QUEBEC, QC — A new study shows that patients who harbor preexisting right bundle branch block (RBBB) face a significantly higher risk of death 2 years after transcatheter aortic-valve replacement (TAVR)[1].
In addition, those with baseline RBBB not requiring permanent pacemaker implantation (PPI) had a 2.5-times higher risk for the composite of sudden cardiac death or need for PPI during follow-up.
“I don’t think a superior level of monitoring should be mandatory for all TAVI patients, but I can say with the data we have that this is a population at higher risk. There is no doubt about this,” senior author Dr Josep Rodés-Cabau (Quebec Heart & Lung Institute) told theheart.org | Medscape Cardiology.
“More studies need to come, but maybe with the right bundle block we need better monitoring or electrophysiology studies.”
The study was published July 19, 2017 in JACC Cardiovascular Interventions.
Although prior research has suggested higher mortality in TAVR patients with preexisting RBBB, “this area has been pooh-poohed before multiple times,” said Dr Ron Waksman (MedStar Washington Hospital Center, Washington, DC), who also penned an accompanying editorial[2].
“But what we see is that you just can’t ignore it if patients come with RBBB,” he added. “You have to be a little bit more cautious about the treatment and what could be the consequences of that treatment.”
For instance, 40.1% of patients with RBBB required PPI within 30 days of TAVR compared with 13.5% of those without RBBB.
Further, “If patients have RBBB, whether you had the pacemaker or not, you still had higher mortality,” said Waksman, who noted, however, that a recent analysis found pacemakers placed within 30 days of TAVR had no significant impact on long-term mortality.[3]
The present study included 3527 patients (50% male; mean age 82 years), of which one in 10 had RBBB on baseline ECG. Most (63%) had isolated RBBB, but 34% and 2.7% had associated left anterior and posterior fascicular blocks, respectively.
At 30 days post-TAVR, mortality was 10.2% in patients with RBBB and 6.9% in those without RBBB (P=0.024).
At a mean follow-up of 20 months, RBBB was associated with an adjusted 25% increased risk of all-cause death (hazard ratio [HR] 1.25, P=0.041) and a 38% increase in CV death (HR 1.38, P=0.018) but was not associated with sudden cardiac death (HR 0.67, P=0.50).
Use of a balloon or a self-expandable valve in RBBB patients did not alter the results.
In a subgroup analysis, patients with preexisting RBBB and without a PPI at index hospitalization discharge had the highest risk of CV death (27.8%, P=0.007). The risk for a composite of sudden cardiac death and need for PPI was also significantly higher (HR 2.51, P=0.029).
In his editorial, Waksman and coauthor Dr Arie Steinvil (MedStar Washington Hospital Center) note that the survival curves separate very early, “which supports a procedure-related causality that could be a progression of conduction defect rather than a long-term effect of RBBB with or without PPI.”
In addition, no effort was made to delineate a possible known etiology for RBBB, such as right heart or pulmonary vascular disease that may in itself enhance mortality risk.
Both Rodés-Cabau and Waksman, however, agree that use of prophylactic PPI in all patients with RBBB is the wrong message to take away from the study.
At his institution, Waksman said patients with RBBB or left bundle branch block undergo electrophysiological testing before discharge, which may slow the race to early TAVR discharge but helps to delineate who does and doesn’t need a pacemaker.
“Yes, you have one more test to go, but our rate of pacemakers is likely lower than others, and pacemakers over time can have consequences,” he said.
Rodés-Cabau said tailored monitoring will likely become part of future practice, citing the MARE trial, in which a continuous ECG monitoring device (Reveal LINQ, Medtronic) is implanted for up to 3 years in patients with a new left bundle block post-TAVR.
“We know these patients are at risk; you have a TAVR, you induce a new left bundle branch block that persists at hospital discharge, and I think we need a better way of monitoring these patients,” he said. “Maybe with the right bundle block, we will have to do similar things.”
Rodés-Cabau reported research grants from Edwards Lifesciences and Medtronic. Disclosures for the coauthors are listed in the paper. Waksman reported consulting for Abbott Vascular, Amgen, Biosensors International, Biotronik, Boston Scientific, Corindus, Lifetech Medical, Medtronic Vascular, Philips Volcano, and Symetis: speaker’s bureau participation for AstraZeneca; and grant support from Biosensors, Biotronik, Boston Scientific, Edwards Lifesciences, and Abbott Vascular. Steinvil reported no relevant financial relationships.
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