Isolated Aortic Valve Replacement in Patients with Small Aortic Annulus-A High-Risk Group on Long-Term Follow-Up

Background: Patients with small aortic annulus undergoing isolated aortic valve replacement face an often underestimated surgical risk. We describe initial clinical results and long-term follow-up of this particular high-risk group.

Methods: Between January 1998 and December 2004, 148 consecutive patients with small aortic annulus underwent isolated aortic valve replacement by implantation of a Mitroflow Aortic Pericardial Heart Valve (Sorin S.p.A., Milano, Italy) 19 or 21 mm bioprostheses. Mean age was 75.4 ± 6.2 years. Female gender, obesity, and multiple comorbidities were predominant. Mean logistic euroSCORE for mortality was 18.5 ± 2.3%. Follow-up time was 7.2 ± 2.0 years, with a total of 1066 patient years.

Results: Postoperative course and outcome during follow-up were strongly influenced by extracardiac morbidities. Hospital mortality was 6.1%, 5-year survival 71.9%, and 10-year survival 40.9%. Most patients (70.0%) died because of extracardiac reasons. Significant reasons for death were age, pre-existing atrial fibrillation, diabetes mellitus type 2, chronic renal failure, extracardiac vascular disease, history of stroke, and preoperative presentation at Canadian Cardiovascular Society class III and IV (p < 0.05). Freedom from valve-related reoperation was 99.1% at 5 years and 93.4% at 10 years. Prosthesis-patient mismatch occurred in 12.2% and was not affected with any adverse outcome (p = nonsignificant). Echocardiographic data demonstrated a significant reduction of mean transvalvular gradients in all patients (61.2 ± 19.7 mm Hg preoperatively; 18.0 ± 8.0 mm Hg during follow-up; p < 0.05). All patients reported a significant improvement in New York Heart Association functional class (p < 0.05). Conclusion: Patients with small aortic annulus are predominantly small, obese, and old-aged females with multiple comorbidities. Mitroflow valve avoids prosthesis-patient mismatch and provides excellent hemodynamics. Observed long-term results were disappointing, but they were mainly limited by extracardiac comorbidities and advanced age.