The information provided by you suggests that your father has no complaints of chest discomfort or shortness of breath etc. The heart function is normal but TMT shows an abnormality on exercise. In this setting there is no need for a panic, he needs further evaluation by tests which give more specific information. The test should be a stress echo or a stress thallium. In addition, tests for other risk factors like a complete lipid profile, blood sugar profile etc and periodic BP check are required and management of all the risk factors under supervision is required if there are any associated problems. Regular exercise is a good habit and always helps in the long run but problems can still occur and periodic assessment and health checks are directed to diagnose abnormalities before major problems occur. A TMT test can be false positive also especially in asymptomatic individuals.