Effect of programmed ventricular stimulation on myocardial lactate extraction in patients with and without coronary artery disease

The arterial-coronary sinus lactate difference was measured in 17 patients after each step of a programmed ventricular stimulation protocol consisting of single, double, and triple extrastimuli, first at a basic drive cycle length of 600 msec, then at 400 msec, with an inter-train interval of 4 seconds. Four patients had no structural heart disease, four had an idiopathic dilated cardiomyopathy, and nine had coronary artery disease with a significant stenosis in at least one branch of the left coronary artery. Net myocardial lactate production during programmed ventricular stimulation was observed in three patietns with coronary artery disease, but not in any patient without coronary artery disease. Among the patients who had coronary artery disease, net myocardial lactate production generally occurred in the patients who had more severe coronary artery disease. Exercise-induced ischemia, as demonstrated by a stress thallium-201 test, did not correlate with myocardial lactate production during programmed ventricular stimulation. Programmed ventricular stimulation, with a stimulation protocol typically used in many electrophysiology laboratories, is capable of inducing myocardial ischemia in at least some patients who have coronary artery disease. This finding suggests that myocardial ischemia may potentially influence the results of programmed ventricular stimulation in some patients with coronary artery disease.