Abstract 2392: Myocardial Infarction With Normal Coronary Arteries - a Current Perspective
Background: Myocardial infarction with normal coronary arteries (MINCA) has been recognized for many years, with a prevalence of 1 to 12% depending on the patient population. Various pathophysiologic mechanisms have been hypothesized, mainly coronary artery spasm and coagulation disorders. Most studies, however, were retrospective and not all patients had undergone emergency coronary angiography. This study sought to define prevalence and presumed mechanisms of MINCA in the era of emergency PCI by applying current criteria and modern diagnostic tools.
Methods and Results: Over a 2.5-year period, 63 MINCA were prospectively identified among 1081 patients with an acute coronary syndrome (ACS) undergoing emergency coronary angiography (prevalence 5.8%, 41 f, 22 m, age 65±15 years). MINCA was significantly more common in females (41/352 (11.6%) vs 22/729 (3.0%), p<0.001), and females were significantly older than males (70±13 vs 57±17 years, p<0.01). Diagnostic work-up included laboratory studies, transesophageal echocardiography, and cardiac MRI, as appropriate. MINCA presented as STEMI (n=43, 68%) or NSTEMI (n=20, 32%). The presumed MINCA mechanism was tako-tsubo-cardiomyopathy (CMP) in 27 (43%), acute myocarditis in 12 (19%), coronary embolism in 6 (9.5%) and myocardial bridging in 5 pat. (8%). Hypertrophic CMP and supraventricular tachycardia was identified in 3, severe anemia, coagulation anomalies and pulmonary embolism in 2, and pheochromocytoma in 1 pat. each. The most frequent MINCA diagnosis was tako-tsubo-CMP in females (22/41, 54%), and myocarditis in males (10/22, 45%). Although creatine kinase (338±440 vs 427±247 U/l, p<0.05) and troponin I (7.5±6.2 vs 17.4±13.1 ng/ml, p<0.05) were significantly lower in tako-tsubo-CMP compared to myocarditis, all tako-tsubo patients presented as STEMI (27/27 vs 7/12, p<0.001) with a significantly lower ejection fraction (53±15 vs 67±14%, p<0.01).
Conclusion: MINCA occurs in 6% of patients with ACS undergoing emergency coronary angiography and is significantly more common in elderly females. Contrary to previous reports, coronary artery spasm and coagulopathies appear to be rare. Tako-tsubo-CMP and myocarditis, from a current perspective, represent the most frequent MINCA mechanisms.