Identifying underlying causes and characteristics of type 2 myocardial infarction (T2MI), defined by an imbalance between demand and supply of oxygen without plaque disruption, and its distinction with type 1 myocardial infarction (T1MI), due to plaque rupture or erosion, remains a critical step to diagnosis and therapeutic strategies.

To comprehensively identify T2MI etiologic factors and to compare T2MI vs. T1MI characteristics.

Large prospective study in patients included from 2007 to 2017 in the RICO database, a French regional survey of acute MI. Cases were systematically adjudicated according to the 3rd universal MI definition criteria and prespecified causes of T2MI.

Among the 4572 patients included, 3710 (81%) had a T1MI and 862 (19%) a T2MI. Patients with T2MI were markedly older (77 vs. 67y, P<0.001), more frequently female, and had more comorbidities and was less frequently STEMI (24 vs. 52%, P<0.001) than in T1MI group. Clinical presentation was also more severe (median GRACE score: 171 vs. 143, P<0.001) and left ventricular ejection fraction more altered (50 vs. 55%, P<0.001). However, median troponin Ic peak was lower (3.5 vs. 17μg/L, P<0.001). Underlying mechanisms leading to T2MI highlighted 2 main patterns, characterized by 1) chronic predisposing factors including chronic anemia (10%) and severe aortic stenosis (7%) and 2) acute precipitating factors, of whom acute infections (39%), mainly respiratory tract infections, was the most frequent factor, followed by tachyarrhythmia (13%) and acute heart failure (10%). The most frequent acute or chronic causes were non-cardiogenic factors. Association of factors concerned 122 patients (14%).

In our large contemporary study, one of the largest to date, with a prospective T2MI identification, chronic anemia and severe aortic stenosis frequently predisposed to T2MI, and respiratory infections were the most frequent triggers.