Control BP and Pain in Type B Aortic Dissection

Abstract & Commentary

By Andrew J. Boyle, MBBS, PhD

Source: Trimarchi S, et al. Importance of refractory pain and hypertension in acute type B aortic dissection. Insights from the International Registry of Acute Aortic Dissection (IRAD). Circulation. 2010;122:1283-1289.

Indications for surgical or interventional management in acute type B aortic dissection (ABAD) include malperfusion syndromes, progression of dissection, and aneurysm expansion. The prognostic significance of refractory pain and high blood pressure (BP) are not completely understood. Accordingly, Trimarchi and colleagues examined the IRAD database to determine the effects of ongoing pain and incomplete blood pressure control on in-hospital outcomes.

The IRAD registry is an international multi-center registry of patients presenting with acute aortic dissection. This study presents data on patients presenting between 1996 and 2004 with ABAD. They included patients with ABAD and patients with intramural hematoma. ABAD was defined as an aortic dissection involving the descending aorta with no tear in the ascending aorta or arch, and intramural hematoma was defined as a regionally thickened aortic wall with no double lumen or entry flap. The patients were separated into group 1 (intermediate risk) with recurrent or refractory pain and/or refractory hypertension but no other clinical complications; group 2 (low risk) with no refractory pain or hypertension and no other clinical complications; and group 3 (high risk) with one or more of the following complications: shock, peri-aortic hematoma, spinal cord ischemia, pre-operative mesenteric ischemia/infarction, acute renal failure, or limb ischemia. Group 3 were excluded from this analysis, as they were considered to have indications for surgery and analysis was confined to the 365 patients in groups 1 and 2.

The mean age of patients was 63.5 years, 5% had diabetes and 33% were female. Intramural hematoma was present in 11.4%. Baseline characteristics were well matched between groups, except for a higher prevalence of Marfan's syndrome in group 1 (7.3% vs. 2.1%, p = 0.03), as well as higher rates of abrupt pain onset (92.2% vs. 81.3%, p = 0.03), migrating pain (35.5% vs. 16.6%, p = 0.0008), and radiating pain (51.6% vs. 33.6%, p = 0.007). Patients in group 1 (n = 69) were more likely to undergo surgical (36.2% vs. 8.4%, p < 0.001) or endovascular therapy (39.1% vs. 3.7%, p < 0.001) than patients in group 2 (n = 296). There was longer time to invasive treatment in group 1 than in group 2 (240 hrs vs. 99 hrs, p < 0.01). Overall in-hospital mortality in patients with recurrent/refractory pain or refractory hypertension (group 1) was higher than in those without (group 2) [17.4% vs. 4.0%, p < 0.001]. In those managed medically, group 1 also had a higher mortality (35.6% vs. 1.5%, p < 0.001). Multivariable analysis showed that refractory/recurrent pain or refractory hypertension are associated with higher risk of in-hospital mortality (odds ratio 3.3, p = 0.04), as are age > 70 years (OR 5.1, p < 0.01) and absence of chest pain (OR 3.5, p = 0.05). The authors conclude that in uncomplicated ABAD patients, medical therapy was associated with excellent in-hospital outcomes. By contrast, the presence of recurrent pain and/or refractory hypertension was associated with increased in-hospital mortality, particularly in those patients managed medically. These observations suggest that aortic interventions, such as by an endovascular approach, may be indicated in this intermediate-risk group.

Commentary

Type B aortic dissections traditionally have been managed medically, as advised in the ACC/AHA guidelines, with surgery or endovascular therapy being reserved for cases of impending aortic rupture or side-branch compromise. The current study reinforces the importance of strict BP and pain control in patients managed medically. Although this is a retrospective, observational study, rather than a prospective, randomized trial, it appears that inadequate pain or BP control is associated with higher in-hospital mortality, especially in the patients managed medically. Whether these patients should undergo more invasive therapy remains unknown, and the authors' conclusion that an endovascular approach may be warranted is probably somewhat overzealous. With the rapid evolution of endovascular therapies and the variation in regional practice patterns and experience with these technologies, it is difficult to make any conclusions from this data set. Furthermore, the equipment used in 1996 is already obsolete, and endovascular therapy was only used in the minority (38 patients; 10.4% of the cohort). Thus, the most appropriate conclusion from this study is to underscore the importance of strict BP and pain control in patients with acute type B aortic dissection.