Prediction of Angiographic Extent of Coronary Artery Disease on the Basis of Clinical Risk Scores in Patients of Unstable Angina

Unstable angina and Non ST elevation acute myocardial infarction patients account for approximately 2 million to 2.5 million hospital admissions annually worldwide [1].The high risk unstable angina patients are at risk for death, myocardial infarction or recurrent ischemic events [2,3].Angiography clearly predicts Major Adverse Cardiovascular Events (MACE) in unstable angina and helps in deciding revascularization [4].Angiography is advisable only in high risk group who have more probability of significant coronary artery disease.Clinical predictors like duration of chest pain, age, cardiac biomarker positivity, ST segment depression in ECG, Congestive Heart Failure (CHF) -help in predicting high risk group.Similarly, clinical risk scores -Thrombolysis in Myocardial Infarction (TIMI) score, Platelet Glycoprotein IIb-IIIa in Unstable Angina, Receptor Suppression Using Integrilin Therapy (PURSUIT) score and Global Registry of Acute Coronary Events (GRACE) scores have established role in risk stratification and predicting prognosis [5,6]. AIM OF StudYTo determine the correlation of TIMI, PURSUIT and GRACE risk scores with angiographic extent of coronary artery disease and to predict the angiographic severity on the basis of various independent clinical predictors (age, ECG changes, cardiac biomarker positivity, etc). MAtErIALS And MEtHOdSThis hospital based single centre, cross-sectional, observational, descriptive study conducted at a tertiary care teaching institute.One hundred and sixty patients were recorded between April 2012 and November 2013.Study patients comprised patients presenting with unstable angina with most recent episode occurring within 72 hours of admission.Unstable angina was defined as angina or its equivalent with atleast one of the 3 features: occurring at rest or minimal exertions & usually lasting >20 minute, being severe, or occurring with a crescendo pattern (more severe, prolonged, or frequent than previous) [7].Patients with >72 hours since chest pain, or those with previous MI, Percutaneous Transluminal Coronary Angioplasty (PTCA) or Coronary Artery Bypass Grafting (CABG) or contraindications to coronary angiography were excluded.Patients with unstable angina who had evidence of myocardial necrosis on the basis of elevated cardiac serum markers such as Troponin T or I or Creatine Kinase-Muscle Brain (CK-MB) enzyme were diagnosed as Non-ST Elevation Myocardial Infarction (NSEMI).Informed consent was taken from each patient.Institutional Ethical committee reviewed the study and cleared it.All patients were assessed by use of a structured questionnaire regarding main risk factors and medical history.All patients underwent a detailed examination, 12 lead surface ECG, standard biochemical tests including lipid profile, cardiac serum markers and two dimentional echocardiography.Following 9 clinical risk predictors were recorded -Pain lasting for > 20 minutes, presence of 3 or more risk factors, presence of 2 or more episodes of pain in prior 24 hour, use of Aspirin within prior week, ECG finding of ST deviation of >=0.5 mm, ECG finding of T-wave inversion >=3 mm, Age >= 65 years, presence of elevated cardiac enzymes and presence of CHF in acute unstable angina cases.TIMI, GRACE & PURSUIT Scores were calculated based on history, vital parameters, lab investigations & ECG.