Evaluation of a novel method for grading heart murmur intensity

Abstract

Objective: To determine if heart murmur intensity grading performance can be improved using the heart sounds as an internal reference.

Methods: Single-blind controlled trial of 100 medical students, residents, and pediatric attending physicians at a children's hospital. Groups of 1 to 3 participants were alternately assigned to intervention and control groups, reported their method of grading heart murmur intensity, and then graded the intensity of a random sample of 20 recorded murmurs on a 6-point scale. Before rating another random sample of 20 murmurs, the intervention group was taught a system that uses the heart sounds as an internal reference. Primary outcomes were change in accuracy (percentage correct), interrater agreement (kappa), and consistency (kappa). Subgroup analyses were performed by training level and heart murmur grade.

Results: Grading accuracy improved more in the intervention group than the control group (Delta improvement, 5%; 95% confidence interval [CI], -0.1%-10.0%]). This was most pronounced among attending physicians (Delta improvement, 11%; 95% CI, 0.4%-22%) and students (Delta improvement, 12%; 95% CI, 3%-20%) and for grade 2 murmurs (Delta improvement, 20%; 95% CI, 10%-31%). Relatively greater improvements in consistency were observed after the intervention for attending physicians (Delta improvement, 0.17; 95% CI, 0.01-0.32) and grades 2 (Delta improvement, 0.22; 95% CI, 0.09-0.36) and 3 murmurs (Delta improvement, 0.16; 95% CI, 0.05-0.28).

Conclusions: A system that uses the heart sounds as an internal reference for grading heart murmur intensity quickly improves accuracy and consistency for some providers and specific murmurs.