Changes in the initial slope of the QRS in ischemic patients and normal subjects undergoing scintigraphy withdipyridamole

The effect of dipyridamole (Dp) on the linear portion of the first major deflection of the QRS in human electrocardiograms (which we refer to as Fslope) was investigated in the context of myocardial perfusion imaging (MPI), in normal subjects (NS, n=19) and in patients with cardiovascular ischemia (as manifested by a positive MPI scan, n=53). In the majority of participants, Fslope decreased (84% of 19 NS and 77% of 53 patients, p=0.69). The decrease in Fslope was more pronounced in patients with ST–T deviation as compared to those without (32.6±24.5 vs. 22.4±23.1, p=0.24), and in patients vs. NS (24.9±23.5 vs. 19.6±23.4, p=0.44). A change in Fslope is a sensitive (but not specific) measure for detecting the effect of Dp on the myocardium in the setting of scintigraphy.