Early right ventricular dysfunction after transcatheter aortic valve replacement (TAVI): a prospective cardiac magnetic resonance study of open versus transcatheter aortic valve replacement

Abstract

Introduction: Recent published literature has validated the use of transcatheter aortic valve implantation (TAVI) in high-risk patients with aortic stenosis. These trials and registries have largely focused on combined morbidity and mortality outcomes with little focus given to impact on early myocardial function. We assessed effects on myocardial function, reversible and irreversible myocardial injury of both transcatheter and open aortic valve replacement utilizing multi-parametric CMR and biochemical markers. Methods: We conducted a prospective comparative study of 24 patients (14 male) with severe aortic stenosis undergoing either transcatheter valve replacement (12 patients) or high risk (euroSCORE >20) open valve replacement (12 patients). CMR examination was carried out pre-operatively and within 2 weeks post-operatively. All scans used a Siemens Aera 1.5T system (Siemens, Germany). Images obtained included a standard cine functional imaging, T2 weighted images using LV basal, mid and apical SA slices and late gadolinium enhanced (LGE) images (Gadovist 0.1mg/kg). HS troponin was measured serially (pre, 4, 12, 24 and 48 hours post). Results: Mean ages were 79.7 years Open and 83.2 years TAVI. The postoperative scan was conducted at a median of 6 days for TAVI and 7 days for open. Mean preoperative LV ejection fraction was similar in the 2 groups (65.7+16.3 TAVI; 65.7+18.9 Open, p>0.05) After surgery, the LVEF was not significantly different in either group (TAVI: 65.7 vs 66.1, p>0.05; OPEN 65.7 vs 67.2 p>0.05) In contrast, RVEF decreased significantly in the TAVI group (58.9 to 48.2, p0.04), driven largely by significantly higher RVEDV comparative to the open group (95.4+30.5 vs 88.3+24.3 p0.05). The open AVR group had no significant change in RVEF. There was no RV irreversible injury in either group. 2 patients in TAVI group and 1 patient in open AVR group demonstrated new LV irreversible injury (p>0.05). T2 analysis showed abnormal global myocardial enhancement in 16.6% of cases in the TAVI group and 8.3% in the open group (p>0.05). Median HS troponin at 48hrs was significantly larger in the open AVR group (403 vs 193ng/L, p<0.05) Conclusion: Although serum Troponin levels are higher in open AVR (likely reflecting use of cardiopulmonary bypass), there is no increased CMR detected LV myocardial oedema or necrosis compared with TAVI. In the absence of new RV irreversible myocardial injury, it is likely that the RV dysfunction seen in the TAVI group is a result of rapid ventricular pacing during device insertion, resulting in myocardial stunning.