Stress-induced rhythm disturbances in patients with dilated cardiomyopathy

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Background. Dilated cardiomyopathy (DCM) accounts for more than 50% of all forms of cardiomyopathy and is one of the main causes of chronic heart failure, heart transplantation and the development of life-threatening arrhythmias. Some patients with DCM who do not have rhythm disturbances at rest remain at risk for their development during physical exertion. Objective. To study the structure of rhythm disturbances in patients with DCM with indications for heart transplantation and to identify predictors of the occurrence of ventricular extrasystoles (VEs) according to cardiopulmonary exercise testing (CPET). Material and methods. The study included 82 male patients with DCM who were on the waiting list for heart transplant and admitted for examination and conservative treatment aimed at compensating for heart failure. Their mean age was 45 (37;54.2) years old. All patients underwent clinical and instrumental examinations, as well as CPET with the analysis of peak oxygen consumption, anaerobic threshold level, minute ventilation volume, ventilatory equivalent for carbon dioxide, oxygen pulse, threshold load power (W), and load duration. Results. CPET conducted at baseline to patients with DCM demonstrated the presence of rhythm disturbances in the form of atrial fibrillation, VEs, and left bundle branch block in 63.4%. Newly occurring rhythm disturbances in the form of single and paired VEs were recorded in 19.5% of cases. The logistic regression analysis of echocardiography data showed that the linear size of the right atrium, the indexed parameters of the left ventricular end-systolic and enddiastolic volumes were directly correlated to VEs occurrence during CPET: OR 2.41 (95% CI [1.85–5.82], p=0.01), OR 2.26 (95% CI [1.34–7.51], p=0.03), OR 1.84 (95% CI [1.09–5.42], p=0.02), respectively.) Oxygen pulse was inversely related to VE occurrence during CPET, OR 0.52 (95% CI [0.11–0.76], p=0.02). Conclusion. The patients with DCM having indications for heart transplantation are characterized as a group of a potential risk for developing VEs during physical exertion. During CPET, newly identified single and paired VEs were registered in 19.5% of cases. The linear size of the right atrium, the indexed parameters of the end-systolic and enddiastolic volumes of the left ventricle in patients with DCM are directly related to VE occurrence during CPET. The oxygen pulse parameter is inversely related to VE occurrence during CPET.

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