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Prosthetic valve endocarditis (PVE) was rare after transcatheter aortic valve replacement (TAVR) in low-risk patients, but when it did occur, the complication was associated with substantial morbidity and mortality, according to investigators from the Low Risk TAVR (LRT) study.

Incidence of PVE was 1.5% within 1 year (zero within 30 days) and 2.8% after 1 year based on an analysis of 396 low-risk TAVR recipients.

Survival was 100% in early endocarditis, but only 67% in late endocarditis, reported Giorgio Medranda, MD, of MedStar Washington Hospital Center in Washington, D.C., during the virtual meeting of the Society for Cardiovascular Angiography and Interventions (SCAI).

Of the 11 patients with PVE, the three who underwent surgical aortic valve reintervention survived. Six patients suffered embolic strokes, two of whom died after antibiotic treatment alone. These two deaths were associated with valve endocarditis, both occurring after day 500, caused by methicillin-resistant or methicillin-susceptible Staphylococcus aureus.

"Late PVE was just as frequent as early PVE but associated with increased morbidity and mortality," Medranda concluded, cautioning that these findings are no reason to favor a surgical or transcatheter valve over another during valve replacement.

The takeaway of the study is that low-risk TAVR patients are "not immune" to endocarditis, and the organisms may differ from those after surgical aortic valve replacement, commented Wael Jaber, MD, of Cleveland Clinic, who was not involved with the study.

"This first reported series of [a] low-risk population complements the data reported from trials and registries in TAVR in intermediate- and high-risk patients," Jaber said. He called the report timely given the expansion of TAVR into the low-risk population.

Medranda noted that infective endocarditis is also rare among intermediate- and high-risk TAVR patients. For these higher-risk cohorts, however, endocarditis occurs predominantly within a year of the procedure and has been associated with "much higher" in-hospital mortality (ranging from 35.6% to 47.2%) than what was observed in the present study, he added.

"Lower mortality following PVE in the LRT trials was to be expected, given the younger age and lower burden of comorbidities of low-risk patients," Medranda reasoned. "However, survival is only one hurdle for these patients, as many suffer complications of PVE, including embolic stroke."

Embolic stroke may be a greater concern for low-risk patients with PVE, as it occurred in six out of the 11 patients in this study; for comparison, these strokes are estimated to occur in 20% of intermediate- and high-risk patients with PVE.

"We hope that, since this population is at low surgical risk for re-intervention, in case they develop endocarditis post TAVR, that the surgical outcomes will be better," Jaber said. "These patients are best served by centers experienced in these complex operations and early surgical intervention could be the only cure."

The 396 patients in the study (mean age 72.9 years, mean Society of Thoracic Surgeons Predicted Risk of Mortality score 1.6%) had been pooled from the and studies, plus the LRT 1.0 bicuspid registry.

Staphylococcus and Streptococcus comprised the majority of endocarditis-causing organisms in this cohort. Those infected with the latter all survived, according to Medranda.

He acknowledged a relatively small sample and the fact that not all LRT participants had reached 2-year follow-up at the time of analysis as study limitations.

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