Prevalence, etiology, and characteristics of patients with type-2 acute myocardial infarction

Background In clinical practice, type-1 (coronary thrombosis) and type-2 (imbalance between oxygen demand and supply) acute myocardial infarction (AMI) are not clearly differentiated. The aim of this study was to evaluate the prevalence and etiology of type-2 AMI and compare its profile with that of type-1 AMI. Methods Patients admitted with ST-segment elevation AMI (STEMI) < 12 hours of symptom onset, and referred for coronary angiography, from 2009 to 2013, were analyzed. Results There were 1,960 patients included; 1,817 were analyzed, of whom 1,786 (98.3%) had type-1 AMI, and 31 (1.7%), type-2. All patients with type-2 AMI showed no significant coronary lesions, and 36% of the cases had apical dyskinesia. Type-2 AMI patients had, in general, a clinical and laboratory profile that was similar to those with type-1, except for the younger age, lower levels of myocardial necrosis markers, higher probability of having pre-TIMI 3 flow and higher left ventricular ejection fraction. At 30 days, mortality (3.2 vs. 9.0%; p = 0.23) and the occurrence of death, reinfarction, or need for target-vessel revascularization (3.2 vs. 13.0%; p = 0.09) were numerically lower in type-2 AMI. Conclusions Few patients with STEMI were classified as type-2; they had structural abnormalities, isolated or associated with the absence of significant lesions; showed little difference regarding the clinical and laboratory profile, and similar clinical outcomes at 30 days, when compared to patients with type-1 AMI.