T-wave reversal in the augmented unipolar right arm electrocardiographic lead is associated with increased risk of sudden death

Background: Repolarization abnormalities are associated with ventricular arrhythmias, and published studies report that a reversal of T wave polarity (positive or flat T wave) in lead aVR may be linked to increased cardiovascular mortality. We evaluated whether a positive or flat T wave in aVR is a risk marker for sudden cardiac death (SCD). Methods: SCD cases from the Oregon Sudden Unexpected Death Study (catchment population ~1 million) were compared to geographic controls with coronary artery disease and no history of SCD. Archived electrocardiograms performed prior and unrelated to the SCD event were evaluated. Results: SCD cases (n = 691, 67.6 ± 14.9 years, 69 % male) were more likely than controls (n = 663, 66.2 ± 11.6 years, 67 % male) to have diabetes (40 vs 32 %; p < 0.01), left ventricular ejection fraction (LVEF) ≤35 % (27 vs 11 %; p < 0.01), prolonged QTc (≥450 ms; 54 vs 28 %; p < 0.01) and positive (19 vs 13 %; p < 0.01) or flat T wave (14 vs 7 %; p < 0.01) in aVR. On multivariable analysis, a positive/flat T wave in aVR was independently associated with SCD (OR 1.9, 95 % CI 1.3–2.8, p < 0.01). However, a positive T wave alone lost statistical significance in patients with LVEF ≤ 35 % and QTc ≥ 450 ms. In a subgroup analysis among patients with normal LVEF, QTc, and no diabetes, a positive T wave in aVR (but not a flat T wave) remained associated with SCD (OR 2.8, 95 % CI 1.2–6.1, p < 0.01). Conclusions: A positive or flat T wave in lead aVR was associated with SCD in subsets of patients. This simple ECG marker in this often-ignored lead may contribute to enhancement of SCD risk stratification, and warrants further evaluation.