Prognostic Role of the Modified Frailty Index in Octogenarians Undergoing Minimally Invasive Aortic Valve Replacement

Objectives: Frailty is increasingly recognized as a key determinant of surgical risk in elderly patients undergoing aortic valve replacement (AVR). This study aimed to evaluate the prognostic value of the modified Frailty Index (mFI) in a homogeneous cohort of octogenarians undergoing minimally invasive surgical AVR, to enhance risk stratification and guide surgical decision-making. Methods: We retrospectively analyzed 67 patients aged ≥ 80 years (mean 84.1 ± 3.2) who underwent isolated minimally invasive AVR. The mFI was calculated preoperatively using standardized clinical variables. Primary outcomes included 30-day mortality and perioperative complications; long-term survival was also assessed. Receiver operating characteristic (ROC) curves identified optimal mFI cut-offs. Kaplan-Meier and Cox regression analyses were used to evaluate survival and predictors of mortality. Results: The mFI demonstrated a strong prognostic accuracy. An mFI > 0.455 predicted 30-day mortality with 81.8% sensitivity and 88.4% specificity (AUC = 0.888, p < 0.001), while an mFI > 0.273 predicted perioperative complications (AUC = 0.818, p < 0.001). During a median follow-up of 51.8 ± 36.4 months, 24 patients (45.3%) died. One-year survival was 83.7%. The mFI > 0.455 was the strongest independent predictor of early mortality (HR 6.34, p = 0.001); mFI > 0.273, HFpEF with NT-proBNP > 1000 pg/mL, and chronic kidney disease were predictors of long-term mortality. Conclusions: The mFI is a simple, reproducible tool that reliably predicts early and late outcomes in very elderly patients undergoing minimally invasive AVR. Integrating frailty into preoperative evaluation may improve patient selection by prioritizing physiological over chronological age.