Early electrocardiographic diagnosis of acute coronary ischemia on the paced electrocardiogram.

Background: Twelve-lead electrocardiography (ECG) is the most important source for the early diagnosis of an acute myocardial ischemia. However, its diagnostic value when the sequence of ventricular activation is altered by ventricular pacing is unknown. The aim of the study was to evaluate the ECG changes on the paced ECG during percutaneous coronary intervention (PCI) by doing temporary pacing.
Methods and Results: Standard 12 lead baseline and temporary pacing ECG records were taken before the intervention in elective PCI patients. Standard 12 lead and temporary pacing ECG records were repeated during the balloon inflation. Fifteen (12 men and 3 women; age 57.2+/-9.7 years) subjects who were undergoing routine PCI were studied. Mean Delta ST deviation on the normal conduction ECG during inflation was 1.03+/-1.02 mV and mean Delta ST deviation on the paced ECG during inflation was 1.7+/-1.6 mV. The pre-inflation mean QRS duration on the paced ECG was 143.2+/-2.8 ms and during inflation mean QRS duration was 157.8+/-12.5 ms. The mean QRS prolongation was 14.6+/-13.6 ms on the paced ECG. Despite the presence of paced ECG abnormalities, significant ischemic ST segment deviations were seen after referencing the ST segment deviations to the pre-PCI. Also, there is significant QRS prolongation on the paced ECG during ischemia.
Conclusions: The present study extends the correlation between normal and paced ECG during ischemia and the QRS prolongation could be a marker of myocardial ischemia on the paced electrocardiogram.