Myocardial Injury Common After TAVR

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Procedure-related myocardial injury after transcatheter aortic valve replacement (TAVR) increases key cardiac enzymes, according to data published in the June 2012 issue of Circulation: Cardiovascular Interventions. When the injury surpasses a certain threshold, it is an independent predictor of 30-day mortality.

For the prospective, observational study, investigators led by Jan Baan Jr, MD, PhD, of the Academic Medical Center (Amsterdam, The Netherlands), assessed the incidence, predictors, and prognostic value of myocardial injury in 119 patients with severe aortic stenosis who were implanted with a third-generation 18-Fr CoreValve device (Medtronic, Minneapolis, MN) at their institution between October 2007 and June 2011. All procedures were performed via transfemoral access.

Biomarker Increases for All

After TAVR, serum levels of creatine kinase-MB (CK-MB) and troponin T increased to values above the upper reference limit (URL) in all patients. CK-MB rose from 3.8 ± 1.3 ng/mL at baseline to a peak of 15.9 ± 15.8 ng/mL at a mean 9.5 hours after the procedure, while cardiac troponin T increased from 0.04 ± 0.03 ng/mL to a peak of 0.28 ± 0.30 ng/mL at a mean 14.3 hours after TAVR (P < 0.0001 for both increases).

Overall, 20 patients (17%) had postprocedural peak values greater than 5 times the URL for 1 or both cardiac markers, reaching the study-defined threshold for myocardial injury. However, no periprocedural MIs were deemed to have occurred according to Valve Academic Research Consortium criteria, because no new Q waves or echocardiographically determined new wall motion abnormalities were observed.

Multiple Predictors Identified for Myocardial Injury

Independent predictors of myocardial injury were:

  • Beta-blocker use (OR 0.12; 95% CI 0.03-0.45; P = 0.002)
  • Peripheral arterial disease (OR 6.36; 95% CI 1.56-25.87; P = 0.010)
  • Deeper prosthesis implantation (OR 1.31; 95% CI 1.08-1.59; P = 0.007)
  • Longer procedural duration (OR 1.04; 95% CI 1.01-1.06; P = 0.005)

The 30-day mortality rate was 13%. On multivariate analysis, independent predictors were:

  • Myocardial injury (OR 8.54; 95% CI 2.17-33.52; P = 0.002)
  • Preprocedural hospitalization (OR 9.36; 95% CI 2.55-34.38; P = 0.001)
  • Left ventricular mass index (OR 1.02; 95% CI 1.00-1.03; P = 0.035)

Kaplan-Meier estimates showed reduced survival among patients with myocardial injury out to 1 year, although the authors note that the effect on cumulative mortality primarily reflects the complication’s large impact on 30-day rates. Predictors of 1-year mortality overlapped those for 30-day mortality with the addition of preprocedural mean aortic valve pressure gradient (HR 0.97; 95% CI 0.94-1.00; P = 0.033).

An Issue of Supply and Demand

According to the authors, periprocedural myocardial damage during TAVR is likely due in large part to mismatch between myocardial oxygen supply and demand.

Reduced “oxygen supply may result from temporary aortic valve occlusion during balloon valvuloplasty and from hypotension by rapid ventricular pacing, bradycardia due to cardiac conduction disorders, and theoretically from distal embolization into the coronary (micro)circulation,” the investigators explain. On the other side of the equation, the study authors add, increased oxygen demand during TAVR may stem from a short-term increase in aortic regurgitation, exposure to intravenous inotropic agents, and tachycardia.

Dr. Baan and colleagues note that because the extent of myocardial injury after TAVR is relatively small and does not impair myocardial function or cause dangerous ventricular arrhythmias, the connection between myocardial injury and 30-day mortality risk remains unclear. “It is, therefore, more likely that the amount of myocardial injury is a reflection of more extensive disease . . . that makes a patient susceptible [to] postprocedural cardiovascular morbidity and mortality,” they hypothesize.

In these susceptible patients, the authors suggest that reducing procedure duration, administering beta blockers, and avoiding deep prosthesis insertion may improve clinical outcome.

Injury Common to Both Valve Types

For Josep Rodés-Cabau, MD, of Laval University (Quebec City, Canada), the most important finding is that the phenomenon of widespread myocardial injury has been shown to apply to the entire TAVR field.

“The concept has already been proven for the balloon-expandable valve from our work,” he told TCTMD in a telephone interview, citing his own research on the Sapien and Sapien XT devices (Edwards Lifesciences, Irvine, CA). “And now it has been proven for implantation of the self-expanding valve.”

On the other hand, he cautioned, data on the predictors of myocardial injury and its prognostic value are primarily hypothesis generating. “They make sense, but we need many more patients before we can draw definite conclusions,” he said, noting that comparable studies of myocardial injury after PCI involved many thousands of patients.

In addition, Dr. Rodés-Cabau pointed out that the relationship between myocardial injury and mortality risk is continuous, and the cutoff of 5 times the URL used in the study seems arbitrary.

Future studies might evaluate the potential effect of microembolization to the coronary tree, Dr. Rodés-Cabau suggested. “After all, we have a lot of emboli at the level of the brain,” he said, referencing MRI studies that show cerebral ischemic defects in about two-thirds of TAVR patients. “Why [wouldn’t this be the case] at the level of the coronary arteries?”

The aortography performed by the study investigators, however, is inadequate for such an assessment, he added.

Preventive Measures Premature

As for possible steps to minimize myocardial injury, Dr. Rodés-Cabau was cautious. It is premature to recommend use of beta blockers, he said, and hastening the procedure could lead to mistakes with worse consequences than biomarker bumps. Although some researchers have suggested forgoing balloon valvuloplasty before implantation to shorten procedure time and avoid an episode of hypotension from rapid pacing, any benefit has yet to be proven.

“It is clear now that there is a collateral effect of TAVR irrespective of valve type,” Dr. Rodés-Cabau concluded. “We have to continue to learn in terms of predictors and potential prevention of this phenomenon.”

Study Details

Patient age was 80.7 ± 7.8 years, and Society of Thoracic Surgeons score was 6.1 ± 4.5. In addition, 39% were men. Procedures lasted 80 ± 23 minutes.

 


Source:
Yong ZY, Wiegernick EMA, Boerlage-van Dijk K, et al. Predictors and prognostic value of myocardial injury during transcatheter aortic valve implantation. Circ Cardiovasc Interv. 2012;5:415-423.

 

 

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Myocardial Injury Common After TAVR

Procedure related myocardial injury after transcatheter aortic valve replacement (TAVR) increases key cardiac enzymes, according to data published in the June 2012 issue of Circulation Cardiovascular Interventions. When the injury surpasses a certain threshold, it is an independent predictor of
Disclosures
  • Dr. Baan reports no relevant conflicts of interest.
  • Dr. Rodés-Cabau reports serving as a consultant to Edwards Lifesciences and St. Jude Medical.

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