Introduction
Heart failure (HF), a major public health issue, is becoming more
prevalent due to the aging and longer survival of cardiovascular
patients [1]. As HF progressing, pump failure and life-threatening
ventricular arrhythmias are major causes of death [2]. Implantable
cardioverter defibrillator (ICD) and cardiac resynchronization therapy
(CRT) are widely applied to mild or severe HF patients with reduced
ejection fraction and a wide QRS duration to reduce all-cause mortality
[3].
The COMPANION trial has demonstrated that CRT with or without ICD (CRT-D
or CRT-P) can decrease the risk of all-cause mortality and CRT-D was
associated with a lower mortality, but there is no definitive comparison
between CRT-D and CRT-P [4]. Then, plenty of observational studies
reported the various outcome of CRT-D comparing to CRT-P, and a
meta-analysis including nineteen studies presented that the addition of
an ICD is associated with a reduction in the risk of all-cause mortality
[5]. However, we cannot deny significant differences in clinical
characteristics between two groups in these studies. Patients in CRT-P
group were generally older age, more comorbidities and more frailty,
which may introduce selection bias and resulting the consequence to be
incorrect [6].
Due to lack of strong randomized evidence, it still remains
controversial whether CRT-D can bring benefits compared with CRT-P.
Current guideline of the European Society of Cardiology recommend that
the clinician should choose CRT-P or CRT-D whichever they consider
appropriate [7]. However, this choice in practice may put clinicians
in a dilemma. So far, several studies focusing on the comparison of
CRT-D and CRT-P in all-cause mortality has been reported, which used Cox
multivariate analysis or propensity score matching to minimize the
influence of clinical differences between groups[6,8-19].Therefore,
we aim to review those studies to clarify the association of all-cause
mortality and additional ICD in patients receiving CRT, and optimize the
management of patients based on characteristics.