Evolution and prognostic impact of low flow after transcatheter aortic valve replacement

Low flow (LF), defined as stroke volume index (SVi) <35 mL/m(2), prior to the procedure has been recently identified as a powerful independent predictor of early and late mortality in patients undergoing transcatheter aortic valve replacement (TAVR). The objectives of this study were to determine the evolution of SVi following TAVR and to assess the determinants and impact on mortality of early postprocedural SVi (EP-SVi).

We retrospectively analysed the clinical, Doppler echocardiographic and outcome data prospectively collected in 255 patients who underwent TAVR. Echocardiograms were performed before (baseline), within 5 days after procedure (early post procedure) and 6 months to 1 year following TAVR (late post procedure).

Patients with EP-SVi <35 mL/m(2) (n=138; 54%) had increased mortality (HR 1.97, p=0.003) compared with those with EP-SVi ≥35 mL/m(2) (n=117; 46%). Furthermore, patients with baseline SVi (B-SVi) <35 mL/m(2) and EP-SVI ≥35 mL/m(2), that is, normalised flow, had better survival (HR 0.46, p=0.03) than those with both B-SVi and EP-SVi <35 mL/m(2), that is, persistent LF, and similar survival compared with those with both B-SVi and EP-SVi ≥35 mL/m(2), that is, maintained normal flow. In a multivariable model analysis, EP-SVi was independently associated with increased risk of mortality (HR 1.41 per 10 mL/m(2) decrease, p=0.03). The preprocedural/intraprocedural factors associated with lower EP-SVi were lower B-SVi (standardised β [β] 0.36, p<0.001) atrial fibrillation (β -0.13, p=0.02) and transapical approach (β -0.22, p<0.001).

The measurement of EP-SVi is useful to assess the immediate haemodynamic benefit of TAVR and to predict the risk of late mortality.