Aortic Valve Replacement in the Moderately Elevated Risk Patient: A Population-Based Analysis of Outcomes

Abstract

As transcatheter aortic valve replacement (TAVR) therapy transitions from inoperable or high-risk patients to those considered moderate risk, a contemporary evaluation of AVR in this latter group is warranted. Using the Michigan Cardiothoracic Surgical Quality Collaborative Database, we analyzed outcomes and identified predictors of a composite end point (30-daydeath, stroke, and dialysis) for 2,979 patients (2007 to 2015) undergoing AVR (n= 1,196) or AVR and coronary artery bypass grafting (n= 1,783) with a preoperative The Society of Thoracic Surgeons predicted risk of mortality (PROM) of 4% to 8% (mean, 5.5%; interquartile range, 4.5% to 6.3%). The 30-day mortality was 3.9%. Independent predictors of death included stage 4 chronic kidney disease and the presence of pulmonary hypertension (both p< 0.05), but not year of procedure, despite a significant trend in decreased PROM during the study period (p= 0.003). Morbidity included stroke in 2.3%, and renal failure, defined as Acute Kidney Injury Network stage 1 to 3, in 43.7%, although only 5.4% required dialysis. Prolonged ventilator support was required by 21.0%. After a mean length of stay of 10 days (interquartile range 6 to 11 days), 36.4% were discharged to extended care facilities. Independent predictors of the composite outcome included the Society ofThoracic Surgeons PROM (p < 0.001 for trend) and pulmonary hypertension (p < 0.001). Compared with those presenting with pure aortic stenosis, mixed aortic stenosis and aortic insufficiency was independently protective of the composite outcome (odds ratio, 0.58; p<0.001), whereas pure aortic insufficiency was not (odds ratio, 0.87; p= 0.58). The composite end point frequency was not significantly different in the 17 hospitals developing TAVR programs (TAVR 9.6% vs non-TAVR 9.6%, p= 0.98). This population-based contemporary assessment suggests moderate-risk patients undergoing AVR experience favorable outcomes. Although increasing PROM is important in preoperative evaluation of risk, preexisting pulmonary hypertension and indication for operation are among other factors that should be considered as TAVR expands into this group of patients.