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The impact of sleep-disordered breathing on the effectiveness of cardiac resynchronization therapy

Jacek Wilczek, Danuta Loboda, Rafal Gardas, Krzysztof S. Golba

Cardiac Resynchronization Therapy (CRT) offers survival benefits to patients with Heart Failure with Reduced Ejection Fraction (HFrEF) upon optimal medical treatment. It is ensured by Left Ventricular (LV) reverse remodeling with decreased LV systolic volume, improved LV ejection fraction, decreased mitral regurgitation severity, and reduced risk of life-threatening ventricular arrhythmias. However, in approximately 30% of patients, CRT does not have the expected hemodynamic or clinical effect. For some patients, this is because of the unfavorable influence of comorbidities. The review highlights one comorbidity that may interfere with CRT’s beneficial effect: SleepDisordered Breathing (SDB). Central and obstructive sleep apnea is SDB subtypes found in nearly half of patients with HFrEF. SDB causes myocardial hypoxia and increases adrenergic activation and renin-angiotensin-aldosterone system activity. This may impair the volumetric response to CRT, inhibit the increase of the LV ejection fraction, and worsen long-term prognoses.