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.

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.

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).

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.

NCT02582021.