Association between global myocardial work index and outcomes in nonischemic dilated cardiomyopathy

Left ventricular global longitudinal strain (LV-GLS) is associated with increased risk of adverse outcomes in nonischemic dilated cardiomyopathy (NIDCM). However, it can be altered by LV afterload. The global myocardial work index (GMWI) accounts for LV afterload and could improve risk discrimination when compared with LV-GLS. We sought to determine whether GMWI outperformed LV-GLS for risk stratification in patients with NIDCM.

We determined the association between GMWI and a combined endpoint of death or heart failure (HF) admission. We included 524 patients with NIDCM (median age 67 years, LVEF 35%), with a median GMWI of 968 mmHg%. Patients with lower GMWI had more frequent history of HF admission, higher E/e' ratio, and worse right ventricular function. During a median follow-up of 3.4 years, 171 had the endpoint. There was a significant and nonlinear relationship between GMWI and the endpoint, with a progressive increase in risk until values below 1000 mmHg% were reached, where the risk of the endpoint plateaued. GMWI was strongly collinear with LV-GLS, and both parameters demonstrated similar performance after adjustment, suggesting that GMWI adds little value in this population if LV-GLS has already been accounted for.

In patients with NIDCM, lower GMWI is associated with previous HF admission, worse echocardiographic parameters and higher risk of subsequent HF admissions and death, but it does not seem to improve discrimination when compared with LV-GLS.