Minimally Invasive Parasternal Aortic Valve Replacement: A Slow Learning Curve toward Improved Outcomes

Background: Conventional aortic valve replacement (AVR) has experienced significant changes over the past 10 years. The advent of TAVI has resulted in a decrease in numbers and a growing fraction of patients is operated using minimally-invasive accesses, mainly partial sternotomy. We adopted a parasternal, sternotomy-sparing approach in 2014 and report our total experience.

Methods: Between July 2014 and August 2018, AVR was conducted in 192 patients using a 5-cm parasternal incision. Patients were selected based on anatomic feasibility judged by preoperative CT-scan and surgeon availability. Except for porcelain aorta, or left sided aortic location, there were no exclusions. Groin cannulation was used in the majority of patients. Central cannulation was used for severe peripheral artery disease. Patients were separated into the first and second half of the entire experience and outcomes were compared.

Results: Demographic data were not statistically different between the two groups. Patients were on average 67 years old and 60% were male. BMI was 29 and mean EF was 59%. Stenosis was the main indication (85%), followed by regurgitation (15%). The cohort included patients with preoperative stroke (12%), severe COPD (11%), endocarditis (2%) and preoperative reanimation (1.5%). The EuroSCORE II was 3.37 ± 3.31 in the first and 3.68 ± 3.97 in the second half of patients (n.s.). The main implanted prosthesis type was biological (90%). Aortic annulus size (mean 24 mm) and implanted prosthesis size (mean 25 mm) was not different between groups. Operating times in the first half were just under three hours, with bypass times of 129 ± 32 min and clamp times of 77 ± 20 min. In the second half of the experience, these times changed only minimally, with stable clamp times and only 10 min reduction in bypass times. There were three conversions to sternotomy in the first, but only one in the second half. Similarly, three patients died in the first, but only one in the second half. There was a trend toward fewer complications in the second half regarding revision for bleeding (1 vs. 7.3%), stroke (4.2 vs. 0%), dialysis (3.1 vs. 1%) and pericardial effusions (3.1 vs. 1%). The O/E ratio dropped from 0.93 to 0.28.

Conclusions: Parasternal minimally-invasive AVR is a feasible technique associated with a slow learning curve but the potential to achieve improved outcomes. Considering the transcatheter alternatives, the relative risk reduction may be worth considering for future comparative trials.