Abstract
OBJECTIVE: With the recent expansion of the Centers for Medicare and Medicaid Services (CMS) coverage, transfemoral carotid artery stenting (tfCAS) is expected to play a larger role in the management of carotid disease. Existing research on the tfCAS learning curve, primarily conducted over a decade ago, may not adequately describe the current effect of physician experience on outcomes. Since about 30% of perioperative stroke/death post-CAS occur after discharge, appropriate thresholds for in-hospital event rates have been suggested to be <4% for symptomatic and <2% for asymptomatic patients. This study evaluates the tfCAS learning curve using Vascular Quality Initiative (VQI) data.
METHODS: We identified VQI patients undergoing tfCAS between 2005 and 2023. Each physician's procedures were chronologically grouped into 12 categories, from procedure counts 1-25 to 351+. Primary outcome was in-hospital stroke/death rate; secondary outcomes were in-hospital stroke/death/MI, 30-day mortality, in-hospital stroke/transient ischemic attack (stroke/TIA), and access site complications. The relationship between outcomes and procedure counts was analyzed using Cochran-Armitage test and a generalized linear model with restricted cubic splines. Our results were then validated using a generalized estimating equations model to account for the variability between physicians.
RESULTS: We analyzed 43,147 procedures by 2,476 physicians. In symptomatic patients, there was a decrease in rates of in-hospital stroke/death (procedure counts 1-25 to 351+: 5.2% to 1.7%), in-hospital stroke/death/MI (5.8% to 1.7%), 30-day mortality (4.6% to 2.8%), in-hospital stroke/TIA (5.0% to 1.1%), and access site complications (4.1% to 1.1%) as physician experience increased (all p-values<0.05). The in-hospital stroke/death rate remained above 4% until 235 procedures. Similarly, in asymptomatic patients, there was a decrease in rates of in-hospital stroke/death (2.1% to 1.6%), in-hospital stroke/death/MI (2.6% to 1.6%), 30-day mortality (1.7% to 0.4%), and in-hospital stroke/TIA (2.8% to 1.6%) with increasing physician experience (all p-values<0.05). The in-hospital stroke/death rate remained above 2% until 13 procedures.
CONCLUSIONS: In-hospital stroke/death and 30-day mortality rates after tfCAS decreased with increasing physician experience, showing a lengthy learning curve consistent with previous reports. Given that physicians' early cases may not be included in the VQI, the learning curve was likely underestimated. Nevertheless, a substantially high rate of in-hospital stroke/death was found in physicians' first 25 procedures. With the recent CMS coverage expansion for tfCAS, a significant number of physicians would enter the early stage of the learning curve, potentially leading to increased post-operative complications.