The syndrome of angina pectoris with a normal coronary arteriogram, often termed cardiac syndrome X (CSX), is an important clinical entity, however, its causes are still unclear. Autonomic dysfunction is one of the possible causes, so we aimed to investigate the parasympathetic dysfunction assessed by heart rate recovery (HRR) and increased sympathetic activity assessed by exaggerated blood pressure (BP) response to exercise (EBPR) in CSX.Design and Method:
A total of 1393 consecutive patients without significant coronary artery disease (CAD) with anginal chest pain underwent both ergonovine provocation test and a treadmill exercise test between Jan. 2008 and Feb. 2015. Among them, the patients without significant coronary artery spasm (<70%) and positive exercise stress test with uniform ST depression ≥1 mm were enrolled as CSX. EBPR was defined as a peak exercise systolic BP ≥210 mmHg in men and ≥190 mmHg in women. HRR was defined as peak heart rate minus heart rate after a 1-minute recovery; blunted HRR was defined as ≤12 beats/min. These parameters were compared between patients with CSX and the controls.Results:
A total of 15.1% (211/1393) patients were diagnosed as CXS documented by negative ergonovine provocation test and positive exercise test (68.7% female) and 787 patients with negative ergonovine test and normal exercise test were compared as controls. HRR was significantly reduced in patients with CSX compared to the controls (27.6 ± 20.1 vs. 31.7 ± 22.9, p = 0.015) and maximal systolic BP during exercise was significantly increased in patients with CSX (176.6 ± 23.7 vs. 171.4 ± 19.9, p < 0.001). The proportion of blunted HRR (32.7% vs. 26.0%, p = 0.034) and EBBR (21.3% vs. 11.6%, p < 0.001) were significantly higher in patients with CSX than those without CSX.Conclusions:
Blunted HRR and EBBR were associated with CSX, which suggests a link between CSX and autonomic dysregulation.