Myocardial Function in Coronary Artery

Right atrial pacing was performed in 21 patients with and 10 patients without coronary artery disease (CAD). The values for the control (C) and maximum paced (P) heart rate were similar in all patients. During pacing cardiac output did not change, and mean arterial pressure remained constant except for a slight increase during pacing-induced angina pectoris in 11 patients with CAD. Left ventricular end-diastolic pressure (LVEDP) decreased in the normal subjects (C = 9 + 1, P = 3 + 1 SEM mm Hg) and in all 10 patients with CAD who did not develop angina (C = 15 + 3, P = 5 1 mm Hg). In 11 patients with CAD, developing angina, LVEDP did not decrease before pain occurred (C= 9 + 1, P = 9 + 2 mm Hg) and increased during induced angina (P = 14+ 3 mm Hg). Pacing ventricular function curves (VFC) relating induced changes in LVEDP and stroke work were abnormal in five of 10 patients with CAD and without induced angina when compared to the normal subjects. In patients developing angina, pacing VFC were normal in five of 10 before pain and then became abnormal in four of these five when angina occurred. Atrial pacing may be used to evaluate ventricular function and may demonstrate abnormalities in patients with CAD even in the absence of pacing-induced angina. Angina pectoris is usually associated with an overall decrease in myocardial function.