ECG (electrocardiogram; also EKG) and diagnosis

“Characteristic ECG findings for the diagnostic entities of atrial fibrillation or of heart block were described in the ECG’s first decade. However, the ECG findings were not essential to the definition; both fibrillation and heart block had already been clinically described. In the early twentieth century, ECG users created their first unique diagnostic role in the diagnosis of myocardial infarction. Coronary artery disease was rarely diagnosed during life before 1918, although it was frequently described at autopsy. However, premortem diagnosis of the coronary disease increased dramatically following James Herrick’s 1918 description of particular ECG changes in myocardial infarction. The disease of myocardial infarction had become defined, in part, by ECG changes. Yet even at an elite hospital such as the MGH, the ECG was not a routine test for patients with suspected infarction as late as 1935. By 1940, however, long discussions about the diagnostic efficacy of the ECG tracing are found in the case records of patients presenting with chest pain. By around 1950, the ECG had become routinely used, as it is today, in the diagnostic evaluation of patients critically ill for whatever reason” (Howell IV, 285).