Abnormal ECG in Melanoma: Meaning, causes, and when to worry

An abnormal ECG (electrocardiogram) in someone with melanoma can have several possible explanations, and the level of concern depends on the pattern found, your symptoms, and whether you’re receiving certain melanoma treatments that can affect the heart. Many ECG changes are minor and reversible, but some can signal risks like rhythm problems, heart strain, or inflammation, so it’s wise to review them with your oncology and cardiology team.

Why ECGs can be abnormal

• Treatment-related effects (common): Several modern melanoma therapies can alter heart rhythm or function. BRAF inhibitors (dabrafenib, vemurafenib, encorafenib) and MEK inhibitors (trametinib, cobimetinib, binimetinib) can prolong the QT interval on ECG, which increases the risk of abnormal heart rhythms. ^{[1] [2]} These medicines often require baseline and periodic ECG monitoring, especially if you have other risk factors like electrolyte imbalances. ^{[3] [4]}
• Immune therapy effects (less common but important): Immune checkpoint inhibitors (e.g., nivolumab, ipilimumab) can rarely cause myocarditis (heart inflammation), which may show up as ECG changes, chest pain, shortness of breath, or palpitations. Some centers obtain baseline ECG and may check troponin during early treatment because early detection matters, although practices vary. ^{[5] [6]}
• Baseline or unrelated causes: Even before treatment, ECG abnormalities can be seen and are often nonspecific; in cancer populations, a notable percentage develop ECG changes that are usually not symptomatic and may not require intervention. ^{[7] [8]}
• Rarely, cardiac metastasis: Melanoma can metastasize to the heart, and cardiac involvement can produce ECG changes or even mimic heart attacks; this is uncommon but recognized. [PM14]

Which ECG changes are linked to melanoma therapies

• QT interval prolongation: This is a lengthening of the heart’s electrical recovery time and can predispose to dangerous rhythms if marked. Therapies like dabrafenib, encorafenib, and vemurafenib can prolong QT, and treatment may be paused or adjusted if QTc reaches concerning levels (e.g., ≥500 ms). ^{[9] [10] [11]}
• Left ventricular (LV) dysfunction: MEK inhibitors can reduce ejection fraction (EF) in a small proportion of people; monitoring with echocardiogram may be considered for higher‑risk individuals. ^{[12] [13]}
• Arrhythmias and blood pressure effects: BRAF/MEK combinations have been associated with atrial fibrillation, bradyarrhythmias, hypertension, and other cardiovascular events, warranting comprehensive cardiac monitoring in high‑risk patients. [PM23] [PM26]

When to be concerned

• Higher concern:
  • QTc ≥500 ms, large new QT changes, or new significant arrhythmias. Starting or continuing certain BRAF therapies is generally avoided if QTc is ≥500 ms, and risk factors like low electrolytes should be corrected. ^{[10] [11]}
  • New chest pain, shortness of breath, fainting, rapid or irregular heartbeat, or unexplained fatigue these can suggest myocarditis or a serious rhythm problem and need urgent evaluation. ^[6]
• Lower concern:
  • Minor nonspecific ECG changes without symptoms, especially if you’re not on cardiac‑affecting therapies, are often monitored without immediate intervention. ^{[7] [8]}

Practical next steps

• Ask which ECG change was detected. QT prolongation, ST/T‑wave changes, or conduction abnormalities have different implications. If QT is prolonged, your team may check and correct electrolytes (potassium, magnesium, calcium), review other QT‑prolonging medications, and repeat the ECG. ^{[3] [4]}
• Share symptoms promptly. Report chest pain, dyspnea, palpitations, dizziness, or syncope right away, particularly if you are on immune therapies or BRAF/MEK inhibitors. ^[6]
• Baseline and periodic monitoring. If you are receiving BRAF/MEK inhibitors, ECG monitoring at baseline and as clinically indicated is typically recommended, and echocardiograms may be considered for those at higher risk of heart failure. ^{[12] [4]}
• Team approach. A cardiology review is often advised when ECG changes occur during melanoma therapy, and dose changes or treatment pauses may be needed to protect heart health while maintaining cancer control. ^{[14] [13]}

Summary

Abnormal ECG results in melanoma can range from benign, treatment‑related changes to signals of more serious heart issues. The most common treatment‑linked finding is QT prolongation with BRAF/MEK inhibitors, which is usually manageable with monitoring and adjustments, while immune therapies rarely cause myocarditis that requires prompt attention. ^{[1] [10] [6]} Working closely with your oncology team and cardiology when needed helps clarify the cause and guide safe, personalized care. ^{[14] [12]}