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Surgical or transcatheter aortic valve replacement (TAVR) rarely resulted in prosthetic valve endocarditis in the PARTNER trials of high- and intermediate-risk patients, investigators found.

This form of infective endocarditis was equally unlikely to turn up after TAVR as after surgical aortic valve replacement (SAVR; 5.21 vs 4.10 per 1,000 person-years, P=0.44), even after adjusting for the competing risk of death.

When it did occur, prosthetic valve endocarditis was strongly associated with all-cause mortality (HR 4.42, 95% CI 3.42-5.72), according to Wael Jaber, MD, of the Cleveland Clinic, and colleagues.

The timing of the infection, typically more than 30 days afterward, was similar between TAVR and SAVR groups, Jaber's group reported in a paper published online in .

Their data had come from PARTNER trials and registries where definite prosthetic valve endocarditis was adjudicated by a clinical events committee. In total, there were 8,530 people with severe aortic stenosis who received TAVR or SAVR. Average follow-up had lasted 2.69 years.

It was "reassuring" to see these "very low" reported rates of endocarditis, commented Brian Lindman, MD, of Vanderbilt University Medical Center in Nashville, Tennessee.

"While perhaps somewhat unexpected, the rates of endocarditis are similar between TAVR and SAVR, despite the differences in how the valves are delivered – surgical valves are delivered into an open chest in a more sterile operating room versus a transcatheter valve which is often delivered percutaneously in a less rigorously sterile cath lab," he told 名媛直播.

The investigators observed no difference in prosthetic valve endocarditis rates between transfemoral and alternative access sites for catheterization or standard surgical access patients in their study.

Staphylococcus was responsible for significantly more infections after SAVR than TAVR (58.3% vs 28.4%, P=0.04), whereas streptococcal endocarditis was numerically more common after TAVR (28.4% vs 8.3%, P=0.14).

"Although enterococcus was the third most frequent organism involved, there was no difference in infection rates between TAVR and SAVR. This is important because of the prior postulation that enterococcus, a genitourinary and groin pathogen, may implicate transfemoral access and thus make TAVR inherently at higher risk for PVE [prosthetic valve endocarditis] than SAVR," according to Jaber and colleagues.

The overall prosthetic valve endocarditis rate of 5.06 events per 1,000 person-years confirmed the infrequent occurrence of these infections in contemporary practice, they said.

"The widespread adoption of TAVR and application to lower-risk patients makes understanding mechanisms of valve failure increasingly important," the authors concluded. "We herein demonstrate in the largest trials and registries of TAVR that PVE remains rare, but often fatal, in modern AVR experience and that there is no difference in incidence, predictors, or risk of PVE between TAVR and SAVR."

On multivariable analysis, the baseline predictors of prosthetic valve endocarditis were:

• Cirrhosis: incident RR 2.86 (95% CI 1.33-6.16)
• Pulmonary disease: incident RR 1.70 (95% CI 1.16-2.48)
• Renal insufficiency: incident RR 1.71 (95% CI 1.03-2.83)

These predisposing factors can't really be modified to reduce the risk of endocarditis, Lindman noted.

"Unlike prior studies, we did not see associations with age, sex, diabetes mellitus, aortic insufficiency, or orotracheal intubation. The patient population in this study was older than previous studies, and most of the procedures occurred in the operating room with general anesthesia. These factors may account for the differences observed," Jaber's team noted.

The study was subject to the limitations of the diagnostic criteria for definite prosthetic valve endocarditis, they added.

"Favoring specificity over sensitivity to identify and study the most serious and definitive forms of PVE, it is important to note that prior pathological studies of confirmed PVE showed the definite PVE criteria to have only been met in 76-89% of patients, thus we may be slightly underestimating the true incidence of infections," the authors acknowledged.

Moreover, the competing risk analysis that was used to control for potential alternative causes of death in high-risk patients did not exclude the possibility of unmeasured confounding.

"As such, it is unclear whether the dominant factors leading to PVE in higher risk patients with less inherent longevity to experience a PVE event are similar to those when TAVR is applied to lower risk patients with more post-TAVR lifetime risk to experience PVE," Jaber and colleagues said.

Lindman also noted that the study population did not undergo minimalist TAVR, a less invasive approach that might reduce the risk of endocarditis.

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