Correlation of ST Segment Elevation in the Lead aVR During tmt with Coronary Angiogram

BACKGROUND:Treadmill testing (TMT) is the most widely used method for evaluating patients with coronary artery disease, predicting the left main coronary artery (LMCA) disease before invasive procedure is very important in risk assessment because of its severe clinical outcome. Lead aVR can be very useful in identifying LMCA obstruction, it is also valuable lead not only in diagnosis but also in predicting the prognosis. AIM:-To examine whether ST elevation in lead aVR during TMT may suggest LMCA disease since the lead aVR is the reciprocal lead of LMCA . METHOD:In this study, 50 patients with positive TMT were included. The study group consisted of 30 patients with ST elevation of >1 mm in lead aVR. 20 patients also having positive TMT, but with <1mm of ST elevation in lead aVR comprised the control group. All patients underwent coronary Angiography. RESULTS:-Coronary angiography in the study group revealed significant LMCA disease in 19(63%) patients, whereas no LMCA disease in the control group. 6(20%) patients had ostioproximal LAD lesions in study group, 2(10%)patients in the control group. Tripple vessel disease in 5(17%)patients in study group, 3(15%)patients in the control group. Significant “P” value indicates ST segment elevation in lead aVR during TMT which strongly predicts the presence of LMCA disease. CONCLUSION:-ST segment elevation in the lead aVR of >1 mm during Treadmill testing(TMT)is a strong predictor of LMCA disease. INTRODUCTION :Lead aVR, one of the 12 electrocardiographic leads, is frequently ignored in clinical medicine . Infact, many clinicians refer to the 12-lead electrocardiogram (ECG) as the 11-lead ECG, noting the commonly held belief that lead aVR rarely offers clinically useful information.1 The augmented limb leads were developed to derive more localised information than the bipolar leads I, II and III could offer. For this purpose from the existing limb electrodes, new leads aVR, aVF and aVL were constructed, being unipolar leads looking at the right, left and lower part of the heart with the reference electrode constructed from the other limb electrodes. Thus, the purpose of lead aVR was to obtain specific information from the right upper side of the heart, such as the outflow tract of the right ventricle and the basal part of the septum. In practice, however, most electrocardiographers consider lead aVR as giving reciprocal information from the left lateral side, being already covered by the leads aVL, II, V5 and V6. This has been the reason that lead aVR has become largely ignored.2,3 Lead aVR can be very useful in identifying Left Main Coronary Artery (LMCA) obstruction.4 Ischaemia of the basal part of the interventricular septum is the electrocardiographic explanation for the occurrence of ST-segment elevation in this lead. In this situation, owing to the dominance of the basal ventricular mass, the ST-segment vector in the frontal plane points in a superior direction, leading to ST-segment elevation in leads aVR and ST depression in the inferior leads.5 Lead aVR also helps in differentiating between LMCA and proximal Left Anterior Descending artery(LAD) disease. ST elevation in aVR more than in V1 is suggestive of LMCA disease and vice versa is suggestive of proximal LAD disease.6 Coronary artery disease (CAD) is the world’s leading cause of mortality.7 Treadmill testing (TMT) is the most widely used and widely available method for investigating the presence of CAD. The TMT is used to determine the likelihood of CAD, to determine functional capacity and to assess the effects of therapy. The TMT may also be used to assess the likelihood of anatomic severe disease that may be of prognostic importance.8 During TMT, the ST-segment and T wave changes, arrhythmias and decreases in blood pressure may indicate myocardial ischaemia. The ST-segment elevation in leads reflecting the ischaemic region of the heart demonstrate significant stenosis in the coronary artery supplying this region. The lead aVR is infrequently used in clinical practice. Because it is the reciprocal lead of the basal interventricular septum, aVR is affected by the perfusion changes of this region.9 Likewise,Engelen et al,6 reported that ST elevation at the lead aVR during the acute phase of anterior myocardial infarction (MI)indicates left anterior descending artery (LAD) occlusion before the first septal branch. Other studies have also revealed that ST segment elevation in lead aVR may identify patients with the left main coronary artery (LMCA);10,11 that ST segment depression at aVR is a sign of reduced (35%)ejection fraction;12 and that ST segment elevation in aVR is associated with increased in-hospital mortality rates among non ST elevation MI patients.9