Study Explores Predictors, Consequences of Stroke After TAVR

Among patients undergoing transcatheter aortic valve replacement (TAVR), the etiology behind cerebrovascular events depends on the timing, with earlier events mainly connected to procedural factors and later events tied to patient comorbidities. The findings, from a large observational study published online November 13, 2012, ahead of print in Circulation, suggest that clinicians may be able to take preventative measures against stroke and transient ischemic attack (TIA).

Investigators led by Josep Rodés-Cabau, MD, of Laval University (Quebec City, Canada), looked at 1,061 consecutive patients who underwent TAVR at 5 centers between January 2005 and September 2011. Valve Academic Research Consortium-defined cerebrovascular events that occurred over a median follow-up of 12 months (range, 3-23 months) were categorized according to timing as:

• Acute: up to 24 hours
• Subacute: 1 to 30 days
• Late: beyond 30 days

Most patients were treated via transfemoral access (68.4%). Balloon-expanding valves were used in 64% of cases and self-expanding valves in 36%.

Predictors Vary by Timing

Fifty-four patients (5.1%) experienced a cerebrovascular event within 30 days of TAVR, including 30 major strokes (2.8%) and 15 minor strokes (1.4%) plus 9 TIAs (0.8%). Approximately half were acute (54%) and half subacute (46%). All but 2 of the strokes were ischemic.

Beyond 30 days after TAVR, late events occurred in another 35 patients (3.3%), of whom 22 experienced stroke (16 ischemic, 6 hemorrhagic) and 13 TIA.

On multivariable analysis, independent predictors of cerebrovascular events varied according to timing (tables 1 and 2).

Table 1. Predictors of Acute and Subacute Cerebrovascular Events     

Table 2. Predictors of Late Cerebrovascular Events

Major stroke at 30 days was associated with increased mortality, both early (OR 7.43; 95% CI 2.45-22.53) and late (HR 1.75; 95% CI 1.01-3.04).

Room for Improvement

According to the paper, the results raise the possibility of preventative measures.

“Balloon postdilation increases the interaction between the stent frame of the valve prosthesis and the native aortic valve, which might indeed favor the dislodgment of calcific particles from the native valve,” the investigators note. As such, postdilation should be limited to patients with more significant levels of paravalvular leakage, they say, adding that appropriate assessment of the aortic annulus to avoid valve undersizing and, in the future, development of devices that minimize paravalvular leak are both important. Embolic protection devices may also prove useful.

In terms of subacute events, the risk associated with new-onset A-fib suggests “that improvements in both the prevention of atrial arrhythmias and antithrombotic treatment following the procedures should play a role in the reduction of 30-day [cerebrovascular events after TAVR],” Dr. Rodés-Cabau and colleagues write.

However, little can be done to prevent late events, they note, since their predictors “reflect . . . the background risks of this population and make it highly unlikely that late [cerebrovascular events] could be related to the valve prosthesis or procedure per se.”

Preventive Strategies Still Unteste

In a telephone interview with TCTMD, Dr. Rodés-Cabau cautioned that while the study reveals useful information by separating cerebrovascular events by their timing, it did not test “specific prevention measures.”

“We can say that the hyperacute (or acute) events seem to be more related to mechanical factors that occur during the procedure, and it’s interesting to see that the 2 main factors are balloon postdilation of the valve and valve embolization and dislocation,” he said. “I think that it makes sense.”

The study highlights the fact that even within the first 30 days there appear to be 2 time frames for cerebrovascular events arising from different mechanisms, Dr. Rodés-Cabau stressed. “We have to think differently when we want to prevent these hyperacute events compared to the more subacute events.”

Dr. Rodés-Cabau pointed out hemorrhagic strokes were more predominant among late events. “Maybe one of the things we have to think about is that in these patients we have to be cautious in terms of overtreating them with antithrombotic therapy. We need to anticoagulate these patients with chronic [A-fib], but especially when using combinations of different drugs, we have to be careful because they are at risk not only of ischemic events, which are much more frequent, [but also of bleeding].”

That being said, most of the late risk can be attributed to the fact that this population is older and sicker, rather than TAVR, he concluded, although a matched, non-TAVR population would most likely have a similar overall stroke rate.

 

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Source:
Nombela-Franco L, Webb JG, de Jaegere P, et al. Timing, predictive factors and prognostic value of cerebrovascular events in a large cohort of patients undergoing transcatheter aortic valve implantation. Circulation. 2012;Epub ahead of print.

 

 

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