The association between heart rate reserve and impaired coronary flow velocity reserve: a study based on adenosine stress echocardiography.

This study was to explore the correlation between heart rate reserve (HRR) to coronary flow velocity reserve (CFVR), using adenosine stress echocardiography (SE), in patients with angina and no obstructive coronary artery disease (ANOCA). 111 ANOCA patients underwent adenosine SE were enrolled, which were divided into two groups, impaired CFVR group (CFVR < 2) and control groups (CFVR ≥ 2). The relationships between HRR and impaired CFVR were explored in total and subgroup to sex. A reduced HRR during adenosine infusion was seen in ANOCA patients with impaired CFVR (25.73 ± 8.39 vs. 34.30 ± 19.93, P < 0.001). Compared to respective controls, the blunted HRR to adenosine was more pronounced in female patients (women: 27.21 ± 8.01 vs. 39.48 ± 10.57, P < 0.001; men: 24.05 ± 8.70 vs. 29.12 ± 8.69, P = 0.041). A strong association between CFVR and a blunted HRR was observed in women (r = 0.46, P < 0.001), while no association in men (r = 0.18, P = 0.199). In female, a multivariate logistic regression identified HRR as the strongest negative predictor of impaired CFVR [HR (95% CI) = 0.854 (0.764-0.956), P = 0.006]. Based on the ROC curve, HRR < 35% was a strong indicator of impaired CFVR, with AUC of 0.838, sensitivity of 70%, and specificity of 87% in females. A blunted HRR was seen in patients with impaired CFVR, with a most pronounced effect being seen in female patients. The blunted HRR < 35% is intricately linked to impaired CFVR in women with ANOCA beyond the value of traditional risk factors, which could ultimately contribute to risk stratification of impaired CFVR in such patients.