Background and aim of the study: Structural valve deterioration (SVD) is the most common cause of bioprosthetic valve failure. Coronary disease risk factors, including hypercholesterolemia, might predict SVD. Here, the relationship was examined between preoperative cholesterol levels and SVD in patients undergoing bioprosthetic aortic valve replacement (AVR).
Methods: A total of 7,150 patients (mean age 68 +/- 12 years) was identified who underwent bioprosthetic AVR at the Cleveland Clinic Foundation, between January 1975 and December 2002. Preoperative and postoperative variables were retrieved from a prospective, computerized database. A parametric method was used to estimate the distribution of valve explants; a multivariable risk factor model was then developed to include patient demographics, cardiac and non-cardiac comorbidities, valve type and interactions. The primary end-point was explant for SVD. All explants were examined, and observations were censored at the time of any explant or death. Bootstrap analysis was used to validate the model.
Results: Among 7,150 patients, 208 had explants for SVD. Mean preoperative total cholesterol (TC) was 203 +/- 48 mg/dl, HDL-cholesterol 45 +/- 15 mg/dl, and LDL-cholesterol 121 +/- 41 mg/dl. The average follow up was 3.7 years, and 1,169 patients (16%) were followed for more than eight years. In multivariable analysis, only younger age (p < 0.0001), greater body weight (p < 0.0001), elevated serum creatinine level (p = 0.0004) and use of a pericardial valve (p = 0.04) predicted SVD. Neither preoperative cholesterol nor its fractions predicted valve explant for SVD (log-rank p = 0.19) Moreover, no cardiovascular risk factors were predictive of SVD.
Conclusion: Preoperative cholesterol levels do not predict SVD in patients undergoing bioprosthetic AVR. Whether long-term hypercholesterolemia or statin therapy impacts SVD requires further investigation.