Stress nuclear imaging was also performed at the end of 6 hours of observation instead of graded exercise stress testing alone. There will be a significant proportion of patients who will not be eligible for standard exercise treadmill stress test due to poor exercise tolerance. Even for those who underwent exercise testing, studies showed that 24.2% were inconclusive because of baseline ECG abnormalities (left ventricular hypertrophy, left bundle-branch block or patient on digoxin). Some patients may not be able to achieve the required exercise level.