Correlation of Auscultatory Severity of Aortic Stenosis with Trans Thoracic Echocardiography (CASSETTE): Pilot study for tele-stethoscopy in rural or global health applications

Abstract

Objectives: This pilot study seeks to evaluate the utility of an electronic stethoscope in assessing the severity of isolated aortic stenosis.

Methods: Echocardiograms for 653 patients with aortic stenosis were screened. 50 patients with isolated aortic stenosis were enrolled in the study. Patients were excluded for more than mild non-aortic valvular disease. Participants received an updated echocardiogram and cardiac recordings in the supine position were performed at four standard sites utilizing the Littmann 3200 electronic stethoscope. Recordings were analyzed using the Zargis Cardioscan® Software and the correlation of the aortic valve mean gradient by echocardiography to the time of peak systolic murmur (ASAI) averaged over the auscultative points was obtained.

Results: 36 enrolled subjects met the criteria for study inclusion. The ASAI was averaged across each site and compared to the mean aortic gradient. A receiver operator characteristic curve was calculated for an ASAI value, which reliably predicted a mean pressure gradient of >30mmHg. An ASAI of 33 gave a sensitivity of 1.0 and a specificity of 0.72 with a corresponding negative predictive value of 100% and a positive predictive value of 47%.

Conclusion: In patients with greater than mild aortic stenosis without other significant valve disease, the Littmann 3200 stethoscope and Cardioscan software package provides an easy to use screening tool for aortic valve stenosis severity. With continued validation, electronic stethoscope monitoring would provide cheap, reliable and instantaneous surveillance for aortic stenosis in remote areas with constrained medical assets or for patients without access to care.