Incidence and clinical significance of ST segment depression in supraventricular tachycardia.

To evaluate the clinical significance of ST segment depression observed during paroxysmal supraventricular tachycardia, the data of 100 patients who underwent electrophysiologic testing between 1981 and 1986 in the drug free state were reviewed. Twelve lead electrocardiograms were taken within 20 s of tachycardia induction. Patients with antidromic tachycardia, tachycardia using multiple accessory pathways or tachycardia associated with bundle branch aberration or concomitant electrolyte abnormalities were excluded from the study. Significant ST depression was defined as at least 0.1 mV horizontal or downsloping or 0.2 mV upsloping depression, measured 80 ms after the J point. ST segment changes were correlated with historical data and the results of exercise tests and radionuclide or coronary angiograms. There were 52 males and 48 females, aged 11 to 67 years (mean 32.8 +/- 13.2). Tachycardia was due to atrioventricular reentry via an overt or concealed accessory pathway in 85 patients, and atrioventricular nodal reentry in 15 patients. Significant ST depression was seen in 51 patients (aged 11 to 65 years). Thirty-three of 70 patients younger than 40 years old had significant ST depression. There was no relationship between the presence of significant ST depression and age, sex, mechanism or rate of tachycardia. Only three patients had significant coronary artery disease, and all manifested significant ST depression during tachycardia. Thus the specificity of this finding was 51% and the predictive value only 6%. In conclusion, ST segment changes observed during narrow QRS complex tachycardia are common, nonspecific and a poor predictor of underlying coronary artery disease.