Graphical Abstract.

In AF patients CRT-D upgrade reduced the risk of mortality or HF hospitalization as compared with ICD, additionally echocardiographic parameters, symptoms, and NT-proBNP levels improved. However, the risk of HF hospitalization was higher in AF patients when compared with SR. AF, atrial fibrillation or flutter; aOR, adjusted odds ratio; aHR, adjusted hazard ratio; CI, confidence interval; CRT-D, cardiac resynchronization therapy with defibrillator; ICD, implantable cardioverter defibrillator; HF, heart failure; HFrEF, heart failure with reduced ejection fraction; LVESV, left ventricular end-systolic volume; NT-proBNP, N-terminal pro b-type natriuretic peptide; PCI, percutaneous coronary intervention; PM, pacemaker; RV, right ventricular; SR, sinus rhythm.