Low BMI emerges as long-term risk of death, stroke post-TAVI

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Low body mass index (BMI) is a primary predictor of stroke and death after transcatheter aortic valve implantation (TAVI) during long-term follow-up, whereas transapical access emerged as a predictor of kidney injury and access-site and bleeding complications in a study published online Nov. 20 in Circulation: Cardiovascular Interventions. However, the authors noted that the long-term risk of stroke or death after TAVI is low.  

“Contrary to therapeutic interventions among low-risk patients, high-risk patients with severe aortic stenosis undergoing TAVI remain at considerable risk for mortality during long-term follow-up despite elimination of a high transaortic pressure gradient” (N Engl J Med 2012;366:1686–1695), wrote the study authors. “Aside from procedural risks which are captured within established surgical risk scores, long-term survival after successful TAVI largely depends on comorbidities.”

To provide selection criteria for patients to benefit most from TAVI, they wrote it is “necessary” to identify predictors of peri-procedural risk and also potentially adverse long-term clinical outcome.

To assess these risks and outcomes, Thomas Pilgrim, MD, of the Swiss Cardiovascular Center at Bern University Hospital in Bern, Switzerland, and colleagues used time-related pathways in a multistate analysis to identify predictors of adverse long-term outcome in patients who underwent TAVI. In a cohort of 389 patients with a mean age of 82.4 years and a Society of Thoracic Surgeons Score of 6.8 undergoing TAVI between 2007 and 2011, the researchers estimated mortality and stroke, taking into account intercurrent events including kidney injury and the composite of access-site and bleeding complications.

Transapical access emerged as a predictor of kidney injury (hazard ratio [HR], 2.12) and access-site and bleeding complications (HR, 1.78), but had no impact on the risk of stroke or death.

Pilgrim et al found that BMI of 20 kg/m2 or less increased the risk of stroke or death (HR, 2.64). Patients older than 80 years (HR, 3.15), BMI of 20 kg/m2 or less (HR, 4.11), prior stroke (HR, 16.42) and a presence of atrial fibrillation at baseline (HR, 4.12) increased the risk of stroke and death after an intercurrent event of access-site and bleeding complication.

“In the present analysis, we observed a mortality rate comparable to that of the general population only in those patients undergoing TAVI who did not have any intercurrent adverse event,” the study authors wrote. “Conversely, the risk of death increased several fold after intercurrent events such as kidney injury, access-site and bleeding complications or stroke mirroring previously reported mortality rates of randomized controlled trials and registries, and corroborating the importance of peri-procedural complications on long-term prognosis.”

About the BMI findings, they wrote that low BMI may represent a marker of frailty suggestive of a pattern similar to that of the obesity paradox observed among patients undergoing PCI. In addition to being a predictor of cardiovascular death, low BMI also was independently associated with an increased risk of stroke with the majority of cerebrovascular events occurring dur­ing the peri-procedural period (53 percent in the first seven days).

In summary, Pilgrim and his colleagues said the composite of stroke or death among TAVI patients without intercurrent events is low over three years of follow-up. Despite the low frequency, they noted that low BMI is a predictor of the com­posite of stroke or death after TAVI, whereas secondary transi­tions from intercurrent access-site or bleeding complications to stroke or death are predicted by advanced age, prior stroke, low BMI and atrial fibrillation.