Transcutaneous electrical nerve stimulation can increase resting coronary blood flow velocity. The findings suggest that the site of action is at the microcirculatory level and that the effects may be mediated by neural mechanisms.

Patients with syndrome X who present with unstable angina have a significantly better functional prognosis than those presenting with symptoms of stable angina. This may reflect differences in underlying pathophysiological mechanisms.

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SummaryThe aim of this study was to assess the efficiency of exercise tests in identifying ischaemia in the territories supplied by the three main coronary arteries. We prospectively analysed 578 patients with single vessel coronary disease (>50% stenosis in one vessel and completely normal other vessels). Patients with single vessel coronary artery disease were divided into three groups: patients with significant left anterior coronary artery disease (group 1, n=234); patients with significant right coronary artery disease (group 2, n=201); patients with significant left circumflex disease (group 3, n=143). Our study, which is the largest prospective study of patients with angiographically documented single vessel coronary artery disease, suggests that the exercise electrocardiogram is a poor predictor of circumflex coronary artery ischaemia. In addition, the site of ST depression identified from the electrocardiogram was a poor predictor of the site of myocardial ischaemia. No single lead could distinguish between the three groups and the location of coronary stenosis could not be predicted by location of ST depression.Keywords: exercise electrocardiogram, coronary artery disease Exercise electrocardiography has now established itself as a major tool for the assessment of patients with suspected coronary artery disease. It has a sensitivity in the region of 68% (range 23-100%) and a specificity of 77% (range 17-100%) based on meta-analytical data.' The aim of this study was to assess the sensitivity of this technique in identifying ischaemia occurring in the presence of significant coronary stenosis in individual coronary arteries. MethodsWe prospectively analysed 578 patients with significant single vessel coronary disease who were investigated at our institution during the period of 1 October 1990 to 30 September 1993. Significant coronary artery disease was defined as > 50% stenosis in one coronary artery and normal other coronary arteries. Patients were divided into three groups: patients with significant left anterior descending coronary artery disease (LAD group); patients with significant right coronary artery disease (RCA group); and patients with significant left circumflex disease (LCX group). Patients with Q waves on the electrocardiogram (ECG), bundle branch block, interventricular conduction defect, left ventricular hypertrophy, associated valvular heart disease, or hypertrophic cardiomyopathy were excluded from the study. Exercise tests were performed using the standard Bruce Protocol prior to angiography in all patients (boxes 1 & 2). Three ECG leads were continuously monitored (V3, V5, and aVF) and 12-lead ECGs were obtained every three minutes and at peak exercise. The exercise ECG data were evaluated for the presence of exercise-induced ST depression by two independent, blinded investigators. The exercise test was said to be positive if there were > 1 mm ST segment depression 80 ms after the J point. DiscussionThis is the largest prospective study of patients with angiographically documented...