Dynamic limitation of coronary vasodilator reserve in patients with dilated cardiomyopathy and chest pain

Twenty-six patients with dilated cardiomyopathy and angiographically normal coronary arteries, 12 of whom gave a history of anginal chest pain, underwent noninvasive and invasive hemodynamic study. During treadmill exercise testing, patients with a history of angina demonstrated worse effort tolerance (7.4 ± 4.9 versus 13.6 ±5.1 minutes, p < 0.005) and a lower end-exercise systolic blood pressure-heart rate product (17.9 ± 3.4 versus 23.6 ± 4.9 mm Hg.beats/min × 103, p < 0.005) compared with patients without a history of angina.During rapid atrial pacing after ergonovine, 0.15 mg intravenously, 11 of the 12 patients with a history of angina experienced their typical chest pain, in contrast to only 1 of 12 patients without a history of angina. The angina group, compared with the rionangina group, had significantly lower great cardiac vein flow (118 ± 24 versus 160 ± 43 ml/min, p < 0.01), and higher coronary resistance(0.87 ± 0.21 versus0.66 ± 0.25mmHg.min/ml, p < 0.05), significant widening of the arterial — great cardiac vein oxygen difference and a significant fall in cardiac index during pacing. Further, ergonovine resulted in higher coronary resistance during pacing in the angina group compared with pacing alone (+ 0.16 ± 0.16 mm Hg min/ml, p < 0.01), in the absence of significant reduction in epicardial coronary artery luminal diameter. After dipyridamole, 0.5 to 0.75 mg/kg intravenously, to 21 patients, the 7 patients with a history of angina had significantly lower flow (149 ± 37 versus 218 ± 73 ml/min, p < 0.05) and higher coronary resistance (0.59 ± 0.09 versus 0.43 ± 0.17 mm Hgmin/ml, p < 0.05) than did the nonangina group.It is concluded that patients with dilated cardiomyopathy and chest pain unrelated to epicardial coronary artery disease exhibit impaired vasodilator responses to both metabolic and pharmacologic stimuli, and an increased sensitivity to the vasoconstrictor effects of ergonovine. Whether these findings are of etiologic or long-term prognostic significance is unknown