QRS Complex and Repolarization Abnormalities

Abnormalities of the QRS complex and repolarization are frequently encountered on ECG, with their causes being myriad. Stigmata of left or right ventricular hypertrophy (LVH and RVH, respectively) are oftentimes identified by new learners, but findings such as electrical alternans may be more elusive to less-experienced ECG readers. This text aims to inform all readers about QRS complex and repolarization abnormalities, whether they be overt or covert in nature. Moreover, by visualizing non-specific changes to the ST segment, secondary repolarization changes from hypertrophy, a prolonged QTc interval, and other abnormalities, these abnormalities that often go unnoticed will jump off the page. Indeed, repolarization abnormalities seem to lack the “star power” of high-yield topics like myocardial infarction and ventricular arrhythmias. Nevertheless, recognizing repolarization abnormalities and QRS complex pathology are essential components to a thorough, complete ECG interpretation. For example, the scenario given above regarding electrical alternans may be subtle on ECG; however, a speedy identification of this finding may expedite an echocardiogram and facilitate the early diagnosis of cardiac tamponade. When it comes to abnormalities of the QRS complex and repolarization, one cannot underestimate the power of their clinical value.