Low Rate of Follow-up Imaging After Aortic Dissection Repair

Pauline Anderson

October 22, 2021

Adherence to guidelines pertaining to imaging after acute type A aortic dissection (ATAAD) repair is very low, a population-based study has shown.

Only 14% of patients had guideline-recommended imaging over their follow-up period.

Dr Jennifer Chung

Among factors possibly contributing to this "extremely poor" adherence rate is the lack of clarity over who is in charge of the patient following surgery, study author Jennifer Chung, MD, cardiovascular surgeon, Munk Cardiac Centre, and assistant professor of surgery, University of Toronto, Canada told Medscape Medical News. She reminds clinicians that "patients who suffer dissections do require imaging, and if you're unable to follow these patients regularly then you should refer them."

In patients who survived the initial 3 months after ATAAD repair, mortality was 29%, and aortic reintervention rates were 17% at 10 years, the researchers found.

The study was presented at the annual meeting of the Canadian Cardiovascular Society and was published online today in the Journal of the American College of Cardiology (JACC).

ATAAD, a life-threatening tear in the most proximal part of the aorta, is generally managed with surgery. But survivors of the repair are prone to long-term complications such as residual dissections or aneurysms, so long-term imaging surveillance is needed, said Chung.

"Aneurysm disease tends to be silent until it's not," she said. "From our perspective as aortic surgeons, it's good to know about changes over time so we can intervene on them electively rather than emergently."

The American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend imaging follow-up at 1, 3, 6, and 12 months, post-dissection and, if stable, annually thereafter.

The study included 888 patients in Ontario, Canada, who underwent urgent or emergent repair of an ATAAD from 2005 to 2018 and survived for at least 3 months. The median age of the cohort was 61 years; 70% were male and 87.5% lived in an urban area. The median follow up was 5.2 years.

Researchers tapped into various linked databases for information on ATAAD repair, subsequent imaging, aortic reintervention, and mortality as well as demographics and, if applicable, deaths.

The guideline-directed imaging schedule was defined as a 6-month and 12-month scan followed by an annual scan.

Overall, 14% of patients had these scans throughout follow-up. The rate dropped off quickly over time, to 21% at 2 years and to less than 2% at 8 years.

The low rate of imaging surveillance "was striking" and "compares starkly" to the 80% rate at 2 years in a similarly conducted study of imaging follow-up after endovascular infrarenal abdominal aortic aneurysm repair (EVAR) in Ontario, said the authors.

A number of factors could contribute to low adherence to imaging recommendations for ATAAD patients, they speculate. Surgeries may be carried out at centers far from the patient's home, which may contribute to loss of follow-up.

After surviving the operation, patients return home and "become kind of orphan patients where nobody really knows who's responsible" for them, said Chung.

Imaging may also vary depending on whether the patient is followed by a general practitioner, cardiologist, vascular surgeon, or cardiac surgeon.

"This population does not necessarily have someone in charge of them," said Chung. "Patients can't be falling through the cracks."

There has been increased interest in a "team-based" approach to aortic disease at dedicated centers "with the expertise to actually follow these patients," said Chung.

But the "blanket" guideline recommendation that all patients be imaged on a strict schedule may be too broad and resource-intensive, she said. "In my opinion, this is a definite glaring hole in the guidelines, and a lot of work could be done to refine it."

Changes might include tailoring recommendations to individual patients. "Some patients are going to be at way lower risk of a future event than others," said Chung.

As for mortality outcome, the study showed the overall rate was 4% at 1 year, 14% at 5 years and 29% at 10 years. Risk factors for mortality included increased age, chronic kidney disease, and the lowest quintile of neighborhood income.

Female gender was a protective factor for overall long-term mortality. "Our study shows if women do survive these surgeries, they do better in the long-term," said Chung, adding it's unclear why this might be.

The cumulative incidence of aortic reintervention, considering death a competing risk, was 3% at 1 year, 9% at 5 years and 17% at 10 years. The 10-year rate is "on the lower end" compared with previous smaller, single-center studies, where rates ranged from 16% to 28% at 10 years, noted the authors.

At the latest follow-up, 11% of aortic reinterventions were performed: the majority (68%) were urgent and 32% were elective. The mortality rate within 30 days of any aortic reintervention was 9%.

Reintervention or death for the entire cohort was 6% at 1 year, 21% at 5 years and 39% at 10 years.

As this was an administrative database, specific anatomic characteristics of the type A dissection, such as the presence of residual dissection, were unavailable, the authors note. Other limitations were that the cause of death and individual surgeon-level data were not captured.

In an accompanying editorial, Jean Bismuth, MD, Houston Methodist DeBakey Heart & Vascular Center, Houston, Texas, and colleagues said the article "presents a valid argument that, in real life, strict follow-up protocols are not adhered to."

"Guidelines are based on low levels of evidence and newer imaging technologies are not implemented," they write.

A possible solution to circumvent this "gap in knowledge and meet actual patient needs" is to stratify patients according to aortic indicators, for example presence of aortic diameter >40 mm or connective tissue disorders, and tailor their imaging follow-up according to their needs, the editorialists note.

Although the authors of the study don't describe operative technique, "other studies have failed to identify differences in long-term survival between surgical strategies," these authors noted.

They pointed out that although gender was a protective factor for mortality in this study, another recent report showed women had a higher in-hospital mortality rate but no significant sex differences in mortality at 5 years.

"More gender-specific studies are essential to understand TAAD natural history in women," they conclude.

This study was supported by the Cardiovascular Surgery Division at the Toronto General Hospital.

Canadian Cardiovascular Conference 2021. Presented October 22, 2021.
J Am Coll Cardiol. Published online October 22, 2021. Abstract, Editorial

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