Reading an ECG more complex than previously thought

Source – Vandana Kamath, Bangalore Mirror Bureau

Electrocardiogram (ECG), the basic reference tool of cardiologists, seems to have been rocked by an interpretation crisis.
Very often ECG is not the most accurate way of diagnosis of a heart attack and has to be coupled with many other tests to ensure that it is, in fact, a heart attack, which is usually done by specialists.
Senior cardiologist Dr CN Manjunath, director Jayadeva Institute of Cardiovascular Diseases says, “Usually, a majority of heart attacks cannot be diagnosed during the initial test of ECG. ECG changes could be delayed in many cases.
There are three arteries that carry blood to the heart. A blockage in any one of these can cause a heart attack. There is one particular artery that is behind the heart called the left circumflex artery. A blockage in this is not well represented in the ECG and is usually considered a blind spot.
There is a high index of suspicion here that needs to be determined by biomarkers. Most Type 2 heart attacks occurs with this ECG changes. There is need for repeated ECGs, angiogram and Echo in the first 12-24 hours after the patient has complained of chest pain during which time the patient must be kept under observation.
Often, because these heart attacks are not determined by ECG, they end up being fatal. A feeling of tightness or shortness of breath are often signs of heart attack and specialists say that a strategic approach to this becomes extremely important. In the West, a majority of heart attack deaths is due to wrong ECG diagnosis.
Dr Bharat Dubey, cardio thoracic surgeon, BGS Global Hospital says, “In an ECG, an elevation in the ST segment may indicate a myocardial infarction. If there is a non-ST elevation and the patient still complains of a chest pain, then a cardiac enzymes test that is a blood test may be accurate in determining if a person has had a heart attack or not.”
Blood tests for the biomarker troponin can detect myocardial infarctions in around 50 per cent of patients, doctors say. Dr Vivek Jawali, a senior cardiologist with Fortis Hospital says, “Unlike popular belief, detecting heart attack is a wholesome process. Apart from clinical shrewdness, complete observation for the first three hours is extremely important. Instead of a single test. there are multiple tests that need to be done to determine, if the person really has had a heart attack or not.”