Patients who survive an acute aortic dissection remain at lifelong risk for aortic aneurysm formation, aortic rupture extension, or recurrence of aortic dissection. This applies for both patients with unrepaired type B dissection and for patients with repaired type A dissection. After successful repair of acute type A dissection, patients often have persistent dissection of the distal aortic segments, anatomically equivalent to a type B dissection.

In this issue of the journal, Almeida et al. report a prospective study on midterm outcomes of 70 consecutive patients without Marfan syndrome, who underwent ascending aortic replacement for acute type A aortic dissection [1]. The aim of the investigators was to identify early predictors for aneurismal formation. Aortic aneurysm was defined as an aortic diameter ≥5.5 cm. All patients underwent a baseline evaluation by means of cardiovascular magnetic resonance (CMR) at 2 months postoperatively and thereafter three additional CMR evaluations yearly for 3 years. Using univariate analysis, increased pulse pressure, larger initial aortic dimensions, lower distensibility, and the presence of a residual flap were associated with late progression to aortic aneurysm formation. On multivariate analysis, only initial aortic diameter of the descending thoracic segment and pulse pressure were confirmed independent predictors for aneurysm formation.

The rate of distal aortic dilation and late survival after discharge from the hospital have been shown to be similar for patients with all types of aortic dissection and modes of therapy [2]. A similar rate of aortic dilation among various types of surgery can be at least partly explained by the fact that the false lumen remains commonly patent after ascending aortic surgery for type A dissection. Zierer et al. studied risk factors for aortic growth in 168 survivors of type A dissection. Aortic diameter, elevated systolic blood pressure, and presence of a patent false lumen were independent risk factors for aortic growth [3]. Song et al. found the initial false lumen diameter at the upper thoracic aortic to be the most powerful independent predictor of late aneurismal change in patients with type A or type B dissections [4]. A large false lumen probably reflects high false lumen pressure, which may play a critical role in dilating the false lumen itself and generating an aortic aneurysm. In the study of Song et al. the Marfan syndrome was also found to be an independent predictor of late aneurysm.

Aortic diameter has been recognized to be an important predictor for progressive aortic growth and aneurismal formation not only in patients with a previous aortic dissection, but also in patients without a previous event, both in patients with and without Marfan syndrome [5–7]. Indeed, also other risk factors for rapid aortic growth and aneurismal formation are largely comparable for patients with and without previous aortic root surgery and for patients with and without Marfan syndrome [8, 9].

In unoperated patients with Marfan syndrome, natural aortic growth rate and aneurismal formation have been studied in both children and adults [10–12]. Rapid aortic growth may occur in a small subset of patients and has been shown to be a risk factor for aortic dissection. Initial aortic diameter, a distensibility <3 × 10−3 mmHg in the thoracic descending aorta, previous aortic root replacement, hypertension, and aortic regurgitation have been identified as predictors for rapid aortic growth [13, 14]. In a study of 23 female patients with Marfan syndrome and 33 pregnancies, pregnancy appeared to have a small but significant influence on long-term aortic growth in women with an aortic root diameter ≥4.0 cm [15].

The onset of aortic enlargement after aortic dissection is unpredictable. Therefore, careful monitoring and regular imaging of the entire aorta is essential for optimal timing of surgery or percutaneous intervention. During the last decades, remarkable advances have been made in endovascular stent-grafting repair. Although randomized trials have not been conducted, the available data suggest that among those with vascular complication of type B dissection, early mortality is lower for stent grafting than for surgical repair [16]. Presently, it is still unknown whether prophylactic stent grafting may improve long-term outcome for uncomplicated distal aortic dissection. Identifying patients with distal dissection who may benefit from prophylactic stent grafting requires improved methods of risk stratification.

Current available data indicate that modification of surgical techniques cannot improve most factors associated with the degree of aortic enlargement. Thus, optimal long-term outcome demands lifelong radiographic follow-up. Moreover, the importance of rigorous antihypertensive medical treatment, aiming at a systolic blood pressure <120 mmHg has been stressed by several experts [3]. Beta-blocker therapy may be protective, independent of its effects on blood pressure, by reducing the impulse of left ventricular ejection [17].

Due to the advances in medical, surgical, and interventional therapy, life expectancy of patients with aortic dissection has improved substantially. Patients surviving multiple and complex re-operations or interventions have become a real challenge for aortic imaging with CMR or CT-studies [18, 19]. Lifelong and regular imaging in these patients requires involvement of trained specialists with ample imaging expertise in a tertiary referral center.