Contributors to high left ventricular ejection fraction in women with ischemia and no obstructive coronary artery disease: Results from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) Study.

BACKGROUND: There are sex differences in left ventricular ejection fraction (LVEF) relevant to prognosis where women experience greater mortality at relatively higher LVEF compared to men, yet mechanistic understanding of this adverse prognosis is limited. Women with suspected ischemia with no obstructive coronary disease (INOCA) develop heart failure with preserved ejection fraction (HFpEF), yet contributors to LVEF remain largely unknown. METHODS: In 370 women with suspected ischemia with no obstructive coronary disease (INOCA) who prospectively underwent cardiac magnetic resonance imaging (CMRI), we investigated the contributions of LV morphology, function, and myocardial perfusion reserve on LVEF using univariate and multiple linear regression. RESULTS: A majority 71% of participants had high LVEF (>65%), followed by 24% having normal LVEF (55%-65%), and only 5% having low EF (<55%). Baseline characteristics were comparable among the 3 groups, with the exception of age which was 6 years higher in the high LVEF group (P < .01). Women in the high LVEF group also had the lowest LV cavity volume, greatest LV mass-volume ratio, and highest LV end-systolic elastance (all P < .05, adjusted for age, BMI, diabetes, and blood pressure). Myocardial perfusion reserve index was low in all groups (mean MPRI < 2.1) but was not significantly different across the spectrum of LVEF (P = .458). CONCLUSIONS: Taken together, these data demonstrate that the majority of women with suspected INOCA have elevated LVEF related to smaller, thicker ventricles with greater contractility. Future work is needed to better understand the specific mechanisms driving morphologic and functional changes in women with INOCA, and relations to longer-term HFpEF and mortality. CLINICAL TRIALS REGISTRATION: NCT02582021.

Impact of epicardial fat on coronary vascular function, cardiac morphology, and cardiac function in women with suspected INOCA.

INTRODUCTION: Epicardial fat is a metabolically active adipose tissue depot situated between the myocardium and visceral pericardium that covers ∼80% of the heart surface. While epicardial fat has been associated with the development of atherosclerotic coronary artery disease (CAD), less is known about the relationship between epicardial fat and coronary vascular function. Moreover, the relations between excess epicardial fat and cardiac morphology and function remains incompletely understood. METHODS AND RESULTS: To address these knowledge gaps, we retrospectively analyzed data from 294 individuals from our database of women with suspected ischemia with no obstructive coronary disease (INOCA) who underwent both invasive coronary function testing and cardiac magnetic resonance imaging (cMRI). Epicardial fat area, biventricular morphology, and function, as well as left atrial function, were assessed from cine images, per established protocols. The major novel findings were twofold: First, epicardial fat area was not associated with coronary vascular dysfunction. Second, epicardial fat was associated with increased left ventricular concentricity (ß= 0.15, p= 0.01), increased septal thickness (ß= 0.17, p= 0.002), and reduced left atrial conduit fraction (ß= -0.15, p= 0.02), even after accounting for age, BMI, and history of hypertension. CONCLUSIONS: Taken together, these data do not support a measurable relationship between epicardial fat and coronary vascular dysfunction but does suggest that epicardial fat may be related to concentric remodeling and diastolic dysfunction in women with suspected INOCA. Prospective studies are needed to elucidate the long-term impact of epicardial fat in this patient population.

Left atrial stiffness in women with ischemia and no obstructive coronary artery disease: Novel insight from left atrial feature tracking.

BACKGROUND: Women with signs and symptoms of ischemia and no obstructive coronary artery disease (INOCA) are at risk of heart failure with preserved ejection fraction (HFpEF); however, the mechanism for HFpEF progression remains unclear. Studies in INOCA have largely focused on left ventricular function. The left atrium serves an important role in maintaining transmitral flow, and is impaired in HFpEF; however, it remains unclear if left atrial function is impaired in INOCA. HYPOTHESIS: Left atrial function is progressively worse in INOCA and HFpEF compared to controls. METHODS: We compared 39 reference control subjects to 64 women with INOCA and 22 subjects with HFpEF. Left atrial strain was assessed by feature tracking using magnetic resonance cine images. RESULTS: Peak left atrial strain was reduced in HFpEF compared to controls (22.9 ± 4.8% vs 25.9 ± 3.2%, P < .01), but similar in INOCA (24.8 ± 4.5%) compared to HFpEF and controls (P = .18). However, left ventricular end-diastolic pressure (LVEDP) was elevated in 33% of INOCA participants, suggesting that left atrial stiffness (LVEDP/LA strain) is elevated in a large portion of women with INOCA. CONCLUSIONS: Taken together, we interpret these data to support our working hypothesis that INOCA is a pre-HFpEF state, with left atrial stiffness preceding overt left atrial dysfunction; representing a putative therapeutic target to prevent HFpEF progression in this at-risk population.