Myocardial infarction with "angiographycally normal coronary arteries" myth or reality?

The leading cause of acute myocardial infarction (AMI) in patients with coronary heart disease is plaque rupture. Between 6% and 12% of AMI patients have angiographically normal coronary arteries. However, new procedures have demonstrated the limits of coronarography and challenged the existence of this situation. Angiograms may fail to detect minimal lesions whereas, in many cases, intravascular sonography reveals small atherosclerotic plaques. With the development of intravascular sonography and multislice computed tomography, the prevalence of myocardial infarction with normal coronary arteries has fallen to about 1%. Myocardial infarction with normal coronary arteries may be due to coronary vasospasm, hypercoagulable states, intense sympathetic stimulation, non atherosclerotic coronary disease, alcohol or cocaine abuse, and systemic diseases. In a series of 1205 AMI patients, we found no significant coronary disease in 45 patients, but intravascular sonography showed minimal intracoronary plaque in 21 of these cases. The 24 patients without significant lesions were young, had no risk factors for AMI without a prodrome, low peak creatine release, a small reduction in the left ventricular ejection fraction after thrombolysis or angioplasty, and good outcome at 26 months. The mechanisms of AMI in these 24 patients were coronary spasm, myocardial bridge, a prothrombotic state, contraceptive pill usage, and drug or alcohol abuse. The diferential diagnoses of these cases of AMI are acute myocarditis and stress cardiomyopathy, and apical left ventricular ballooning. Initial management is the same as for "conventional" AMI, including pain relief nitrates, antiplatelet agents, heparin, thrombolysis or angioplasty in the acute phase, and ACE inhibitors. Patients with spasm should receive calcium antagonists rather than beta-blockers. The prognosis of these patients is better than that of patients with atherosclerotic lesions. They nonetheless need close follow-up and strict secondary prevention measures, including smoking cessation and prevention of dyslipidemia and diabetes.