Prognostic significance of electrocardiographic findings in angina at rest. Therapeutic implications.

Abstract

SUMMARYNinety-five patients with angina at rest were observed in the coronary care unit. Eighty-one per cent presented concomitantly or had previously presented some other manifestations of coronary artery disease. These patients were divided into two subgroups. In subgroup 1 (40 patients), episodes of non-exertional angina were associated with a pattern of hyperacute subepicardial injury and, frequently, with ventricular arrhythmias. In subgroup 2 (55 patients), the episodes of angina at rest were attended by horizontal ST depression, isolated T wave inversion, or trivial ST-T changes. Coronary angiographic findings were similar in both subgroups.Symptoms regressed in only 9% of patients in subgroup 1 while they were receiving beta-receptor antagonists, whereas amiodarone alone or amiodarone with nifedipine was successful in 58%. Of these patients, 25% developed a myocardial infarction shortly after admission.In subgroup 2 patients, beta-blockers were successful in 61%. Amiodarone isolated or associated with nifedipine was successful in 55% of the patients in whom it was tried. Only 5% of patients in this subgroup developed a myocardial infarction during their hospital stay.It is concluded that: (1) observation of the electrocardiogram during spontaneous angina in patients with known atherosclerotic coronary heart disease may be of prognostic significance and may influence therapeutic decision. (2) Amiodarone by virtue of its anginal and antiarrhythmic properties may be particularly useful in the treatment of non-exertional angina.It has long been recognised that angina pectoris can occur spontaneously at rest and that different pathogenetic mechanisms may be involved in the production of this type of myocardial ischaemia.Recent studies have identified coronary vasospasm as one of the possible causes of the hyperacute attacks of ischaemia which occur at rest. 1-7 This new concept raises some questions regarding the therapeutic approach for patients with non-exertional angina.5Recently, in our coronary care unit we have observed 95 patients with angina at rest. The present report is concerned with the clinical features and results of treatment in these cases.

Effects of Chronic Oral Amiodarone on Left Ventricular Function, ECGs, Serum Chemistries, and Exercise Tolerance in Healthy Dogs

“…T-wave inversion has been reported in humans. 30,31 One case report, consistent with our observations, showed T-wave inversion associated with amiodarone toxicity in an attempt at suicide. 30 However, there are no reports in dogs about T-wave inversion.…”

Local platelet activation causes vasoconstriction of large epicardial canine coronary arteries in vivo. Thromboxane A2 and serotonin are possible mediators.

“…(Circulation 1989;79:154-166) It is currently believed that the pathophysiology of unstable angina is a primary reduction in coronary blood flow. [1][2][3][4][5][6] In particular, there is a growing body of evidence indicating that in most patients, unstable angina is the consequence of sudden restorations of flow. These alterations in coronary blood flow have been referred to as cyclic flow variations and are caused by transient formation of platelet thrombi at the site of the coronary stenosis and endothelial injury.14-17Subsequent studies from our laboratory have demonstrated that serotonin (5HT) and thromboxane A2 (TXA2) released from activated platelets are two important mediators of cyclic flow variations in this canine model15,17"8 and that the tissue concentration of 5HT and TXA2 is markedly elevated in the coronary artery at the site of the stenosis.…”