Diagnostic utility of velocity ratio for paradoxical low-flow/low-gradient aortic stenosis

Background: Calcification score by cardiac computed tomography (CT) is required for diagnosis of paradoxical low-flow/low-gradient (PLFLG) aortic stenosis (AS). According to the guideline, velocity ratio (VR) < 0.25 by echocardiography is defined as severe AS, but utility of VR in patients with PLFLG AS remains unknown. This retrospective study was therefore conducted to investigate the utility of VR for a diagnosis of severe AS based on CT in patients with PLFLG AS.

Methods: We studied 58 patients with PLFLG AS. Severity of AS was defined as calcium score derived from cardiac CT.

Results: Of the 58 patients, 28 (48.3%) were diagnosed with severe AS based on CT, while 23 of them (82.1%) had VR < 0.25. It was noteworthy that receiver operating characteristic curve analysis showed that the optimal VR cutoff value for a diagnosis of severe AS was 0.25, with an area under the curve of 0.870 (P < 0.001). Sensitivity, specificity, positive predictive value, and negative predictive value of VR < 0.25 for a diagnosis of severe AS were 82.1%, 86.7%, 85.2% and 83.9%, respectively. Furthermore, patients who match the value of VR and severity of AS based on CT had higher prevalence of atrial fibrillation, higher serum brain natriuretic peptide concentration, larger left ventricular end-diastolic volume, and left ventricular stroke volume index.

Conclusion: The measurement of VR is simple, and VR < 0.25 can be used for diagnosis of patients with PLFLG AS as severe. Our findings may thus have clinical implications for routine clinical practice.