Coronary microvascular dysfunction and right ventricular structure and function

Previous studies have suggested associations between coronary microvascular dysfunction (CMD) and alterations in left ventricular (LV) structure and function. Data are however scarce regarding the right ventricular (RV). In the context of CMD, the RV could be affected via mechanisms potentially involving ischemia from CMD, shared pathophysiological milieu leading to adverse ventricular remodeling, and/or increased afterload secondary to increased LV end-diastolic pressure or heart failure with preserved ejection fraction (HFpEF) with pulmonary hypertension. We evaluated the relationship between measures of RV structure/function and invasively measured CMD in individuals with suspected ischemia and no obstructive coronary artery (INOCA) disease. We included 297 participants from the WISE-HFpEF, WISE-preHFpEF and WISE-CVD cohorts, who underwent cardiac magnetic resonance imaging (CMRI) and coronary function testing to measure coronary flow reserve (CFR) in response to adenosine and coronary blood flow change in response to acetylcholine (triangle CBF). We assessed the correlation between RV parameters on CMRI and coronary microvascular function (CFR and triangle CBF). Participants had a mean age 54 +/- 11 years. Of them, 104 (39%) had hypertension, 31 (11%) had diabetes, and 18 (7%) had chronic obstructive pulmonary disease. Mean RV end-diastolic volume was 66.6 +/- 11.0 mL/m2, RV ejection fraction was 62.7%+/- 5.6% and RV longitudinal strain was -27.2%+/- 3.5%. We found no significant correlation between RV parameters and coronary microvascular function. This is the first study to report associations between invasively measured CMD and CMRI parameters of RV structure and function among patients with suspected INOCA. Despite a large sample size, we found no significant relationship between RV structure or function and CMD. These results suggest that RV abnormalities do not precede and are not concurrent with CMD in suspected INOCA participants. Longitudinal prospective studies are needed to evaluate if RV deterioration may occur later during the course of CMD and among patients with HFpEF.