Non-invasive means of evaluating appropriate cardiac unloading remain to be established. We hypothesized that myocardial deformation assessed by echocardiographic speckle-tracking strain analysis can reliably estimate the degree of left ventricular (LV) unloading under mechanical circulatory support. A total of 24 Yorkshire pigs underwent Impella-mediated acute LV unloading 1-2 weeks after myocardial infarction (MI). Echocardiographic and invasive pressure-volume measurements were used to evaluate the degree of LV unloading. Pressure-volume analysis before and after LV unloading exhibited a significant decrease in stroke work (3399 ± 1440 to 1244 ± 659 mmHg ml, p < 0.001), suggesting reduced external cardiac work. Both longitudinal strain (- 14.6 ± 4.1% to - 10.6 ± 2.3%, p < 0.001) and circumferential strain (- 18.7 ± 6.1% to - 9.3 ± 3.5%, p < 0.001) decreased after LV unloading, and there were linear relationships between stroke work and echocardiographic longitudinal (r = - 0.61, p < 0.001) as well as circumferential strains (r = - 0.75, p < 0.001). Echocardiographic LV strain analysis offers a non-invasive assessment of LV unloading in subacute MI.
Keywords: CS; Contraction; Ischemic heart failure; LS; Mechanical support; Sub-acute MI.