The use of intravascular ultrasound in the treatment of type B aortic dissection with thoracic endovascular aneurysm repair is associated with improved long-term survival

Objective: Intravascular ultrasound (IVUS) examination is an integral technique used for treating type B aortic dissection (TBAD) because it verifies true lumen access. The purpose of this study was to evaluate the use of IVUS, to determine factors associated with IVUS use, and to investigate the potential survival benefit associated with IVUS in the treatment of TBAD. Methods: A retrospective review of TEVARs performed for TBAD in the national Vascular Quality Initiative was performed from January 2010 to August 2018. Data collected included demographics, intraoperative and postoperative variables, and long-term mortality. Multivariable logistic regression evaluated variables associated with IVUS the use and mortality, and Cox regression was performed for adjusted survival analysis. Results: In this study of 2686 patients, the average age was 60.4 years, 69.3% were male, and IVUS examination was used in 74.6% of cases. IVUS patients were younger (60.0 years vs 61.7 years; P = .004), more often male (72.1% vs 61.3%; P < .001), exhibited less coronary disease, but had higher preoperative creatinine (1.27 +/- 0.89 mg/dL vs 1.14 +/- 0.68 mg/dL; P < .001) and were more often treated in the acute setting (55.2% vs 49.7%; P = .03). Interestingly, there were no differences in contrast use (117.4 +/- 77.6 mL vs 123.0 +/- 81.90.1 mL; P = .11) or fluoroscopy time (20.3 +/- 16.5 minutes vs 19.0 +/- 22.1 minutes; P = .10). However, IVUS cases had a greater number of devices implanted (1.84 vs 1.65; P < .001), higher rates of Zone 0 to 2 proximal seal (43.9% vs 30.7%; P < .001), higher rates of distal seal zones beyond the diaphragm (53.9% vs 37.4%; P = .001), and larger proximal and distal graft diameters, with no differences in postoperative renal function. IVUS patients notably also had higher rates of follow-up imaging (61.3% vs 54.8%; P = .003), larger maximum aortic diameters at follow-up, and more reinterventions over time. The number of aortic devices (odds ratio [OR] 1.56; 95% confidence interval [CI], 1.24-1.97; P < .001), malperfusion indication (OR, 1.68; 95% CI, 1.17-2.42; P = .005) and distal seal zone beyond the diaphragm (OR, 1.64; 95% CI, 1.30-2.07; P < .001) were independently associated with IVUS use, whereas female gender showed a trend towards less IVUS use (OR, 0.79; 95% CI, 0.62-1.01; P = .063). Even after controlling for age, preoperative comorbidities, and postoperative complications like spinal cord ischemia, IVUS was associated with a 61% decrease in the odds of mortality (OR, 0.39; 95% CI, 0.20-0.78; P = .008), with a clear survival advantage shown in adjusted survival curves. Conclusions: IVUS examination was used in the majority of TBAD, although not universally. IVUS examination was used more often in acute TBAD and more complex aortic repairs, and was independently associated with improved long-term survival. Further study is needed to understand these patterns.