This study analyzes a cohort from the prospective registry conducted by the Italian Society for Cardiac Surgery and the Italian Group of Research for Outcome in Cardiac Surgery since 1979. The analysis included the first possible or proven episode of infective endocarditis in patients aged 40–65 who required aortic valve replacement. Patients who underwent valve repair, received a homograft or autograft, underwent aortic root or ascending aorta replacement, received concurrent valve procedures, or lacked survival data were excluded. 

Out of 4365 patients operated on from 2000 to 2021, 549 (12.6%) met the criteria for analysis. Propensity score matching and a 15-year survival analysis using Cox regression were performed. The overall mechanical-to-biological prosthesis ratio was 0.95, with a significant increase in bioprostheses (p < 0.0001) over the last 5 years (mechanical-to-biological ratio of 0.73), especially in the 40–49 age subgroup. Patients who received mechanical valves were younger (median age 52 vs. 57 years; p < 0.001) and more frequently female (23.9% vs. 14.2%; p = 0.006). Patients with bioprostheses had higher rates of heart failure symptoms (21% vs. 10.4%; p = 0.001), cardiogenic shock (9.6% vs. 4.9%; p = 0.048), and preoperative orotracheal intubation (10% vs. 3%; p = 0.002). They also had higher EuroSCOREs (median 6.45 vs. 4.68; p= 0.005) and longer extracorporeal circulation (mean 90 min vs. 79 min; p = 0.004) and aortic clamping times (mean 73 min vs. 65 min; p = 0.001). Microbiological distribution was similar regardless of the prosthesis, with approximately 30% of cases having negative cultures. Early postoperative mortality was 6.2%, with similar rates in the mechanical and bioprosthesis groups (4.1% vs. 8.2%; p = 0.07; OR = 0.48; 95% CI = 0.229–1.005). For long-term prognosis, 42 (15.7%) patients in the mechanical group and 66 (23.5%) in the bioprosthesis group died. Survival rates at 1, 5, 10, and 15 years were 93.9%, 89.7%, 80.3%, and 70.1% in the mechanical group, and 87.5%, 78.2%, 63.9%, and 57.5% in the bioprosthesis group, respectively. There were two deaths (0.7%) from major bleeding in the mechanical group versus one (0.4%) in the bioprosthesis group. 

Despite including numerous variables in the propensity score analysis, the model’s area under the receiver operating characteristic curve was 0.70. Survival curves showed a sustained advantage for mechanical valves (HR = 0.55; 95% CI = 0.32–0.93). Patients with mechanical valves had a lower cumulative incidence of recurrent infective endocarditis (2.6% vs. 5%), confirmed in the adjusted analysis (HR = 0.26; 95% CI = 0.077–0.933; p = 0.039). 

COMMENTARY: 

This study aligns with previous publications, although with a longer follow-up period. Its main objective was to determine whether one type of prosthetic valve should be preferred for young patients requiring aortic valve replacement for infective endocarditis. Key findings indicate a recent trend towards bioprosthesis in this age group, with mechanical valve recipients showing better survival and a lower probability of recurrent endocarditis. No significant differences in early postoperative mortality were observed. 

Although clinical factors often guide valve choice, this decision is usually a joint one with the patient, especially in cases of infective endocarditis in patients around 60, where intraoperative findings play a crucial role. Despite the classic premise that biological materials reduce reinfection risk, this cohort’s data indicate better prognoses for patients with mechanical prostheses. However, these results may be influenced by baseline differences and residual confounding, as mechanical valve recipients were younger, predominantly female, and in better clinical condition at surgery. While propensity matching was employed, residual confounding remains likely, evidenced by the model’s area under the curve value and statistically significant prognostic differences that persisted post-matching. This residual confounding must be considered when interpreting the results. 

Unfortunately, after reviewing this and similar studies, I am still unsure which valve type I would choose if a surgeon left the decision to me. Thus, it seems that a specific criterion cannot yet be applied, differing from other causes of aortic valve disease unrelated to infective endocarditis. 

REFERENCE: 

Salsano A, Di Mauro M, Labate L, Della Corte A, Lo Presti F, De Bonis M, et al; Italian Group of Research for Outcome in Cardiac Surgery (GIROC). Survival and Recurrence of Endocarditis following Mechanical vs. Biological Aortic Valve Replacement for Endocarditis in Patients Aged 40 to 65 Years: Data from the INFECT-Registry. J Clin Med. 2023 Dec 27;13(1):153. doi: 10.3390/jcm13010153.