Patients with conventional pacemakers or implanted defibrillators are often considered
for cardiac resynchronization therapy (CRT). Our aim was to summarize the available
evidences regarding the clinical benefits of upgrade procedures. A systematic literature
search was performed from studies published between 2006 and 2017 in order to compare
the outcome of CRT upgrade vs. de novo implantations. Outcome data on all-cause mortality,
heart failure events, New York Heart Association (NYHA) Class, QRS narrowing and echocardiographic
parameters were analysed. A total of 16 reports were analysed comprising 489,568 CRT
recipients, of whom 468,205 patients underwent de novo and 21,363 upgrade procedures.
All-cause mortality was similar after CRT upgrade compared to de novo implantations
(RR 1.19, 95% CI 0.88-1.60, p = 0.27). The risk of heart failure was also similar
in both groups (RR 0.96, 95% CI 0.70-1.32, p = 0.81). There was no significant difference
in clinical response after CRT upgrade compared to de novo implantations in terms
of improvement in left ventricular ejection fraction (DeltaEF de novo - 6.85% vs.
upgrade - 9.35%; p = 0.235), NYHA class (DeltaNYHA de novo - 0.74 vs. upgrade - 0.70;
p = 0.737) and QRS narrowing (DeltaQRS de novo - 9.6 ms vs. upgrade - 29.5 ms; p =
0.485). Our systematic review and meta-analysis of currently available studies reports
that CRT upgrade is associated with similar risk for all-cause mortality compared
to de novo resynchronization therapy. Benefits on reverse remodelling and functional
capacity improved similarly in both groups suggesting that CRT upgrade may be safely
and effectively offered in routine practice. CLINICAL TRIAL REGISTRATION: Prospero
Database-CRD42016043747.
