Grade 1: average QTc 450 - 480 ms
Grade 2: average QTc 481 - 500 ms
Grade 3: Average QTc ≥ 501 ms; > 60 ms change from baseline
Grade 4: Torsade de pointes; polymorphic ventricular tachycardia; signs/symptoms of serious arrhythmia
Reference: Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0 Published: November 27, 2017
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