Frequent cyclic variation of heart rate is associated with left ventricular diastolic dysfunction in patients without ischemia

BACKGROUND: Cyclic variation of heart rate (CVHR) associated with sleep‐disordered breathing reflects cardiac autonomic responses to apneic/hypoxic stress. However, the association of CVHR with cardiac function is unclear. METHODS: We investigated a total of 181 patients who underwent both 24‐hour Holter electrocardiography (ECG) and quantitative gated single‐photon emission computed tomography (SPECT) myocardial functional imaging, excluding patients with atrial fibrillation, myocardial infarction, structural heart disease, and implantable devices, from January 2017 to July 2018. The number of CVHR per hour (CVHR index) in sleeping‐time Holter ECG was compared with the parameters of left ventricular (LV) systolic and diastolic functions assessed by cardiac SPECT functional imaging, peak filling rate (PFR), first‐third mean filling rate (1/3 MFR), and time to peak filling rate (TTPF). RESULTS: In all patients, the CVHR index was not associated with any parameters of cardiac functions. However, in a propensity score–matched subgroup of patients without ischemia (N = 39), the CVHR index was negatively correlated with PFR (r = −0.35, P < .05) and 1/3 MFR (r = −0.37, P < .05) but positively correlated with TTPF (r = 0.43, P < .01) and was not correlated with LV ejection fraction. Multivariate linear regression analysis revealed that high CVHR index was independently associated with LV diastolic dysfunction, even after adjusting for the relative wall thickness and LV mass index assessed by echocardiography. CONCLUSION: These results indicate that the high frequency of CVHR in sleeping time is associated with LV diastolic dysfunction in nonischemic patients, irrespective of LV geometry.