Propensity score analysis of a six-year experience with minimally invasive isolated aortic valve replacement

BACKGROUND AND AIM OF THE STUDY: Although minimally invasive aortic valve replacement (MIAVR) is becoming an accepted technique, additional outcome evaluation is required. To correct for non-randomized treatment, the propensity score was used to analyze the present authors' experience with MIAVR compared to standard sternotomy (SS). METHODS: Between January 1995 and December 2002, a total of 921 consecutive patients underwent isolated AVR; 438 of these patients had MIAVR. Two matched cohorts each of 233 patients, and with comparable distributions of risk factors, were constructed using propensity analysis of prospectively collected data. Matching variables included left ventricular ejection fraction <30%, previous myocardial infarction, congestive heart failure, previous cardiac surgery, renal insufficiency, age, gender, chronic obstructive pulmonary disease (COPD), peripheral vascular disease, previous stroke or carotid disease, urgent/emergent operation, valvular pathophysiology, and atheromatous aortic disease. RESULTS: Hospital mortality and major morbidity were similar in the MIAVR and SS groups: 5.6% versus 7.3% (p = 0.45) and 13.3% versus 14.2% (p = 0.79), respectively. Multivariable analysis of all patients revealed increased mortality with severe atheromatous aortic disease (p = 0.001), COPD (p = 0.002), and urgent operation (p = 0.02). Freedom from any major perioperative morbidity was similar in both groups (86.7% versus 85.8%; p = 0.79). However, the median length of stay was shorter with MIAVR (6 versus 8 days; p <0.001). During the past three years, a greater percentage of MIAVR patients than SS patients was discharged home rather than sent to rehabilitation facilities or nursing homes (65.7% versus 52.9%; p = 0.05). CONCLUSION: MIAVR can be performed safely, with morbidity and mortality outcomes similar to those of standard sternotomy. MIAVR is associated with a decreased length of hospital stay, and a greater proportion of patients are discharged home directly.