Association of Heart Rate Recovery With Microalbuminuria in Non-Obstructive Coronary Artery Disease

BACKGROUND: Non-obstructive coronary artery disease (CAD) is associated with significantly increased risk for myocardial infarction. Heart rate recovery (HRR), a measure of autonomic function, is a strong predictor of all-cause mortality. Microalbuminuria, a marker of early arterial disease, is an independent risk factor for cardiovascular disease and mortality. We aimed to investigate HRR and determine its relationship with microalbuminuria in patients with non-obstructive CAD. METHODS: We prospectively studied 565 patients who underwent elective coronary angiography. All participants underwent urinary analysis and then an exercise test. Microalbuminuria was defined as an urinary albumin-to-creatinine ratio (UACR) of 30 - 299 mg/g. The HRR was abnormal if ≤ 12 beats/min during the first minute after exercise. First, all patients were divided into two groups, patients with microalbuminuria (n = 152) and patients without microalbuminuria (n = 413). Then, all patients were re-divided into two groups, those with lower HRR (≤ 12 beats/min, n = 126) and those with higher HRR (> 12 beats/min, n = 439). RESULTS: Patients with microalbuminuria had lower HRR and patients with lower HRR had higher UACR. While UACR was negatively correlated with HRR in patients with microalbuminuria (r = -0.424; P < 0.001) and in patients with lower HRR (r = -0.192; P= 0.042), there was no correlation of UACR with HRR in neither patients with normoalbuminuria nor patients with higher HRR, respectively. In the all study population, there was a significant inverse association between UACR and HRR (r = -0.445, P < 0.001), and UACR independently predicted the presence of lower HRR (P < 0.001). CONCLUSIONS: Our findings showed that there was a significant inverse association between UACR and HRR in patients especially with microalbuminuria, and that albuminuria might predict cardiac autonomic imbalance evaluated by HRR in patients with non-obstructive CAD.