Myocardial work index: a marker of left ventricular contractility in pressure‐ or volume overload‐induced heart failure

Aims While global longitudinal strain (GLS) is considered to be a sensitive marker of left ventricular (LV) function, it significantly influenced by loading conditions. We hypothesized that myocardial work index (GMWI), novel LV may show better correlation with load-independent markers contractility in rat models pressure-induced or volume overload-induced heart failure. Methods and results Male Wistar rats underwent either transverse aortic constriction (TAC; n = 12) aortocaval fistula creation (ACF; 12), inducing pressure overload, respectively. Sham procedures were performed establish control groups (n 12/12). Echocardiographic loops obtained determine GLS GMWI. Pressure-volume analysis transient occlusion the inferior caval vein was carried out calculate preload recruitable stroke (PRSW), ‘gold-standard’ parameter contractility. Myocardial samples collected assess interstitial perivascular fibrosis area also atrial-type natriuretic peptide (ANP) brain-type (BNP) relative mRNA expression. Compared controls, substantially lower TAC group (−7.0 ± 2.8 vs. −14.5 2.5%; P < 0.001) only mildly reduced ACF (−13.2 2.4 −15.4 2.0%, 0.05). In contrast these findings, PRSW GMWI comparable sham (110 26 116 68 mmHg; 1687 275 mmHg% 1537 662 mmHg%; both NS), while found (58 14 111 40 1328 411 1934 308 mmHg%, 0.01). pooled population, (r 0.70; but not −0.23; 0.12) showed strong PRSW. correlated 0.61; 0.54; 0.001), ANP 0.85; BNP expression 0.75; demonstrated no marginal parameters. Conclusions Being conditions, reliable failure induced overload. reflects haemodynamic overload states, making more robust systolic should as an integrative marker, incorporating state, adverse tissue remodelling LV.