Preclinical Myocardial Dysfunction
Traditional imaging biomarkers may be normal in early subclinical disease, however reduced global longitudinal strain (GLS) related to subendocardial dysfunction is common. (Figure 1). The prevalence of reduced GLS in asymptomatic type 2 diabetes mellitus has been reported to range from 37% to 54% 8. Impaired longitudinal strain may be present prior to the onset of LV remodeling and hypertrophy 9. Furthermore, reduced longitudinal strain may exist despite normal or near normal conventional Doppler and tissue Doppler-derived parameters of diastolic function10(Figure 2). Compensatory subepicardial hypertrophy may develop in an effort to reduce subendocardial wall stress and preserve ejection fraction 11. Despite mild, resting impairment in longitudinal mechanics, those with preclinical myocardial dysfunction typically augment longitudinal strain to near normal values during exercise 12. Complex interactions between protracted risk factor exposure and progressive structural changes influence the progression from the asymptomatic phase to symptomatic heart failure. High risk structural findings in asymptomatic patients at elevated risk for progression to symptomatic disease include elevated E/e’, left ventricular hypertrophy (LVH), and abnormal GLS12.