Atrial pacing in coronary artery disease

Abstract

Atrial pacing was performed in thirty-one patients with coronary artery disease (CAD) and the effects compared to those in ten normal subjects. Control (C) and pacing (P) heart rates were similar in both groups, and mean arterial pressures and cardiac outputs were unchanged by pacing except for a slight rise in arterial pressure during induced angina pectoris. Stroke volume and stroke work decreased in each group and left ventricular end-diastolic pressure (LVEDP) declined in the normal subjects. In patients with CAD, LVEDP declined in those who did not experience angina and was unchanged in the group with induced angina. Angina was induced in eighteen of thirty-one patients with CAD, and ischemic S-T depression occurred in thirteen of these eighteen and in five of thirteen without pain. Angina and changes in the S-T segment were most common with the most severe CAD. Pacing ventricular function curves (VFCs) relating pacing-induced changes in LVEDP and stroke work were abnormal in seventeen of thirty-one patients with CAD prior to angina and were abnormal in sixteen of eighteen during angina. VFCs were abnormal in eleven of twelve patients with elevated control LVEDP and in thirteen of sixteen with generalized left ventricular angiographic abnormalities. Sudden pacing interruption caused an “overshoot” in LVEDP in nine of twenty-three instances, and this was associated with abnormal VFCs, but eight of fourteen patients with no “overshoot” also had abnormal VFCs. The results of this study are compared to previously published results, and the clinical usefulness and investigative value of atrial pacing are discussed.