Mittal SR, Sharma D, Garg D. J.L.N. Medical College and Hospital, Ajmer, India. Int J Cardiol 1990 Feb;26(2):236-7. Effects of submaximal exercise were studied on the unipolar esophageal electrocardiogram recorded at ventricular level in 15 patients with essential hypertension who complained of chest discomfort on effort but had negative exercise stress tests using standard leads and lead CM5. Six patients developed horizontal or downsloping depression of the ST segment in the esophageal lead. The ischemic response might result from subcritical coronary stenosis in face of the increased myocardial oxygen demand of hypertrophied myocardium.