A quick diagnosis of heart attack is important for speeding up treatment of patients in emergency rooms. Pickering and colleagues review a new method that can detect heart damage at very low levels, and can be used to speed up diagnosis.
Heart attack is a leading cause of death throughout the world. Although this condition is highly treatable, it must be diagnosed quickly. As a result, many people who are experiencing the early symptoms of a heart attack go to the emergency room, but only 10-20% of these patients actually are having a heart attack. A quick diagnosis in emergency rooms also allows the safe discharge of patients who are not having heart attacks, freeing up valuable resources for other patients.
In the Annals of Internal Medicine, Pickering and colleagues investigated the effectiveness of a new method of diagnosing heart attacks in emergency room patients. This method, hs-cTnT, measures the blood concentration of troponin T, a protein that is released when heart tissue is damaged. If troponin T is too low to be detected, doctors can rule out heart attack as a cause of patient symptoms. Pickering and colleagues used existing data from a series of small clinical studies to determine whether hs-cTnT results were an accurate predictor of patient outcomes and subsequent heart attack risk. The final analysis includes a total of 9241 patients from 11 separate studies performed in Europe, Australia, and New Zealand.
They report that the hs-CTnT method is more sensitive than other methods for measuring blood troponin T levels, with a confidence interval between 95.5% to 99.8% sensitivity. In combination with echocardiogram (EKG or ECG) data, which measures the electrical activity of the heart, hs-cTnT can provide a quick diagnosis of heart attack.
Although the hs-cTnT method appears promising, limitation of the study must be kept in mind. The studies that Pickering and colleagues used to perform their analysis did not represent unbiased samples. One of these studies had a younger, lower-risk cohort, in which hs-cTnT may not be as effective for quickly diagnosis or ruling out heart attack. Further, doctors must wait at least three hours after the onset of symptoms in patients before testing for troponin in the blood, to avoid the risk of obtaining false negative results. Finally, hs-cTnT measurements are calibrated by batch, and cannot be directly compared across studies.
Written By: C.I. Villamil