Changes in the slope of the first major deflection of the ECG complex during acute coronary occlusion.

To evaluate the effect of acute coronary occlusion (ACO) during percutaneous coronary intervention (PCI) on the slope of the first major deflection of the QRS complex (the initial QRS slope). Standard ECG signals of 18 patients (89 leads), undergoing PCI were recorded prior to and during ACO. The initial QRS slope was calculated in the baseline state and during ACO. Changes in the standard ECG were detected in 36 of 89 leads (40%). The initial QRS slope during ACO was significantly different from baseline in 74 of 89 leads (83%). The specificity of the change in the slope during ACO was low (29%).