Cardiac Long-Axis Function. Experimental and Clinical Aspects.

This thesis includes both experimental and clinical projects. The experimental studies investigate pathophysiological aspects of ventricular longitudinal function and therapeutic hypothermia during acute myocardial infarction (AMI). The clinical projects investigate the ability of ventricular longitudinal function variables to predict mortality and morbidity in patients with heart failure and reduced ejection fraction (HFrEF).

Study I involves two experimental models of acute myocardial infarction (AMI), namely an ischemia/reperfusion model and a microembolization model. The aim is to investigate the relationship of stroke volume to ventricular longitudinal function in the two models of AMI. The main finding is that stroke volume closely follows the ventricular longitudinal function after infarction in both experimental models. This highlights the link between ventricular longitudinal function and cardiac performance.

Study II involves an experimental model of ischemia/reperfusion injury. The aim is to investigate changes in ventricular energetics using non-invasive pressure-volume loops after therapeutic hypothermia during AMI. The main finding is that hypothermia (<35°C) adjunct to reperfusion yields preserved cardiac volumes and work. Furthermore, this effect was not fully explained by reductions in infarction sizes.

Study III investigates the ability of ventricular longitudinal function, measured as atrioventricular plane displacement (AVPD) and global longitudinal strain (GLS), to predict mortality in patients with HFrEF. The main finding is that AVPD and GLS exceed well-known clinical risk factors such as ejection fraction and late gadolinium enhancement as predictors of mortality using standard survival analyses.

Study IV builds upon the investigation from Study III and focuses on the ability of AVPD and GLS to predict cardiovascular morbidity with methodologies that incorporates reoccurring events. The results show that AVPD and GLS are valuable predictors of morbidity when using reoccurring event analyses.