What Exactly Makes Age a Risk Factor for an Unfavorable Outcome after Mitral Valve Surgery?

Objective: Age has an undeniable impact on perioperative mortality. However, it is not necessarily a predictor of frailty per se, as older patients have different outcomes. To verify specific conditions underlying frailty, we examined demographics, comorbidities, frequency, and distribution of postoperative complications influencing outcomes in a challenging cohort of patients undergoing mitral valve surgery. Methods: The study enrolled 1627 patients who underwent mitral valve surgery. Patients younger than 40 years who had been diagnosed with endocarditis were excluded. Patients were divided into three groups with ages ranging from 40–59 (n = 319), 60–74 (n = 795), and >75 years (n = 513). Baseline, comorbidities, postoperative complications, and mortality were recorded. Results: The older the patients were, the more frequently they suffered from pre- and postoperative renal insufficiency (p < 0.001). The likelihood of postoperative renal failure requiring dialysis was significantly higher with pre-existing renal failure. There was a significant association between postoperative renal insufficiency and the development of postoperative pleural or pericardial effusion (p < 0.001, p = 0.016). A significant decrease in BMI was observed in patients >75 years of age compared to the 60–74 years group (27.3 vs. 28.2 kg/m(2), p = 0.007). The development of critical illnesses such as myopathy and neuropathy (CIP/CIM) was age-dependent and increased significantly with age (p = 0.04). Hospitalization duration and mortality also increased significantly with age (p = 0.013, p < 0.001). Conclusions: It appears that elderly patients with advanced renal failure have a significantly higher risk of mortality, postoperative renal failure, need for dialysis, and possibly the development of pleural and pericardial effusions in mitral valve surgery. In addition, more frequent CIP/CIM with concomitant decrease in BMI in the most advanced age group indicate sarcopenia and thus an additional feature of frailty besides renal failure.