Clinicaland Echocardiographic Impact By Temporary Cessation Of Pacing In Super-Responders Of Cardiac Resynchronization Therapy-Based On Systematic Reviews And Metaanalysis

Aims: To compare the clinical and echocardiographic parameters in cardiac resynchronization therapy(CRT)super-responders following cessation of pacing by systematically reviewing pertinent randomized controlled trials.Methods and results: An electronic search was performed using PubMed,Embase,and Cochrane Library for published studies up to 31 December 2018.Only randomized controlled trials(RCTs)were enrolled inthis analysis.Outcomes of interest included: New York Heart Association(NYHA)functional class,exercise capacity measured by6-minute walk distance(6MWD),left ventricular ejection fraction(LVEF)and left ventricular end-systolic volume(LVESV).Two RCTs characterizing 40 patients were finally incorporated.Compared with continuous pacing(on-pace),ceasing pacing(off-pace)for 6-month was associated with worsened both clinical and echocardiographic parameters,inclusive of increase in NYHA class(WMD:0.66,95%CI:0.33-1.00,P=0.0001),decrease in 6-minute walk distance(WMD:-152.41,95%CI:-234.48--70.34,P=0.0003),reduction in LVEF(WMD:-11.68%,95%CI:-16.77-6.59,P<0.00001)and increment in LVESV(WMD:23.53 ml,95%CI:-8.48-55.55,P=0.15).Innergroup comparison in off-pace group demonstrated various extent of deterioration towards the aforementioned parameters.NYHA class(WMD:0.39,95%CI:0.02-0.77,P=0.04),6-minute walk distance(WMD:-112.83 m,95%CI:-278.89-53.23,P=0.18),left ventricular ejection fraction(WMD-9.15%,95%CI-16.98--1.31,P=0.02),left ventricular end systolic volume(WMD:23.06 ml,95%CI:-9.48-55.59,P=0.16).Innergroup comparison in on-pace group didn't present complimentary amelioration in these parameters,NYHA class(WMD-0.14,95%CI:-0.47-0.18,P=0.38),6-minute walk distance(WMD:2.04 m,95%CI:-59.31-63.69,P=0.95),left ventricular ejection fraction(WMD:0.08%,95%CI:2.44-2.60,P=0.95),left ventricular end systolic volume(WMD:1.69 ml,95%CI :-8.23-11.61,P=0.74).Conclusion:In super-responders,continuous pacing is imperative to maintain the accomplished reverse remodeling,otherwise will result in deterioration.Hereby we surmise that the substantial CRT-related improvement is not appropriate to be interpreted as a halt or remission of the heart failurepathology,and all super-responders should remain the pacing activity to achieve sustained benefits.