Air Pollution and Coronary Vasomotor Disorders in Patients With Myocardial Ischemia and Unobstructed Coronary Arteries

Background: Coronary vasomotor abnormalities are important causes of myocardial ischemia in patients with nonobstructive coronary artery disease (NOCAD). However, the role of air pollution in determining coronary vasomotor disorders has never been investigated.

Objectives: We aimed to evaluate the association between long-term exposure to particulate matter 2.5 (PM2.5) and 10 (PM10), and coronary vasomotor disorders in NOCAD patients.

Methods: Patients with myocardial ischemia and NOCAD undergoing coronary angiography and intracoronary provocation test with acetylcholine were prospectively studied. Both patients with chronic myocardial ischemia and nonobstructive coronary arteries and myocardial infarction with nonobstructive coronary arteries (MINOCA) were enrolled. Based on each case's home address, exposure to PM2.5 and PM10 was assessed.

Results: We included 287 patients (median age, 62.0 years [IQR: 52.0-70.0 years], 149 [51.9%] males); there were 161 (56.1%) myocardial ischemia and nonobstructive coronary arteries and 126 (43.9%) MINOCA cases. One hundred seventy-six patients (61.3%) had positive provocation test. Exposure to PM2.5 and PM10 was higher in patients with a positive provocation test (P < 0.001). At multivariate logistic regression analysis, PM2.5 and PM10 were independent predictors of a positive provocation test (P = 0.001 and P = 0.029, respectively). Interestingly, among these patients, PM2.5 and PM10 were both independent predictors of MINOCA (P < 0.001 and P = 0.001, respectively) as clinical presentation, whereas PM2.5 was independently associated with the occurrence of epicardial spasm as opposed to microvascular spasm (P = 0.001).

Conclusions: Higher exposure to PM2.5 and PM10 in patients with myocardial ischemia and NOCAD is associated with coronary vasomotor abnormalities. In particular, PM2.5 is an independent risk factor for the occurrence of epicardial spasm and MINOCA as clinical presentation.