Is myocardial viability related to left ventricular dyssynchrony?

Excerpt

The role of cardiac dyssynchrony in coronary artery disease (CAD) is still not well defined. Several studies have evaluated the relation of left ventricular dyssynchrony (LVD) with myocardial ischemic and/or scar burden,1-4 CAD extent,5 and LV contractile function.6 However, there are conflicting data in the literature about the effect of different patterns of perfusion abnormality on LVD in CAD patients. On initial stress-rest Tc99m-MIBI study, no significant relation between LVD and stress-induced ischemia was observed and this was attributed to delayed image acquisition after stress.3 So, it was proposed, that stress-induced changes in LVD may be better evaluated using Thallium-201 (Tl-201) MPS, as the post-stress images are acquired within 10 minutes of stress in Tl-201 study. Chen et al evaluated this aspect on stress-rest Tl-201 MPS and suggested that stress-induced ischemia causes dyssynchronous contraction in the ischemic region, leading to worsening of LVD, whereas normal myocardium showed more synchronous contraction during stress.4 However, in a similar study, Singh et al found that LVD parameters were smaller on post-stress as compared to rest study on Tl-201 MPS, regardless of the perfusion pattern. Stress-induced worsening of LVD was observed only in patients with perfusion abnormalities, but this is not related to the type of perfusion abnormality.2 Therefore, there is still a lack of clarity on the exact relationship of the LVD with the type of perfusion abnormalities. …