Tadeja Poropat Flerin

Background: Mechanical work is traditionally defined by the pressure–volume loop, but its invasive nature limits routine clinical use. The myocardial work index (MWI) has emerged as a non-invasive alternative, combining strain and estimated pressure to assess cardiac performance. However, MWI does not account for ventricular geometry and treats the ventricle as a dimensionless chamber. According to Laplace’s law, wall stress and the true myocardial load depend on both pressure and ventricular geometry. Therefore, this study aims to develop and evaluate a geometry-informed myocardial work framework that provides a more physiologically representative estimate of mechanical energy expenditure. Method: In this proof-of-concept study, mechanical work was calculated using the one-fiber model of the left ventricle (LV) with Laplace-based geometric correction, integrating fiber stress over strain to derive the tension-adjusted myocardial work (TAMW) model. Strain was obtained from speckle tracking echocardiography along with pressure data while LV volumes and wall geometry were obtained from cardiac MRI. Two acute myocarditis patients with compact and dilated ventricles were analyzed, comparing cumulative and instantaneous work between MWI and TAMW. Performance gaps were quantified as the percentage difference in peak cumulative work. Results: Conventional MWI differed substantially between two cases (2576 vs. 1795 mmHg%, performance gap: 33.3%) whereas TAMW reduced this discrepancy to 7.5% (10,806 vs. 9789 mmHg%). TAMW also highlighted differences in temporal distribution of instantaneous work relative to MWI, reflecting the influence of ventricular geometry on contraction dynamics. Conclusions: TAMW incorporates the influence of geometry in the myocardial work framework revealing a more physiologically consistent reflection of myocardial effort across different ventricular geometries.

Background: Coronary computed tomographic angiography (CCTA) provides information on coronary atherosclerosis burden and extent. In the present analysis, we compared the prognostic impact of coronary scores (maximal coronary stenosis, segment involvement score [SIS] and segment stenosis scores [SSS], and the CCTA-modified Duke score). Patients and methods: We retrospectively reviewed CCTA images of patients with suspected coronary obstruction and excluded patients who underwent planned revascularization. Using Cox multivariate analysis, we estimated the hazard ratio (HR) with 95% confidence intervals (CI) for different coronary scores to predict death, myocardial infarction, and late unplanned revascularizations (as individual and composite endpoints). Model performance was evaluated using area under time-dependent receiver operating characteristic curves (AUC). Results: We included 750 patients (median age 61 years, 54% women) with a median follow up 1,465 days. Unadjusted HR for major cardiovascular events ranged from 3.87 (95% CI 1.49–10.0, p = 0.005) for obstructive disease (> 50% stenosis in any vessel) to 1.17 (1.09–1.25, p < 0.001) for SIS (each additional segment involved). Predictions remained significant for all endpoints and after adjusting for coronary artery calcium score and risk factors. Area under curve (AUC) for coronary stenosis was 0.77 (95% CI 0.71–0.82), for SIS was 0.77 (95% CI 0.72–0.83), for SSS was 0.77 (95% CI 0.71–0.82), and for Duke score was 0.67 (95% CI 0.61–0.74). Conclusions: Our study has confirmed that coronary atherosclerosis burden and extent independently predict major cardiovascular events in patients who had undergone CCTA, but were not referred for invasive diagnostic procedures and revascularization.