• High False Lumen Systolic Antegrade Flow and Significant Diastolic Retrograde Flow Raise Risk in Aortic Dissection Patients

    High systolic antegrade flow volume in the false lumen (FL) of acute aortic dissection patients, as well as significant diastolic retrograde flow, leads to higher risk of complications in need of more aggressive management, according to a new prospective study published Monday online.

     

    Advancements in surgical and medical treatment of the otherwise lethal condition known as aortic dissection (AD) has led to increasing – but still widely varied – survival rates of between 48% to 82% at 5 years, and 43% to 66% at 10 years, the researchers, led by Arturo Evangelista, MD, PhD, from Universitat Autonoma de Barcelona, Spain, noted.

     

    This has led to an increasing healthcare burden because of high demand for specialized care, lifelong follow-up and repeat interventions, expert commentators noted in an accompanying editorial. In particular, persistent patent FL in the descending aorta after the acute phase is common in type A and B dissections, and is strongly associated with higher risk of repeat surgery and mortality, the researchers added.

     

    “Prediction of late events is highly desirable, as it would allow preventive endovascular repair, which comes with its own procedural cost and risk, to be targeted to a high-risk population,” Nicholas S. Burris, MD, of the University of Michigan, and fellow editorialists said.

     

    The current study – published ahead of the June 21 issue of the Journal of the American College of Cardiology – therefore set out to assess the natural evolution of noncomplicated AD and ascertain (by magnetic resonance imaging [MRI]) whether different FL flow patterns have independent prognostic value for AD-related events beyond established morphologic parameters.

     

    The study enrolled 131 consecutive patients, 78 with surgically treated type A dissections and 53 with medically treated type B dissections, from January 2000 to December 2015 and followed them prospectively after acute AD with persistent patent FL in the descending aorta.

     

    At baseline, the patients’ mean age was 60.3 years (similar across the type A and B dissection type groups), 74% were male (76.9% vs. 69.8%, respectively), and hypertension was present in 77.1% overall (70.6% vs. 86.8%, respectively). Those older than 80 years, with a total FL thrombosis of the AD, maximum aortic diameter of 5 mm or more, moderate to severe aortic regurgitation and severe comorbidities were excluded.

     

    Dyslipidemia was present was present for 25.8% (22.4% of type A vs. 32.3% of type B), 10.6% were diabetic (11.5% vs. 9.4%, respectively), 13% had atherosclerosis (11.5% vs. 15.1%) and 21.4% had chronic obstructive pulmonary disorder (17.9% vs. 26.4%).

     

    Maximum aortic diameter, true lumen compression, entry tear and partial FL thrombosis were assessed by computed tomography (CT), while systolic antegrade true lumen and FL flow volumes, and diastolic antegrade and retrograde flows, were analyzed by MRI in the first year post-AD.

     

    No differences were found in clinical and imaging characteristics between the two groups, except for entry tear area and basal descending aortic diameter, which were larger in patients with type B AD (P = 0.003 and P = 0.048, respectively).

     

    After a median follow-up period of 8 years, 43 patients (32.8%) had aorta-related events, 25 (19.1%) of whom died (17 from sudden death and eight in the post-operative phase of surgery of thoracic endovascular aortic repair procedures), and 18 (13.7%) of whom required surgical or endovascular treatment because of severe descending thoracic aortic dilation or redissection.

     

    Survival free from sudden death and surgical or endovascular treatment for the total population at 5 and 10 years were 0.86 (95% confidence interval [CI]: 0.78-0.91) and 0.58 (95% CI: 0.47-0.68), respectively. No significant differences were found between type A and type B cases (P = 0.325).

     

     

     

    FL systolic antegrade flow of 30% or more with respect to total systolic antegrade flow, and retrograde diastolic flow of 80% or more with respect to total diastolic FL flow, were both predictors of aortic events.

     

    In multivariate analysis, baseline descending aortic diameter of 45 mm or more (hazard ratio [HR]: 2.67; 95% CI: 1.38-5.19; P = 0.004), type B AD (HR: 2.26; 95% CI: 1.13-4.51; P = 0.021), and MRI flow pattern III (HR: 33.46; 95% CI: 7.82-143.15; P < 0.001) – defined by high entry flow with high reversal diastolic flow – were all independent predictors of AD-related events.

     

    “High antegrade systolic blood flow volume accompanied by retrograde diastolic flow in the FL near the distal AD flap, as assessed by MRI, identifies patients at high risk for complications and progressive aortic enlargement,” the researchers concluded.

     

    They added that: “The long-term outcomes of AD with patent FL are heterogeneous in patients free of clinical complications and severe comorbidities. FL flow assessed by MRI is a better predictor of aortic events than morphologic parameters alone.

     

    “The presence of high systolic antegrade flow in the FL with significant diastolic retrograde flow identifies the subgroup of patients with a higher risk for complications, regardless of dissection type, in whom more aggressive management would be indicated.”

     

    The researchers went on to call for prospective studies to validate the reliability and clinical utility of FL flow measurements, including the subacute phase.

     

    Burris and his fellow editorialists said the results strengthen a “growing body of literature on the importance of MRI flow imaging for the identification of high-risk patients.” A subset of patients with AD with a pressurized FL and insufficient outflow can be identified with conventional MRI sequences and “may benefit most from earlier/prophylactic aortic repair,” they added.

     

    “Considering the shortcomings of current therapies for patients with chronic AD, this work emphasizes the importance of new avenues of research into individualized, hemodynamically targeted treatment strategies.

     

    “Although anatomic features have taught us much about AD, MRI blood flow imaging is a tool well positioned to untangle the complexity and heterogeneity of this disease, which has thus far confounded reliable risk predictions.”

     

    Sources:

     

    Evangelista A, Pineda V, Guala A, et al. False Lumen Flow Assessment by Magnetic Resonance Imaging and Long-Term Outcomes in Uncomplicated Aortic Dissection. J Am Coll Cardiol 2022;79:2415-2427.

     

    Burris NS, Fleischmann D, Hope MD. Blood Flow Patterns of Risk in Aortic Dissection: Time to Go With the Flow? J Am Coll Cardiol 2022;79:2428-2430.

    Image Credit: barks – stock.adobe.com

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