The association of coronary microvascular dysfunction and cardiac maladaptation with clinical outcomes in heart...

Accumulating evidences have suggested a pathophysiological link between coronary microvascular dysfunction (CMD) and heart failure with preserved ejection fraction (HFpEF). The clinical relevance and prognostic impact of myocardial blood flow (MBF) using single-photon emission computed tomography (SPECT) among HFpEF patients remain unexplored clearly.

Fifty-five patients with HFpEF and 48 controls were prospectively enrolled. All underwent dynamic myocardial perfusion imaging with (99 m) Tc-sestamibi at rest and a stress test at peak with dipyridamole. MBF and myocardial flow reserve (MFR) parameters were obtained after perfusion and further related to cardiac structural and advanced functional strain measures using echocardiography and clinical outcomes.

CMD (defined as global MFR <2.5) was more prevalent in HFpEF than in control (71 % vs 16.7 %). Patients with HFpEF had worse longitudinal strain indices, lower post-stress MBF (2.37 ± 0.78 vs. 3.30 ± 0.94 ml/min/g, p < 0.001), higher global rest MBF (1.11 ± 0.55 vs. 0.89 ± 0.19 ml/min/g, p = 0.008), and lower global MFR (2.34 ± 0.84 vs. 3.68 ± 1.04, p < 0.001) than the controls. These results were similar for the regional MFRs in the vascular-based analysis. Lower MFR correlated with more impaired left ventricular, left atrial, and right ventricular strain measures (r = -0.44, 0.38, and 0.27, respectively, all p < 0.05). Patients with HFpEF and CMD had increased risks of all-cause mortality and hospitalization compared with those without HFpEF nor CMD (adjusted hazard: 6.42, 95 % CI: 1.40-29.43, p = 0.017).

CMD by dynamic SPECT is frequently observed among patients with HFpEF and correlated with more impaired overall cardiac mechanics. HFpEF with comorbid CMD had worse clinical outcome.