Resting echocardiographic predictors for true-severe aortic stenosis in patients with low-gradient severe aortic stenosis: A dobutamine stress echocardiography study

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.

Additive value of the right parasternal view for the assessment of aortic stenosis

BACKGROUND

Although Doppler evaluation using a multiplanar method is recommended to assess the severity of aortic stenosis (AS) with transthoracic echocardiography, evidence on the diagnostic significance of a non-apical method is limited. This study aimed to compare the use of the apical with the use of the right parasternal view (RPV) method to evaluate AS severity and to examine the diagnostic significance of performing the RPV method in addition to the apical method during the evaluation.

METHODS

This retrospective observational study included 276 consecutive patients (mean age: 79 ± 10 years; women, 56%) with severe AS (aortic valve area [AVA] ≤1.0cm² ). The severity of AS according to the apical method and that according to the RPV for all subjects were compared, and the significance of performing the RPV method in addition to the apical method was examined. Furthermore, we compared the concordance group, in which the apical and RPV methods indicated matching in severity, and the discordant group, in which the apical and RPV methods did not indicate matching severity.

RESULTS

Peak velocity (V_max ), mean pressure gradient (MG) were significantly higher and the AVA, AVAi, and Doppler velocity index (DVI) were significantly smaller when the RPV was added to the apical view. Performing the RPV method in addition to the apical method significantly decreased the number of low PG AS cases (MG < 40 mmHg) from 69.9% to 65.0% and it increased the number of very severe AS cases (V_max ≥ 5 m/s) from 8.7% to 14.5%. Deviation of Doppler angle was significantly greater in the discordant group compared to the concordant group (22.5 ± .6 vs. 31.8 ± 1.7, p < .001).

CONCLUSIONS

By performing the RPV method in addition to the apical method to determine AS severity, the diagnosis of AS to be resolved in approximately 10% of cases. These results suggest that AS severity may be underestimated by using the apical method alone.