Extracellular volume fraction (ECV) derived from pre-operative computed tomography predicts prognosis in patients undergoing transcatheter aortic valve implantation (TAVI)

Aims: Transcatheter aortic valve implantation (TAVI) is the treatment of choice for high-risk patients with severe aortic stenosis (AS). A portion of TAVI recipients has no long-term clinical benefit, and myocardial fibrosis may contribute to unfavourable outcomes. We aimed to assess the prognostic value of an interstitial fibrosis marker, extracellular volume fraction (ECV), measured at planning computed tomography (CT) before TAVI. Methods and results: From October 2020 to July 2021, 159 consecutive patients undergoing TAVI planning CT were prospectively enroled. ECV was calculated as the ratio of myocardium and blood pool differential attenuations before and 5 min after contrast administration, pondered for haematocrit. A composite endpoint including heart failure hospitalization (HFH) and death was collected by telehealth or in-person follow-up visits in the 113 patients constituting the final study population. Cox proportional hazards model was used to assess association between ECV and the composite endpoint. Median follow-up was 13 (11-15) months. The composite endpoint occurred in 23/113 (20%) patients. These patients had lower aortic valve mean pressure gradient [39 (29-48) vs. 46 (40-54) mmHg, P = 0.002] and left ventricular and right ventricular ejection fraction [51 (37-69) vs. 66 (54-74)%, P = 0.014; 45 (31-53) vs. 49 (44-55)%, P = 0.010] and higher ECV [31.5 (26.9-34.3) vs. 27.8 (25.3-30.2)%, P = 0.006]. At multivariable Cox analysis, ECV higher than 31.3% was associated to increased risk of death or HFH at follow-up (hazard ratio = 5.92, 95% confidence interval 2.37-14.75, P < 0.001). Conclusion: In this prospective observational cohort study, ECV measured at TAVI planning CT predicts the composite endpoint (HFH or death) in high-risk severe AS patients.