ECG Interpretation in Transmen

Evidence-Based Approach by Duration of Therapy

The Multinational Association of Supportive Care in Cancer guidelines state that QTc is influenced by gender-affirming hormone therapy (GAHT), and after 12 months of therapy, values should be interpreted within the reference range for the affirmed gender, according to the American Cancer Society 1, 2
For transmen on testosterone therapy for ≥12 months, ECG parameters including QTc intervals should be interpreted using male reference ranges, as testosterone therapy causes electrocardiographic changes that trend toward the affirmed gender, as recommended by the Multinational Association of Supportive Care in Cancer 1, 2
Interpret ECG values in the context of type, dose, and duration of GAHT, recognizing that values are transitioning, for transmen on testosterone therapy for <12 months, as suggested by the Multinational Association of Supportive Care in Cancer 1, 2
Use female (sex assigned at birth) reference ranges for transmen who stopped testosterone therapy ≥3 months, according to the Multinational Association of Supportive Care in Cancer 1, 2

The upper limit of normal for QTc intervals is 450 ms for men, which applies to transmen on testosterone therapy ≥12 months, as stated by the American Heart Association in Circulation 3
The upper limit of normal for QTc intervals is 460 ms for women, which applies to transmen off testosterone therapy ≥3 months, as stated by the American Heart Association in Circulation 3
For men, including transmen on testosterone ≥12 months, the ST-segment elevation thresholds are V2-V3: 0.2 mV (2 mm) if ≥40 years old; 0.25 mV (2.5 mm) if <40 years old, and all other leads: 0.1 mV (1 mm), as recommended by the American Heart Association in Circulation 4
For women, including transmen off testosterone ≥3 months, the ST-segment elevation thresholds are V2-V3: 0.15 mV (1.5 mm), and all other leads: 0.1 mV (1 mm), as recommended by the American Heart Association in Circulation 4

Red blood cell indices, which affect cardiac parameters, stabilize within 6 months of testosterone initiation and reach male reference ranges within 3 months, as reported by the Multinational Association of Supportive Care in Cancer and the American Cancer Society 1, 5
Hemoglobin increases to male reference range within 3 months, affecting oxygen-carrying capacity and potentially cardiac electrical properties, as reported by the American Cancer Society and the American College of Cardiology 5, 6

Using female reference ranges after 12 months of testosterone therapy could lead to false-positive diagnoses of QTc prolongation, as warned by the Multinational Association of Supportive Care in Cancer and the American Cancer Society 1, 2
Male QTc intervals are physiologically shorter than female intervals due to testosterone effects, as stated by the American Heart Association in Circulation 3
When evaluating for acute myocardial infarction, use the appropriate gender-specific ST-elevation thresholds based on duration of testosterone therapy, as recommended by the American College of Cardiology in the Journal of the American College of Cardiology 4
Misapplication of female thresholds in a transman on long-term testosterone could delay recognition of STEMI, as warned by the American College of Cardiology in the Journal of the American College of Cardiology 4

Determine testosterone therapy duration and apply the corresponding reference ranges, as suggested by the Multinational Association of Supportive Care in Cancer and the American Cancer Society 1, 2, 5
Apply gender-specific thresholds for QTc prolongation assessment, ST-elevation in acute coronary syndrome evaluation, and normal variant early repolarization patterns, as recommended by the American College of Cardiology in the Journal of the American College of Cardiology and the American Heart Association in Circulation 4, 5, 8