Why LV dilatation with vasodilator stress in hypertrophic cardiomyopathy?

Excerpt

Transient ischemic dilatation (TID) of the left ventricle (LV) on vasodilator stress perfusion images is a concerning sign. In some, TID may reflect global subendocardial hypoperfusion during stress.1 A reduction in subendocardial perfusion results in an increase in observed chamber size on the stress images and the finding of TID. However, in patients with advanced coronary disease (CAD), TID during vasodilator stress might also reflect transient LV dysfunction due to generation of an actual myocardial oxygen supply/demand imbalance (true ischemia). TID on vasodilator stress PET perfusion images has previously been correlated with impaired myocardial perfusion reserve and with an acute decline in LV systolic function during stress.2 Moreover, patients with TID on vasodilator PET images exhibit poorer clinical outcomes as compared to those without TID who have similar LV ejection fractions and perfusion defect scores.3 Thus, TID on vasodilator stress images in CAD patients may reflect global subendocardial hypoperfusion, induction of a true oxygen supply/demand imbalance with ischemic LV dysfunction, or both. …