Figure 1.

T-wave alternans (TWA) and arrhythmogenesis.

A, TWA prevalence and arrhythmias in long QT syndrome (LQTS) patients.¹⁷ Left, TWA prevalence vs corrected QT interval (QTc). Right, Cardiac event rate vs QTc with (black) and without (white) TWA. B, TWA transitioning directly to Torsade de pointes (TdP) without a clear preceding premature ventricular complex (PVC).¹¹ C, TWA in which TdP is initiated by a PVC falling on the large T-wave of the alternating beats.²³ D, TWA, followed sometime later by TdP initiated by a short-long-short sequence.²⁴