Screening for left ventricular systolic dysfunction using GP-reported ECGs

Background

Diagnostic echocardiography has poor access for patients with suspected heart failure. Pre-echocardiography screening with electrocardiograms (ECGs) is recommended as a means of targeting this scarce resource. There are data to support this policy when ECGs are interpreted by cardiologists but not by GPs.

Aim

To assess the value of GP-reported ECGs as a pre-echocardiography screening test for left ventricular systolic dysfunction (LVSD).

Design of study

Cross-sectional study of GPs' ECG reporting skills.

Setting

General practice, NHS in Scotland.

Method

A randomly selected, stratified sample of 123 Scottish GPs reviewed 180 ECGs (100 abnormal, 50 normal and 30 duplicate) from 150 patients with suspected heart failure. Forty-one patients had LVSD on echocardiography. GPs were required to categorise ECGs as normal or abnormal.

Results

Mean sensitivity was 0.94 (95% Cl = 0.92 to 0.95). Mean specificity 0.58 (95% Cl = 0.56 to 0.60). Mean positive predictive value (PPV) was 0.47 (95% Cl = 0.46 to 0.48). Mean negative predictive value (NPV) was 0.96 (95% Cl = 0.95 to 0.97). Mean likelihood ratio was 2.39 (95% Cl = 2.28 to 2.50). Seventy of 123 (57%) GPs achieved sensitivity of 0.9 and specificity of 0.5 for the detection of LVSD.

Conclusion

Most Scottish GPs have the skills to perform pre-echocardiography screening ECGs in patients with suspected LVSD. However, differences in ECG reporting performance between individual GPs will result in widely varying referral rates for echocardiography and differences in the detection rate of LVSD. The implications of these findings need to be considered when heart failure diagnostic services are being developed.