Background: The underlying mechanisms causing myocardial ischemia in non-obstructive coronary artery disease (CAD) are incompletely understood. We tested whether the total coronary artery plaque burden, coronary tortuosity and left ventricular hypertrophy were independently associated with myocardial ischemia.
Material and methods: Study 1 included 108 patients with non-ST-elevation myocardial infarction (NSTEMI), and coronary artery plaque burden and tortuosity were assessed by quantitative invasive coronary angiography. Study 2 included 132 symptomatic patients with non-obstructive CAD by coronary computed tomography angiography (CCTA), and left ventricular hypertrophy was determined by echocardiography. In study 3, coronary artery plaque burden was assessed by quantitative CCTA in 125 symptomatic patients with non-obstructive CAD. Myocardial ischemia was determined using myocardial contrast echocardiography at rest in study 1 and during pharmacological stress in study 2 and 3.
Results: In study 1, coronary artery plaque burden was associated with severe myocardial ischemia independent of angiographic stenosis severity and cardiovascular risk factors. No association was found between coronary artery tortuosity and ischemia. In study 2, left ventricular hypertrophy was associated with myocardial ischemia, independent of cardiovascular risk factors and coronary calcium score. In study 3, coronary artery plaque burden estimated by CCTA was associated with myocardial ischemia, independent of left ventricular mass index, coronary calcium score and cardiovascular risk factors.
Conclusion: Coronary artery plaque burden was independently associated with myocardial ischemia both in NSTEMI and in symptomatic patients with non-obstructive CAD. Left ventricular hypertrophy was independently associated with myocardial ischemia in patients with non-obstructive CAD. These results suggest that the coronary plaque burden and left ventricular hypertrophy may contribute to myocardial ischemia independent of CAD severity
