The Penn Classification System for Malperfusion in Acute Type A Dissection: A 25-Year Experience.

Background: The University of Pennsylvania classification system (Penn class) of acute type A aortic dissection (aTAAD) is used to evaluate the impact of malperfusion on surgical outcomes. The purpose of this analysis was to determine the validity of Penn class in a larger and more contemporary cohort and to compare its performance with other classification systems.
Methods: This was a retrospective study of patients who underwent aTAAD repair at our institution from 1993 to 2020. Patients were assigned to Penn class on the basis of burden of preoperative malperfusion syndrome. The association of Penn class and 30-day mortality was evaluated by multivariable regression. The discriminatory ability of Penn class for mortality was determined by a bootstrapped C statistic.
Results: There were 1192 patients, of whom 50% were assigned to Penn class A (no ischemia), 21% (253/1192) to class B (local ischemia), 14% (171/1192) to class C (generalized ischemia), and 14% (167/1192) to class B-C (combined ischemia). The incidence of mortality rose significantly with increasing Penn class from 5% (31/601) in class A to 35% (59/167) in class B-C (P < .001). After adjustment, 30-day mortality increased significantly with class B (odds ratio [OR], 2.43; 95% CI, 1.38-4.27), class C (OR, 3.39; 95% CI, 1.90-6.03), and class B-C (OR, 13.08; 95% CI, 7.90-22.15) compared with class A. The C statistic was 0.77 (95% CI, 0.72-0.80) and was significantly higher than for models featuring alternative classification systems (P < .05).
Conclusions: Penn class provides excellent discrimination for 30-day mortality after repair of aTAAD.
(Copyright © 2023 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)