Introduction: A potential mechanism for impaired diastolic relaxation and stiffness in patients with heart failure with preserved ejection fraction (HFpEF) is the presence of coronary microvascular dysfunction (CMD). Invasive studies have demonstrated that HFpEF can be present in patients regardless of the presence or absence of echocardiographic diastolic dysfunction.
Hypothesis: We hypothesize that CMD is common in HFpEF with normal and abnormal echocardiographic diastolic function.
Methods: In a prospective study of HFpEF patients (n=30), clinical, echocardiographic, hemodynamic, and coronary physiology (CP) data were evaluated. CP parameters measured included coronary flow reserve (CFR) and index of microvascular resistance (IMR). Echocardiographic diastolic dysfunction (DD) was graded according to current ASE guidelines. Baseline clinical, echocardiographic, hemodynamic, and CP data were compared between grade 0 DD (n=10) and grade 1-3 DD (n=11), excluding patients with indeterminate DD grade (n=10).
Results: Age, gender, and comorbidities were similar in the grade 0 compared to grade 1-3 DD groups. Median BNP was higher in the grade 1-3 compared to the grade 0 DD group (462 vs. 98, p=0.012). All DD and strain measurements were significantly abnormal in the grade 1-3 compared to grade 0 DD groups, as were mean pulmonary artery, and left-sided filling pressures. Mean IMR was elevated and similar in patients with and without DD (30.5 vs. 27.9, p=0.58), however mean CFR was abnormal and lower in the grade 1-3 compared to grade 0 DD groups (2.05 vs. 3.30, p=0.053).
Conclusions: Although BNP, LV and left atrial strain, and LV filling pressures were higher in HFpEF patients with abnormal diastolic function compared to "normal" diastolic function, we found that elevated microvascular resistance is present in patients with HFpEF and "normal" diastolic function, but these patients have relatively preserved CFR.