Effects of prosthetic heart valve-associated subclinical intravascular hemolysis on endothelium and cardiovascular system: a retrospective cohort study

Background Mechanical prosthetic heart valve implantation is a surgical treatment method used in the treatment of severe and symptomatic valvular disease. Regular follow-up of prosthetic valve functions, clinical and laboratory parameters is of great importance in patients who have undergone valve implantation. Chronic subclinical intravascular hemolysis is frequently seen in this patient group, but its management and long-term adverse effects are uncertain. In this study, it was aimed to determine the effects of subclinical hemolysis on the endothelium by comparing the frequency of clinical events such as pulmonary hypertension and atherosclerotic vascular events in patients with mechanical valves. Methods In this single-center, retrospective cohort, patients with functional mechanical prosthetic valves were evaluated. A total of 346 patients who underwent aortic and/or mitral valve replacement were included in the study according to the inclusion and exclusion criteria. The severity of mechanical intravascular hemolysis (MIH) in patients was evaluated based on serum lactate dehydrogenase (LDH) levels measured during follow-up after valve implantation. The study population was divided into two groups according to the median follow-up LDH value (fLDH) of 264.5 U/L: non-hemolysis/mild hemolysis (Group 1) and moderate hemolysis (Group 2). Study patients were evaluated for pulmonary hypertension (PHT) and major adverse cardiovascular events (MACE) during the retrospective follow-up period. Results The mean age of the study patients was 57.5±12.5 years, and the study population consisted of 65% male patients. The mean follow-up period of the patients was 9.4 years (±3.3). MACE (composite of non-fatal cerebrovascular event, myocardial infarction, new-onset arrhythmia, cardiovascular death, and elective coronary revascularization) were observed in 5.2% (n=18) of the study population. New-onset PHT was detected in 122 patients (35.3%) during follow-up period. When compared in terms of MACE, 1 event (0,6%) occurred in group 1, while 17 events (9,8%) occurred in group 2 (p<0.001). In the multivariate analysis performed with logistic regression method to determine statistical significance of the parameters that stand out in terms of MACE prediction, fLDH value ≥ 265 and having DM were found to be statistically significant variables (fLDH; OR = 37.18, 95% CI: 3.24-426.35, p=0.004, DM; OR = 27.14, 95% CI: 1.22-601.72, p=0.037). Conclusion The results of the study show that subclinical intravascular hemolysis in prosthetic heart valve patients may be associated with the development of MACE and PHT. Evaluation of the severity of hemolysis, which can be evaluated by LDH level in routine clinical practice, can be a prognostic factor in this patient group and may contribute to the appropriate management and treatment of patients. Baseline characteristics Critical outcomes of study