Global Heart Attack Diagnosis Redefined, Affecting Israeli ERs
Leading global cardiology organizations have introduced a "fifth universal definition of myocardial infarction," replacing the previous numerical classification with three distinct clinical categories based on the cause of the heart attack. This update aims to provide a more precise understanding of what triggers an event, enabling tailored diagnosis and treatment. The new definition was published by the European Society of Cardiology (ESC), the American College of Cardiology (ACC), the American Heart Association (AHA), and the World Heart Federation (WHF).
The revised classification distinguishes between primary myocardial infarction, caused by acute issues in the coronary arteries like plaque rupture and blood clot formation; secondary myocardial infarction, resulting from insufficient oxygen supply to the heart due to other acute medical conditions such as severe anemia or significant arrhythmias; and procedure-related infarction, a complication of invasive cardiac procedures or surgery.
A key clarification concerns troponin, a protein released into the blood when heart muscle is damaged. Elevated troponin levels alone are no longer sufficient to diagnose a heart attack. The new definition requires evidence of acute heart muscle injury alongside evidence of ischemia, or reduced blood flow. This broader approach accounts for troponin increases in conditions other than heart attacks, like heart failure or pulmonary embolism.
Significantly, the update addresses gender differences, recommending sex-specific troponin thresholds. This is because healthy women generally have lower troponin levels than men, and a uniform threshold could lead to underdiagnosis in women. The new guidelines also highlight heart attacks not caused by classic artery blockages, such as spontaneous coronary artery dissection (SCAD) or artery spasms, emphasizing the need for imaging and functional tests to identify these mechanisms.
While this international consensus does not immediately change Israeli emergency room protocols, the Israeli Cardiology Association participated in the document's review. The change is expected to lead to more precise diagnoses in Israel, differentiating between various causes of heart muscle damage, which can influence subsequent tests, treatments, and follow-up care. The core message is that a "heart attack" is not a single entity, and understanding its specific cause improves diagnostic and therapeutic accuracy.
