Transcatheter Aortic Valve Replacement Prognostication with Augmented Mean Arterial Pressure

Abstract

Background: Post-transcatheter aortic valve replacement (TAVR) patient outcome is an important research topic. To accurately assess post-TAVR mortality, we examined a family of new echo parameters (augmented systolic blood pressure (AugSBP) and arterial mean pressure (AugMAP)) derived from blood pressure and aortic valve gradients.

Methods: Patients in the Mayo Clinic National Cardiovascular Diseases Registry-TAVR database who underwent TAVR between 1 January 2012 and 30 June 2017 were identified to retrieve baseline clinical, echocardiographic and mortality data. AugSBP, AugMAP and valvulo-arterial impedance (Zva) (Zva) were evaluated using Cox regression. Receiver operating characteristic curve analysis and the c-index were used to assess the model performance against the Society of Thoracic Surgeons (STS) risk score.

Results: The final cohort contained 974 patients with a mean age of 81.4 ± 8.3 years old, and 56.6% were male. The mean STS risk score was 8.2 ± 5.2. The median follow-up duration was 354 days, and the one-year all-cause mortality rate was 14.2%. Both univariate and multivariate Cox regression showed that AugSBP and AugMAP parameters were independent predictors for intermediate-term post-TAVR mortality (all p < 0.0001). AugMAP1 < 102.5 mmHg was associated with a 3-fold-increased risk of all-cause mortality 1-year post-TAVR (hazard ratio 3.0, 95%confidence interval 2.0-4.5, p < 0.0001). A univariate model of AugMAP1 surpassed the STS score model in predicting intermediate-term post-TAVR mortality (area under the curve: 0.700 vs. 0.587, p = 0.005; c-index: 0.681 vs. 0.585, p = 0.001).

Conclusions: Augmented mean arterial pressure provides clinicians with a simple but effective approach to quickly identify patients at risk and potentially improve post-TAVR prognosis.

Keywords: STS risk score; aortic valve stenosis; augmented mean arterial pressure; mortality; transcatheter aortic valve replacement (TAVR).

Figure 1

Box plot of augmented blood pressure measurements. Panels (A–E) demonstrate the box plot of each augmented blood pressure parameter. Augmented blood pressure parameters were significantly higher in alive patients compared to deceased patients (all p < 0.0001). The formulas used to calculate each parameter are listed in the upper-right corner. Rhombus symbol represents cases distributed beyond 2.5 standard deviations.

Figure 2

Kaplan–Meier survival curve analysis. Panel (A). Patients with ≥median AugSBP1 had significantly better survival compared to patients with <median AugSBP1; the median AugSBP1 was 171 mmHg (HR 2.3, 95%CI: 1.6–3.4, log-rank p < 0.0001). Panel (B). Patients with ≥median AugMAP1 had significantly better survival compared to patients with <median AugMAP1; the median AugMAP1 was 102.5 mmHg (HR 3.0, 95%CI: 2.0–4.5, log-rank p < 0.0001).

Figure 3

The ROC curves of all the single-parameter prediction models against the STS risk score model. The ROC curves of all the single-parameter prediction models against the STS risk score model (AUC 0.587, 95%CI 0.521–0.649). The AugMAP1 model had the best performance (AUC 0.700, 95%CI 0.646–0.750, p = 0.005), followed by the AugMAP2 model (AUC 0.691, 95%CI 0.636–0.743, p = 0.009). The rest of the augmented blood pressure (AugMAP3, AugSBP1, AugSBP2) parameters were comparable to the performance of the STS risk score (larger AUC, no statistical significance). Valvulo-arterial impedance (Zva) had a smaller AUC than the STS risk score, but this was not statistically significant (AUC 0.559, 95%CI 0.502–0.611, p = 0.519). Blue dotted line is the identity line.