Cardiopulmonary bypass and left ventricular systolic dysfunction impacts operative mortality differently in elderly and young patients

Abstract

Cardiac surgery is higher risk in the elderly. It has been suggested that preoperative left ventricular systolic dysfunction (LVSD) and cardiopulmonary bypass (CPB) affect elderly and young patients differently. This study investigates the predictive risk of preoperative LVSD and CPB time for operative mortality in the two groups of patients. We reviewed the data for 2616 consecutive patients aged >/=70 years and 4078 young patients who had coronary artery bypass grafting (CABG) and/or valve surgery between March 1998 and January 2007. Subgroups defined by severity of LVSD (ejection fraction >0.50 [mild], 0.31-0.50 [moderate] and </=0.30 [severe]) were analysed. Logistic regression models were constructed to identify risk factors among elderly and young patients. Elderly patients were higher risk and more often underwent valve operation. Moderate and severe LVSD were present in 22% (n=566) and 6% (n=155) of elderly compared to 18% (n=739) and 5% (n=215) of young patients (p=0.001). Operative mortality for CABG was higher in elderly patients with mild (2.3% vs 0.7%, p<0.0001), moderate (4.7% vs 2.3%, p=0.04) and severe LVSD (13.5% vs 8.8%, p=0.01). Although CPB times for similar procedures were equivalent for the two groups, procedure-specific mortality rates were higher among elderly patients for all operations. Whereas age (odds ratio [OR] 1.09, 95% confidence interval [CI] 1.03-1.15, p=0.002) and CPB time (OR 1.01, 95% CI 1.0-1.02, p<0.0001) were predictors for operative mortality for the elderly, they (age [OR 1.0, 95% CI 0.96-1.05, p=0.87], CPB time [OR 1.0, 95% CI 1.0-1.01, p=0.17]) were not for young patients. Moderate LVSD was a risk factor for young patients (OR 3.01, 95% CI 1.45-6.26, p=0.003) but not for the elderly (OR 1.33, 95% CI 0.77-2.29, p=0.30). Differences in the significance of risk factors between elderly and young patients contribute to the disproportionate operative mortalities. Our data showed that age and CPB duration increased the risk of operative mortality only in the elderly, but the impact of moderate, unlike severe, LVSD was tempered. Further studies are warranted to investigate more biocompatible bypass systems in elderly patients, and if current risk stratification should, perhaps, be revised for elderly patients.