, in random order, at 20 beats/min more than the heart rate of the patient's positive exercise test. A Baim thermodilution catheter in the coronary sinus was used to measure myocardial blood flow and oxygen consumption and a pacing electrode at the right ventricular apex and a catheter in the pulmonary artery were used to estimate cardiac output. SETTING Referral cardiology centre. PATIENTS 13 patients with coronary artery disease (mean (SD) age 53(5) years). All the patients had a positive exercise test and most of them (77%) had left anterior descending coronary artery disease. RESULTS Mean (SD) cardiac output increased by 0.5(1.6) l/min during atrial pacing, increased by 0.1(1) l/min during atrioventricular pacing, and decreased by 0.8(1.2) l/min during ventricular pacing (P = 0.01 v atrial pacing, P = 0.03 v atrioventricular pacing). Diastolic pulmonary pressure increased by 6(4) mm Hg during atrial pacing, by 8.6(4) mm Hg during ventricular pacing (P = 0.02 v atrial pacing), and by 7.5(4.7) mm Hg during atrioventricular pacing. Changes in myocardial oxygen consumption and cardiac efficiency during the different pacing modes were similar. CONCLUSION Atrial, atrioventricular, and ventricular pacing had similar short-term effects on myocardial oxygen consumption, myocardial blood flow, and cardiac efficiency in patients with coronary artery disease. Ventricular pacing, however, did not increase cardiac output.