Valvulo-arterial impedance is the best mortality predictor in asymptomatic aortic stenosis patients.

BACKGROUND AND AIM OF THE STUDY: Risk stratification is particularly complex in asymptomatic patients with significant aortic stenosis (AS). The study aim was to assess which hemodynamic/Doppler-echocardiographic parameter best predicts mortality in asymptomatic patients with severe AS and a normal left ventricular ejection fraction (LVEF).

METHODS: This prospective study included 128 consecutive asymptomatic patients (75 males, 53 females; mean age 66.35 ± 10.51 years) with severe AS (aortic valve area (AVA) ± 1.0 cm2) and a normal LVEF (55%). The patients were followed up for 47 months (median 35.5 months, IQR 7 months). Clinical data at follow up were obtained from all patients by either direct examination or telephone interview.

RESULTS: During the follow up, 55 patients (43.0%) underwent aortic valve replacement (AVR) surgery due to AS-related symptoms. Of the 12 patients that died (9.4%), eight deaths occurred before surgery (four patients refused operation), and one patient died after surgery due to postoperative infection. Those patients who died had a significantly higher valvulo-arterial impedance (Z(va)) (7.81 versus 4.86 mmHg x ml/m2, p < 0.001), a higher N-terminal pro-brain natriuretic peptide (NT-proBNP) level (1708.5 versus 376.5 pg/ml, p = 0.003) and a lower AVA (0.65 versus 0.86 cm2, p = 0.002), but there were no differences in LVEF, P(mean) or age between the groups (69.68% versus 72.24%, p = 0.206; 44.95 versus 41.75 mmHg; and 69 versus 66 years, p = 0.332, respectively). When parameters that were predictors of mortality according to univariate analysis were further analyzed with Cox multivariate analysis, Z(va) was found to be the best independent predictor (B = 0.460, HR = 1.584, 95% CI = 1.064-2.359, p = 0.024). A Z(va) value of 6.1 mmHg x ml/m2 was identified as the best (cut-off) predictive value for the occurrence of death, with a sensitivity 61.1% and a specificity 86.0%.

CONCLUSION: Z(va) is the best mortality predictor in asymptomatic patients with severe AS and a normal LVEF. Future studies are required to focus further on predictors of outcome, the aim being to achieve an optimal selection of asymptomatic patients considered to be at risk and who would benefit from early AVR.