Usefulness of Aortic Valve Calcification in Patients With Low-Flow Aortic Stenosis

Aortic valve calcification (AVC) has been shown to be a powerful assessment of aortic stenosis (AS) severity and a predictor of adverse outcomes. However, its accuracy in patients with low-flow AS has not yet been proven. The objective of the study was to assess the predictive value of AVC in patients with classical low-flow (CLF, that is, low-flow reduced left ventricular ejection fraction) or paradoxical low-flow (PLF, that is, low-flow preserved left ventricular ejection fraction) AS.

We prospectively included 641 patients, 319 (49.8%) with CLF-AS and 322 (50.2%) with PLF-AS, who underwent Doppler echocardiography and multidetector computed tomography. AVC ratio (AVCratio) was calculated as AVC divided by the sex-specific AVC threshold for AS severity; AVC score ≥2000 Agatston units in male patients and ≥1200 Agatston units in female patients. The primary end point of the study was all-cause mortality regardless of treatment.

Sex-specific AVC thresholds identified AS severity correctly in 137 (87%) of the patients. During a median follow-up of 4.9 (4.3-5.9) years, there were 265 deaths. After comprehensive adjustment, AVCratio was associated with all-cause mortality in patients with CLF-AS (adjusted hazard ratio, 1.25 [95% CI, 1.01-1.56]; P=0.046) and PLF-AS (adjusted hazard ratio, 1.51 [95% CI, 1.14-2.00]; P=0.004). There was an interaction (P=0.001) between AVC and AS flow patterns (ie, CLF versus PLF) with regard to the prediction of mortality. The best AVCratio threshold to predict mortality was different in patients with CLF-AS (AVCratio ≥0.7) and PLF-AS (AVCratio ≥1). After a comprehensive analysis, AVCratio as a dichotomic variable was associated with all-cause mortality in all groups (P≤0.001). The addition of AVCratio to the models improved all models' predictive value (all net reclassification index >18%; all P≤0.05).

In patients with CLF-AS or PLF-AS, AVC is a major predictor of mortality. Thus, AVC should be used in low-flow patients to assess AS severity and stratify risk. Importantly, in patients with reduced left ventricular ejection fraction, a nonsevere AS (ie, AVC 70% of severe) could be associated with reduced survival.