Coronary microvascular dysfunction and findings of heart failure with preserved ejection fraction in patients with microvascular angina

Background: Coronary microvascular dysfunction (CMD) may cause symptoms of myocardial ischemia (microvascular angina, MVA), but recent studies suggested that it might also contribute to the syndrome of heart failure with preserved ejection fraction (HFpEF). In this study we assessed the relation of CMD with findings of HFpEF in MVA patients. Methods: We enrolled 36 consecutive patients with MVA, in whom we assessed: 1) coronary blood flow (CBF) response to adenosine and cold pressor test (CPT) by colour-Doppler echocardiography of the left anterior descending coronary artery; 2) complete echocardiographic examination; 3) N-terminal-pro-B-natriuretic peptide (NTproBNP); 4) grade of dyspnea by the modified Medical Research scale. Results: Among patients, 15 had definite HFpEF findings (group 1), 12 had equivocal HFpEF findings (group 2) and 9 had no evidence of HFpEF findings (group 3). Group 1 patients were older, had more cardiovascular risk factors and higher NT-proBNP levels (p=0.018), and showed a higher prevalence of diastolic dysfunction. Left ventricle dimensions and systolic function, however, did not differ among groups. Dyspnea was also not significantly different among groups (p=0.19). CBF to adenosine was 1.85±0.47, 1.78±0.40 1.49±0.32 in group 1, 2 and 3, respectively (p=0.13). Similarly, CBF response to CPT was 1.57±0.4, 1.49±0.2 and 1.45±0.3 in the 3 groups, respectively (p=0.74). Both CBF response to adenosine and CPT showed no relation with the severity of dyspnea symptoms. Conclusions: Our data suggest that in patients with MVA there is no relation between the grade of impairment of coronary microvascular dilatation and findings of HFpEF.