Myocardial injury following TAVI

Myocardial injury following TAVI

Myocardial injury following transcatheter aortic valve implantation (TAVI) can occur due to various reasons:

1. Myocardial tissue compression can occur due to balloon inflation and by the valve prosthesis.
2. Short episodes of extreme hypotension and global myocardial ischemia occurs during the balloon valvuloplasty and valve implantation.
3. As a rare occurrence, coronary ostia can be compromised by the valve prosthesis.

TAVI can be done by the trans femoral as well as the trans apical route. Trans apical route involves the puncture of the left ventricular apex and passage of large catheters through it which can also cause direct myocardial injury. Hence myocardial injury is more likely with trans apical route. Higher myocardial injury is associated with lower improvement in left ventricular ejection fraction after the procedure. Rodés-Cabau J and associates [1] evaluated the incidence, predictive factors and prognostic value of myocardial injury after uncomplicated TAVI. They found that the transapical approach and baseline renal dysfunction were associated with higher increase in biomarkers of myocardial injury. It was noted that some degree of myocardial injury was noted in 97% in the transfemoral group and all of the trans apical group of patients undergoing TAVI. It has been suggested earlier that using self expandable valve avoids the rapid pacing and extreme hypotension during valve expansion and may reduce myocardial injury. A higher degree of over dimensioning of the prosthesis with respect to the aortic annulus also leads to more stretching of the basal myocardium and higher degrees of myocardial injury. Coronary embolism by small microparticles from the native valve during balloon inflation can also contribute to the myocardial injury. The usual definition of periprocedural myocardial infarction is elevation of CK-MB more than 3 times the upper limit of normal for percutaneous coronary interventions and more than 5 time for cardiac surgery. A similar cut off for TAVI is yet to be established. Rodés-Cabau J et al suggest that a CK-MB more than 3 times the upper limit of normal and a cTNT (cardiac troponin T) more than 15 times the upper limit of normal following TAVI may be clinically relevant and suggest periprocedural myocardial infarction following TAVI.

Reference

1. Rodés-Cabau J, Gutiérrez M, Bagur R, De Larochellière R, Doyle D, Côté M, Villeneuve J, Bertrand OF, Larose E, Manazzoni J, Pibarot P, Dumont E. Incidence, predictive factors, and prognostic value of myocardial injury following uncomplicated transcatheter aortic valve implantation. J Am Coll Cardiol, 2011; 57:1988-1999.