Abstract & Commentary
Risk of Early Repolarization ECG Patterns
By Michael H. Crawford, MD, Editor
Source: Muramoto D, et al. Patterns and prognosis of all components of the J-wave pattern in multiethnic athletes and ambulatory patients. Am Heart J 2014;167:259-266.
ECG early repolarization patterns were long thought to be benign normal variants until recent papers purported to show a relationship between these patterns and the risk of malignant arrhythmias and cardiac death. Since these patterns are common in young athletes, concern has arisen about their interpretation. Thus, these investigators from Stanford University performed a retrospective study of more than 5000 consecutive ECGs performed at a Veterans Affairs hospital between 1997-1999. They excluded patients with atrial fibrillation or flutter, QRS duration > 120 msec, paced rhythm, pre-excitation, or acute myocardial infarction. Also, routine screening ECGs of Stanford athletes were recorded in 2007-2008. There were 4041 patient ECGs (90% male, average age of 57 years), and there were 1114 athlete ECGs (57% male, average age 19 years). Rather than using the ambiguous term "early repolarization" they preferred the term "J-wave pattern," which included elevation of the QRS-T junction of at least 0.1 mV from baseline in the inferior or lateral leads manifested as terminal QRS slurring or notching of the R or S wave downstroke, respectively. The notching was termed a J-wave. The primary outcome was time to cardiovascular death in the patients; the athletes had no cardiovascular events after 3 years.
ST elevation was more common in the lateral vs inferior leads in both groups: patients 4.8% lateral vs 1.0% inferior; athletes 21 vs 1.3%, respectively. J-waves were equally present in lateral and inferior leads and were < 5% of both groups. Terminal QRS slurring was more common in the inferior leads in both groups: inferior < 10% and lateral < 5% of both groups. The presence of J-wave patterns in both lead groups was infrequent in both populations (2.4% of patients, 5.5% of athletes). Most of the components of the J-wave pattern were more frequent in men. All components of the J-wave pattern in the lateral leads were more frequent in African American patients and athletes. No single component or combination of the J-wave patterns was associated with an increase in cardiovascular death. The authors concluded that their large, multiethnic, ambulatory population J-wave patterns were not predictive of cardiovascular outcomes and that their high prevalence, especially in men and athletes, would make them poor screening parameters even if they were predictive.
Commentary
A few years ago, Haissaguerre and later Nam described cases of young men with J-waves and unprovoked ventricular fibrillation (VF). This rare syndrome is of unknown etiology as it does not fit into the usual channelopathies. This created a "fear of J-waves" that has created considerable controversy.1 Also, other prior reports have suggested that the early repolarization pattern, especially if confined to the inferior leads, is associated with higher rates of cardiovascular events and death. This study refutes these assertions in a large multiethnic population with long-term follow-up. Also, they analyzed all components of the J-wave pattern, not just ST elevation or J-waves. Some prior studies used selective criteria for the early repolarization pattern, but the main weakness of prior studies is selection biases. Also, some studies had very long follow-up periods, up to 30 years. It is difficult clinically to deal with a death 20 years after an ECG is done.
Their analysis of an athlete population showed that these J-wave patterns are prevalent (5-20%). So, even if a J-wave identifies subjects at risk for a rare genetic disorder associated with VF (high sensitivity), the specificity is horrible. You can't put an ICD in even 5% of athletes or exclude them from sports participation. Despite this flurry in the literature over the last decade, currently we should view these J-wave patterns or early repolarization as largely benign entities again and remove them as triggers for further evaluation.
REFERENCE
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Viskin S. Idiopathic ventricular fibrillation "Le Syndrome d'Haïssaguerre" and the fear of J waves.J Am Coll Cardiol 2009;53:620-622.
