About 6- 15% of myocardial infarctions (heart attacks) are associated with nonobstructive coronary disease on angiography. This means that far less than 50% of heart attacks are due to blocked arteries. Also, these types of heart attacks occur more commonly in women.
A multinational study was done in which investigators enrolled 170 women with myocardial infarction with nonobstructive coronary arteries (MINOCA). These women were scheduled to undergo cardiac magnetic resonance imaging (MRI) and coronary optical coherence tomography (OCT). The OCT test uses infrared light to acquire cross-sectional images of the coronary artery using an intravascular catheter. This allows it to have a higher resolution than intravascular ultrasound.
In 145 women who underwent OCT, 67 had a possible or definite culprit lesion, such as plaque rupture or layered plaque. In 116 women who had an MRI, 62 had an ischemic (reduced blood flow) pattern of abnormalities and 24 had a nonischemic pattern, such as myocarditis or nonischemic cardiomyopathy (heart disease causing an enlarged heart). Overall, A cause for MINOCA was identified in 98 women, with an ischemic etiology in 74, and nonischemic in 24 women.
This study shows the benefit of using multiple imaging tests to identify the mechanism of MINOCA in most cases. It showed almost two thirds of cases related to an ischemic cause, despite the absence of severe obstructive coronary disease by angiography. Women tend to have microvascular disease which affects them four times more than men. They also have different symptoms of myocardial infarction than men. Both genders can exhibit symptoms of chest pain or discomfort but women are more likely to experience shortness of breath, nausea/vomiting and back or jaw pain. It’s best for physicians to order multimodality imaging especially for women with these symptoms to prevent the progression of a heart attack.
Reference: Reynolds, HR et al. Coronary optical coherence tomography and cardiac magnetic resonance imaging to determine underlying causes of MINOCA in women. Circulation 2020 Nov 14; [e-pub]. (https://doi.org/10.1161/CIRCULATIONHA.120.052008).