6.2. “Ablate and pace” strategy
As already mentioned, the first clinical study for HBP was by Deshmukh
et al. (2000), an observational, single-center study. In 18 patients
scheduled for AV node ablation, with narrow QRS and LVEF
<40%, with atrial fibrillation, using stylet-driven leads
without a guiding catheter, improvement in LVEF, LV dimensions, and New
York Heart Association (NYHA) Functional Classification
achieved.8 Afterwards, Occhetta et al. (2006)
conducted another small study with 16 patients, trying to achieve HBP
again using stylet-driven leads without a guiding catheter, succeeding
only in four of them HBP, while in the rest, para-Hisian pacing only
recorded. In a follow-up period of 6 months, comparing HBP to RV pacing,
the study recorded a better NYHA class, and a 6-min walk test (6MWT),
while no difference observed in LVEF and LVESV.37
Because of the difficulty in approaching the His bundle, subsequent
studies with improved leads conducted by Huang et al. (2017),
Vijayaraman et al. (2017), and Wang et al. (2019) in 42, 40, and 44
patients, respectively.38-40 In all three of these
studies, an improvement was noticed in LVEF, left ventricular
dimensions, and NYHA class compared with baseline. The authors pointed
out that AV node ablation may result in capture thresholds increase or
lead dislodgments in a minority of patients and should be taken into
account before implantation since patient safety comes first. Similar
results were shown in the study by Su et al. (2020), who applied HBP
combined with AV node ablation to 81 patients. Additionally,
pre-procedure values of high pulmonary artery systolic pressure (PASP)
≥40 mmHg, serum creatinine levels ≥97 μmol/L (≥1.1 mg/dl), or reduced
LVEF <40% pointed out as independent predictors of the
composite endpoint of all-cause mortality and heart failure
hospitalization.41 Finally, Zweerink et al. (2020)
compared HBP with AV node ablation in 44 patients, applying either
radiofrequency ablation or cryoablation. Although the results regarding
the improvement in LVEF were similar to the previous studies regarding
the ablation technique, cryoablation appeared as more procedural
time-consuming, may require more redo procedures, and does not avoid the
risk of compromising His capture thresholds.42 Be that
as it may, all studies in the “ablate and pace” indication of HBP
until now have been observational, single-center studies with few
patients and a short follow-up of a few months. Most authors of all
these studies underline the need to conduct large RCTs for this
indication, as for the previous one.