Angina with "normal coronary arteries". A misnomer

Myocardial ischemia due to vasospasm of small coronary arteries detected by methylergometrine maleate stress myocardial scintigraphy

BACKGROUND

Recently, several case reports have implicated vasospasm of small coronary arteries in vasospastic angina pectoris. Vasospasm of small coronary arteries was also considered from angiographic findings in patients with atypical chest pain. In Syrian hamster, vasospasm in small coronary arteries was considered to be the cause of dilated cardiomyopathy.

HYPOTHESIS

This study was undertaken to determine whether vasospasm in small coronary arteries can be induced by methylergometrine maleate stress thallium-201 (201Tl) myocardial scintigraphy.

METHODS

Twenty-five patients with chest pain, all of whom had intact coronary arteries, were studied. After intracoronary methylergometrine maleate injection, coronary arteriograms also looked normal in all cases. Thallium-201 myocardial scintigraphy was carried out immediately after intracoronary methylergometrine maleate injection in four patients with chest pain. In the remaining 21 patients with chest pain, methylergometrine maleate was given intravenously within up to 2 weeks before 201Tl myocardial scintigraphy.

RESULTS

In the intracoronary injection study, one patient had chest discomfort after methylergometrine maleate injection, and ST-segment elevation was observed on electrocardiogram (ECG). Of the 21 patients with chest pain, 11 patients felt angina-like chest pain after intravenous injection of methylergometrine maleate, but their ECGs showed no ischemic changes. Stress 201Tl myocardial scintigrams showed methylergometrine maleate-induced perfusion defects with complete redistribution in 3 of 4 patients in the intracoronary injection study and in 12 of 21 patients in the intravenous injection study. These findings suggest that vasospasm in small coronary arteries caused myocardial ischemia in 15 of 25 patients (60%) with chest pain.

CONCLUSION

Vasospasm in small coronary arteries may be involved in the myocardial ischemia of some patients with chest pain who do not show any large coronary artery vasospasm.

A possible model of the anginal syndrome with normal coronary arteriograms: microembolization of canine coronary arteries

To investigate whether disseminative coronary embolization with microspheres brings about a pathophysiological mimicking of the syndrome of exertional angina with a normal coronary arteriogram, 25 dogs were studied immediately and 2 weeks after the coronary embolization with microspheres 15 micron [2.5 X 10(5) or 5.0 X 10(5)/regional flow (ml/min)] and 25 micron [2.0 X 10(5)/regional flow (ml/min)] in diameter. Two weeks after embolization with the 15-micron microspheres, the resting coronary blood flow recovered to the control (preembolization) level with the absence of myocardial necrosis, but the coronary flow reserve was significantly lower. In ten dogs receiving the larger dose embolization (5 X 10(5)/regional flow (ml/min], lactate production or a marked decrease in lactate extraction was observed during rapid atrial pacing. In five dogs subject to 25-micron microsphere embolization, however, disseminative patchy myocardial necrosis was observed and the coronary flow reserve remained normal. These results indicate that the chronic state after microembolization with a large dose of 15-micron microspheres mimics the syndrome of exertional angina with a normal coronary arteriogram, whereas 25-micron microsphere embolization does not. Thus, the condition of some patients with a normal coronary arteriogram but with reduced coronary flow reserve may be attributable to microcirculatory disturbances in the coronary arterioles or smaller vessels. Moreover, we observed that the coronary flow at the induction of myocardial ischemia by pacing was much less than the reactive hyperemic flow. This discrepancy may be a characteristic feature in this syndrome.

Left ventricular dysfunction in patients with angina pectoris, normal epicardial coronary arteries, and abnormal vasodilator reserve

Thirty-three patients with chest pain despite angiographically normal coronary arteries underwent both coronary flow studies during pacing and resting and exercise gated blood pool scintigraphy. During atrial pacing after administration of ergonovine, those patients developing their typical chest pain demonstrated significantly lower great cardiac vein flow (97 +/- 31 vs 150 +/- 33 ml/min, p less than .001), higher coronary resistance (1.27 +/- 0.43 vs 0.77 +/- 0.18 mm Hg/ml/min, p less than .005), and less lactate consumption (30.5 +/- 22.0 vs 69.7 +/- 41.1 mM . ml/min, p less than .005) and a higher left ventricular end-diastolic pressure after pacing (20 +/- 4 vs 12 +/- 1, p less than .001) compared with those without pain and in the absence of significant luminal narrowing of the epicardial coronary arteries. The 26 patients with abnormal vasodilator reserve demonstrated reduced left ventricular ejection fraction during exercise (58 +/- 8%) compared with the seven patients with appropriate vasodilator reserve (66 +/- 4%, p less than .05) and with a group of 52 control patients of similar age and sex distribution and free of known heart disease (66 +/- 10%, p less than .001). In addition, 12 of the 26 patients with abnormal vasodilator reserve demonstrated exercise-induced regional wall motion abnormalities. Many of these patients also manifested impaired left ventricular diastolic filling at rest compared with the control subjects (peak filling rate 2.6 +/- 0.7 vs 3.2 +/- 0.7 end-diastolic volume/sec, p less than .005). Thus, patients with chest pain resulting from abnormal vasodilator reserve demonstrate abnormalities of left ventricular systolic and diastolic function suggestive of myocardial ischemia.

Ergonovine-induced esophageal spasm in patients with chest pain resembling angina pectoris

We studied the effect of ergonovine maleate (EM) on esophageal motor activity in 18 consecutive patients with angina-like chest pain. Significant coronary artery disease was excluded in each patient by cardiac catheterization studies. Baseline esophageal motility was abnormal in 12 patients (66%). After injection of EM, ten patients developed their typical chest pain at the onset of repetitive contractions. Thus, chest pain and esophageal dysfunction were clearly linked. Compared with saline injection, only the repetitive contractions were significantly increased after AM in these patients (P less than 0.01). Amplitude and duration of contractions were increased after EM, but not significantly. Due to potentially serious adverse effects, however, EM cannot be recommended for routine use as a provocative agent.

Verapamil in effort-induced angina pectoris in patients with normal coronary arteries

Two patients with classical effort-induced angina pectoris associated with abnormal ST-segment depression on graded exercise testing and normal coronary arteriograms are described. Both patients deteriorated during treatment with propranolol, and became asymptomatic during treatment with verapamil with normal graded exercise tests. Verapamil may thus improve an inadequate vasodilatatory response of the coronary vascular bed to effort.