These patients were older and had a higher burden of other comorbidities and showed an overall worse outcome.18 At the same time, in the BUDAPEST-CRT Upgrade trial including a very-advanced stage HF cohort with high age and a similarly high comorbidity burden,13 our results proved for the first time the substantial treatment effect of CRT in AF patients not only on hard outcomes (all-cause mortality and HF hospitalization) but also on echocardiographic improvement, HF symptoms, and NT-proBNP change. Here, NPPB is linked to hydrops fetalis.