Coronary microvascular dysfunction in patients with acute coronary syndrome and non-obstructive coronary artery disease: a 10-year clinical follow-up study

Background and methods: Previous studies suggested that patients with myocardial infarction and non-obstructive coronary arteries (MINOCA) may have adverse clinical outcomes, but long-term follow-up has not hitherto been investigated. In this study we assessed whether non-invasive assessment of coronary functional abnormalities may help predicting long-term prognosis. We assessed coronary blood flow velocity (CBFV) response to ergonovine, adenosine and cold pressor test (CPT) by transthoracic Doppler echocardiography and performed exercise stress test (EST) in 30 patients (67 ± 10 years, 19 female) with MINOCA and 10 patients with non-cardiac acute chest pain (control group). Clinical conditions were assessed at a median follow-up of 10.3 years (interquartile interval, 8.4-10.5). Clinical endpoints included major adverse cardiovascular events (MACE) and all-cause mortality. Results: MACE occurred in 10 patients (33.3 %) and 1 control (9.1 %) (HR 4.20, 95 % C.I. 0.54-32.9, p = 0.17). Death occurred in 6 MINOCA patients (20 %), mainly from non-cardiovascular causes, whereas no death occurred in the control group (p = 0.37). In MINOCA patients, CBFV response to CPT was significantly associated with all-cause mortality (p = 0.046), whereas age (p = 0.084), CBFV response to adenosine (p = 0.096) and EST duration (p = 0.099) were of borderline statistical significance. At multivariable analysis, EST duration emerged as the only independent variable associated with mortality (p = 0.041). No variable was found to be predictive of long-term MACE in MINOCA patients. Conclusions: MINOCA patients present a sizeable global, but low cardiovascular mortality at long-term follow-up. Functional capacity seems the only variable independently predictive of global mortality, whereas non-invasive coronary functional tests seem unable to predict mortality and MACE.