[Nitrates in unstable angina].
Unstable angina is an acute coronary syndrome between stable angina and myocardial infarction, with different clinical and laboratory features. Angiographically, these patients are more likely to have progression of coronary artery disease, vasospastic phenomena and intracoronary thrombus. Sudden plaque rupture, thrombus formation and the occlusion of an epicardial coronary vessel seem to be the underlying pathological mechanism. Patients with unstable angina are at an increased risk of major complications, especially fatal and nonfatal myocardial infarction, justifying an aggressive therapy in an Intensive Coronary Care Unit with beta-blockers, calcium antagonists and, in particular, nitrates, usually in association. The use of antiplatelet agents, namely aspirin, has been proved to be beneficial significantly reducing the risk of death and myocardial infarction. On the other hand, heparin and thrombolytic therapy are still a matter of some controversy, although the former is largely used in the acute phase. Coronary angiography should be done in all patients refractory to medical treatment to allow further management of the underlying coronary lesions by PTCA or coronary bypass surgery. However, some authors have advised a more aggressive attitude, performing the revascularization in an early phase. Randomized studies have shown that, with surgery, only patients with reduced left ventricular function may improve with the procedure, having a better two-year survival rate. Concerning PTCA, although the complication rate is somewhat higher than in the elective procedure, the probability of late infarction and death is significantly reduced in patients in which there was initial success.
Serviço de Cardiologia, Hospital de Santa Marta, Lisboa.
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Figueiredo
D000789:Angina, Unstable / Q000188:drug therapy*; D006801:Humans; D009566:Nitrates / Q000627:therapeutic use*
D009566:Nitrates
Nitratos na angina instável.