M.D./MSc Student Institut universitaire de cardiologie et de pneumologie de Québec (IUCPQ).Université Laval (IUCPQ-ULaval) Québec, Quebec, Canada
Background: Low-flow, low-gradient (LF-LG) aortic stenosis (AS) presents diagnostic and prognostic challenges, with limited tools for accurate risk stratification. Pulmonary vascular involvement, including elevated resistance and pulmonary hypertension, is associated with worse outcomes. We hypothesized that the pulmonary resistance index (PRI), represented by pulmonary artery pressure (PASP) to stroke volume (SV), is a good surrogate marker of ventricular–pulmonary arterial interaction and thus is associated with clinical outcomes in LFLG AS patients. This study aimed to evaluate the prognostic value of the PASP/SV in patients with LF-LG AS treated conservatively or with aortic valve replacement (AVR).
METHODS AND RESULTS:
Methods: Clinical and echocardiographic data were prospectively collected from 381 patients enrolled in the TOPAS (Truly or Pseudo-severe Aortic Stenosis- #NCT01835028). The receiver operating characteristic (ROC) curve was used to determine the optimal prognostic threshold of PASP/SV. The primary endpoint was the all-cause mortality 5-year follow-up.
Results: The PASP/SV parameter was measured in the entire cohort (mean age: 73 ± 9 years; 66% men). During a median follow-up of 1.5 (0.6–4.2) years, 144 patients (37%) died. The optimal prognostic threshold of PASP/SV was 0.54 mmHg/mL. In univariate Cox regression analyses, both continuous and dichotomized PASP/SV were associated with an increased risk of all-cause mortality (Hazard Ratio [HR] [95% CI]: 2.23 [1.54–3.21], p ≤ 0.001 and 3.33 [1.47–7.55], p = 0.004, respectively). This association remained significant in multivariable Cox analysis adjusted for age, sex, BMI, STS score and AVR as a time-dependent variable. Patients with PASP/SV > 0.54 mmHg/mL had a significantly higher risk of 5-year all-cause mortality compared to those with PASP/SV < 0.54 mmHg/mL (HR [95% CI]: 2.64 [1.15–6.04], p = 0.02). Additionally, PASP/SV was significantly associated with the composite outcome of all-cause mortality and AVR: HR [95% CI] = 1.68 [1.17–2.42], p = 0.005 in univariate analysis, and HR [95% CI] = 1.48 [1.02–2.14], p = 0.039 in multivariable analysis adjusted for age, sex, STS score and AVR as a time-dependent variable.
Conclusion: This study suggests that the PRI, defined as the PASP/SV ratio, is a surrogate marker of pulmonary vascular load and may be useful to predict clinical outcome and enhance risk stratification in this challenging population.
