Figure 8.

Imaging of myocardial motion reveals mechanical deformation within normal to near‐normal QRS hearts before systemic heart failure. Speckle‐tracking echocardiography detected myocardial mechanical disturbance as early as 2 weeks poststress in ATP‐sensitive K⁺ channel–deficient cardiomyopathy (A), at time point when electrocardiographic and systemic abnormalities were not yet prominent (B). Sample sizes were 10 before stress imposition (Pre), 15 at 2 weeks, and 5 in 3 months poststress. *P<0.05 vs Pre. Delay indicates intraventricular delay; HF, heart failure; LV, left ventricle; maximal Vo₂, maximal oxygen consumption; TAC, transverse aortic constriction.