The provocation of coronary artery spasm

Prinzmetal's variant angina)(PVA). Circadian variation in response to hyperventilation

The study reports on the outcome of hyperventilation tests in a 57-year-old male with Prinzmetal's variant angina, formerly often complicated by ventricular fibrillation. It was found that hyperventilation for a period of 6 min after a delay of 4 to 6 min was followed by the development of ST-elevation and pain, but only when the test was performed in the morning, whereas the outcome of tests performed later in the day were negative. Pretreatment with calcium blockers, nifedipine or verapamil proved effective in preventing the anginal response to the test, also when it was performed in the morning. It is concluded that hyperventilation performed in the early morning, but not later in the day, may prove to be an effective and safe procedure for provoking Prinzmetal's variant angina, and that hyperventilation may be useful in the evaluation of the efficacy of drug therapy.

Ergonovine-induced alterations in coronary flow velocity preceding onset of occlusive spasm in patients without significant coronary artery stenoses

This study examined serial changes in coronary flow velocity to elucidate the dynamic change of coronary circulation during coronary spasm. Twenty patients with variant angina and 27 control patients were studied. Coronary flow velocity was monitored using a Doppler guidewire following intracoronary ergonovine administration. In the control group, diastolic flow velocity either did not change or increased slightly in response to ergonovine. However, in patients with variant angina, 2 patterns of flow velocity alterations were observed. In the first pattern, flow initially increased and then suddenly decreased (16 of 20 patients). In the second pattern, flow gradually decreased (3 of 20 patients). In the remaining patient, the coronary flow alteration could not be detected because of branch spasm. When abnormally high flow velocity was defined as a 100% increase in flow after ergonovine administration within 1 minute, and abnormally low flow velocity was defined as a 50% decrease in flow to diagnose variant angina, sensitivities of 35%, 75%, and 85% were noted if flow was measured 1.0, 2.0, and 3.0 minutes after ergonovine administration, respectively. These abnormal flow velocities were observed before ischemic ST changes appeared. In conclusion, in patients with variant angina, characteristic serial changes in coronary flow velocity occur before occlusive spasm. Variant angina may be diagnosed earlier by monitoring flow velocity rather than by monitoring for ischemic electrocardiographic changes.

Response of the coronary artery to a small dose of ergonovine in variant angina

The response of the coronary artery to a small dose (0.01 mg) of ergonovine was observed in nine patients without variant angina and in 10 patients with variant angina. Coronary angiograms were obtained before and after small and larger (routinely used) doses of ergonovine. With the larger dose, all 10 patients with variant angina had total or subtotal spastic occlusion accompanied by angina and ECG changes. Excluding the site of spastic occlusion produced by the larger dose of ergonovine, diameters of proximal, middle, and distal segments in each major coronary artery were measured before and after a small dose of ergonovine. The mean percentage of change in diameter (diameter before - diameter after a small dose of ergonovine)/diameter before a small dose of ergonovine X 100% in patients without variant angina was not significantly different from that in patients with variant angina (5.2 +/- 9.5% vs 7.0 +/- 11.9%, respectively). However, in patients with variant angina, a small dose of ergonovine produced a percentage of change in diameter of 39.8 +/- 15.3% at the site of spastic occlusion included by a larger dose of ergonovine, compared with that of 7.0 +/- 11.9% in the remaining non-spastic coronary arteries (p less than 0.05). These results indicate that patients with variant angina have local segments which respond differently to ergonovine from the remaining segments of coronary arteries. Clinically, this observation might be helpful in determining the angiographic positivity to ergonovine.

Coronary artery spasm: prevalence, clinical significance, and provocative testing

Recent clinical and laboratory observations indicate that coronary artery spasm may play a role in the pathophysiology of ischemic heart disease. The majority of patients with ischemic heart disease have coronary atherosclerosis. The prevalence of coronary artery spasm in these patients is unknown. However, current evidence suggests that patients with rest angina have a higher incidence of coronary artery spasm than do patients with reproducible effort angina. Coronary artery spasm may initiate or contribute to acute myocardial infarction, but recent evidence obtained in patients undergoing thrombolytic therapy during the early phases of myocardial infarction suggests that it is not a common occurrence. Although numerous examples of ventricular tachycardia and ventricular fibrillation occur during episodes of coronary artery spasm, the incidence of coronary artery spasm in association with sudden death is unknown. Provocative testing with ergonovine maleate reveals that the highest incidence of provocable coronary artery spasm is found in patients with rest angina. In patients with the syndrome of variant angina, coronary artery spasm is nearly always provocable.

Prinzmetal's variant angina

A series of 12 consecutive patients with Prinzmetal's variant angina is presented. There was a preponderance of males (eight/12) and individuals less than 60 years of age (nine/12). Delay in diagnosis was frequent, primarily due to difficulty in achieving a proper 12 lead ECG recording of the attack which often occurred late at night or in the early morning, subsiding within minutes. In some cases, moreover, ST-depression was observed in the ECG monitoring lead as a reciprocal manifestation of subepicardial ischaemia or due to incorrect polarity in the monitoring lead. The incidence of serious arrhythmias, AV-block and ventricular tachycardia was high (eight/12); two patients had to be DC-converted. Coronary arteriography revealed a spectrum from normal or nearly normal coronary arteries to single vessel disease. Nitroglycerin was well suited for treatment of acute attacks. Long-term treatment with calcium antagonists was effective and without serious side-effects. The follow-up time was from 8 months to 5 years (mean 2 years). It is concluded that Prinzmetal's variant angina as such is a rare disease, but that coronary artery spasm is most likely an important contributory factor in the clinical manifestations of coronary artery disease: arrhythmias, sudden death and myocardial infarction.