Why the study?
De novo CRT is recommended in mild HF with LVEF <50% and AVB, but CRT upgrade from RVP has been limited to severe HF with LVEF <=35% and AVB.
Does CRT upgrade from right ventricular pacing improve clinical outcomes and left ventricular reverse remodeling compared to de novo CRT in mild heart failure patients with atrioventricular block?
Does CRT upgrade from right ventricular pacing improve clinical outcomes and left ventricular reverse remodeling compared to de novo CRT in mild heart failure patients with atrioventricular block?
In mild heart failure patients with AV block, upgrading to CRT from right ventricular pacing yields equivalent mid-term clinical outcomes and superior left ventricular reverse remodeling compared to de novo CRT implantation.
CRT upgrade may support LV remodeling in mild HF with AVB; leaves open whether outcomes justify expanded indications.
BACKGROUND: Indication for de novo cardiac resynchronization therapy (CRT) has been recommended in mild heart failure (HF) patients with left ventricular (LV) ejection fraction (LVEF) <50% and atrioventricular block (AVB). In contrast, the indication of CRT upgrade from right ventricular pacing (RVP) has been limited to severe HF patients with LVEF≤35% and AVB. This study examined LV volumetric responses and clinical outcomes in mild HF patients with AVB who underwent CRT upgrade, compared with those of de novo CRT patients. METHODS: This retrospective study focused on patients with CRT due to AVB, mild HF at New York Heart Association class II and LVEF<50%. A total of 58 patients were divided into two groups: (1) 27 patients with CRT upgrade from RVP>40% (Upgrade group, UG), and (2) 31 patients with de novo CRT implantation (De novo group, DG). The echocardiographic assessment was performed at baseline and six months after CRT. The study endpoint was a combined endpoint with total mortality, HF hospitalization, or ventricular tachyarrhythmia events. RESULTS: At six months after CRT, the LV end-systolic volume (LVESV) was significantly reduced in both groups (from 144.3±39.4 mL to 111.1±33.5 mL in UG, p<0.01; from 134.5±36.6 mL to 123.5±45.6 mL in DG, p<0.05); however, a significant improvement in LVEF was obtained in UG but not in DG (from 31.7±6.8% to 39.7±8.5% in UG, p<0.01; from 34.2±7.3% to 36.0±9.7% in DG, p=0.15). Consequently, the changes in LVESV and LVEF were significantly greater in UG than in DG. During the follow-up of 989 days, the survival rate for the composite events were similar between both groups (p=0.18). CONCLUSIONS: LV reverse remodeling was significantly greater in UG than DG, and the incidence of clinical composite events at mid-term follow-up was equivalent between UG and DG. CRT upgrade could be an acceptable indication in mild HF patients dependent on RVP.
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Kanai et al. (2021) studied this question.
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