Observation ‘viable and safe’ strategy with smaller unrepaired thoracic aortic aneurysms
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Absolute risk for aortic dissection was low among a cohort of patients with thoracic aortic aneurysms as large as 6 cm, though larger size was associated with higher risk for aortic dissection and all-cause death, data show.
Professional society guideline recommendations have varied regarding changing thoracic aortic aneurysm (TAA) size thresholds for operative intervention. Additionally, the absence of definitive clinical trial evidence combined with frequent prophylactic repair in current practice limit longitudinal data available for patients with moderate and severely dilated aneurysms, Matthew D. Solomon, MD, PhD, a cardiologist and director of the Center for Thoracic Aortic Disease at The Permanente Medical Group and a physician researcher at the Kaiser Permanente Division of Research, and colleagues wrote in JAMA Cardiology.
‘Some of the best evidence to date’
“Our study provides some of the best evidence to date that observation, coupled with excellent BP control and activity restrictions, is a viable and safe strategy for nonsyndromic patients with thoracic aortic aneurysms less than 5.5 cm,” Solomon told Healio, noting that syndromic patients have certain genetic conditions that increase risk for experiencing an aortic aneurysm or dissection. “In our study, which included the largest-ever cohort of nonsyndromic thoracic aneurysm patients, we found a low risk for aortic dissection for those with aneurysms less than 5.5 cm, and a significant inflection point in risk at 6 cm.”
In a retrospective study, Solomon and colleagues analyzed data from 6,372 nonsyndromic adults with TAA identified between 2000 and 2016, as part of the Kaiser Permanente Thoracic Aortic Aneurysm cohort study. Within the cohort, 32.2% of patients were women; mean initial TAA size was 4.4 cm and 13% of patients had an initial TAA size of 5 cm or larger.
“Because many centers have been very aggressive with surgery, and long-term follow-up can be difficult, there has been a gap in our understanding about the true risk of adverse outcomes for patients with larger aortic aneurysms, particularly those greater than 5 cm,” Solomon told Healio. “Our study, which included 828 patients with aneurysms greater than 5 cm, many of whom were followed long term, helps fill this void.”
Researchers merged imaging data, including maximum TAA size, with electronic health record and comprehensive death data. Researchers estimated risks for aortic dissection, death and surgical intervention in patients with TAAs of varying sizes.
During a mean 3.7 years of follow-up, researchers found 0.7% of patients had aortic dissection, for an incidence of 0.22 events per 100 person-years.
Aortic size and dissection
Larger initial aortic size was associated with higher risk for aortic dissection and all-cause death, with an inflection point in risk at 6 cm. Estimated adjusted risks for aortic dissection within 5 years were 0.3% (95% CI, 0.3-0.7) in patients with TAA size of 4 cm to 4.4 cm, 0.6% (95% CI, 0.4-1.3) in patients with 4.5 cm to 4.9 cm, 1.5% (95% CI, 1.2-3.9) in patients with 5 cm to 5.4 cm, 3.6% (95% CI, 1.8-12.8) in patients with 5.5 cm to 5.9 cm and 10.5% (95% CI, 2.7-44.3) in patients with 6 cm or larger in time-updated models.
Rates of the composite outcome of aortic dissection and all-cause death were higher than for aortic dissection, but a similar inflection point for increased risk was observed at 6 cm, according to researchers.
“For most patients, whether syndromic or nonsyndromic, aortic size remains the most powerful predictor of dissection,” Solomon told Healio. “However, some dissections still occur at smaller aortic sizes. We need to continue to search for predictors of risk beyond aortic aneurysm size to provide our patients with true personalized risk prediction. Discovering novel genetic underpinnings for patients we have long considered ‘nonsyndromic’ will be hugely important and likely drive care for all aortic aneurysm patients in the future.”
The researchers noted that earlier prophylactic surgery should be considered “selectively” in nonsyndromic patients with TAA, “given the nontrivial risks associated with aortic surgery.”
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