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Decisions on the use of antiarrhythmic drugs or device therapy (cardioverter defibrillators, catheter ablation) should consider life expectancy, quality of life, and complication risks.349 Most cancer therapy-induced VA are related to a prolongation of QTc leading to the development of TdP.259,516,542 Risk factors for QTc prolongation and TdP are summarized in Table 8.4,22,45,48,516,543 The upper 99% limits of normal for QTc values in the general population are 450 ms for men and 460 ms for women.545 Although there is no threshold of QTc prolongation at which TdP can occur, a QTc ≥500 ms is associated with a two- to three-fold higher risk for TdP, while TdP rarely occurs when QTc is ,500 ms.442 Although the incidence of QTc prolongation ≥500 ms and TdP is low during cancer therapy, QTc prolongation to levels that require closer monitoring (QTc ≥480 ms) is more common (Table 9).4,9,22,45,48,49,259,369,516,543,546 Changes in the QT interval of .60 ms from baseline should not routinely affect treatment decisions if the QTc remains ,500 ms.1 Cardiology consultation is advised in patients with an abnormal baseline QTc interval, patients treated with drugs that prolong the QT interval, those who develop new cardiac symptoms (syncope or pre-syncope, rapid palpitations or QTc prolongation with new-onset bradycardia, high degree of heart block), and/or those with known inherited arrhythmia

QTcF value

QTcF value

QTcF value

QTcF monitoring according to drugspecific protocol

ECG after any dose increase of QTc-

prolonging drug

(class I)

If QTcF <500 ms Continue treatment at same or

reduced dose according to

drug-specific protocol

(Class I) Consider alternative

treatment Alternative

treatment

(Class I) (Class I) (Class I) QTcF value

Resume treatment at the same

or reduced dose according to drug-specific protocol Consider restarting treatment

at reduced dose

(Class IIb) MDT to discuss alternative

cancer treatments

(Class I)

≤480 ms

≤480 ms

≤480 ms >480 ms

>480 ms and

<500 ms

>480 ms and

<500 ms >480 ms and

<500 ms ≥500 ms

≥500 ms ≥500 ms TdP or sustainedVA

Correct baseline risk factors for QTc prolongationb Avoid/stop concomitant QTc prolonging drugsb Ensure K+ >4.0 mmol/L, Mg2+ >2.0 mg/dL (>1.10 mmol/L) and normal values of corrected Ca2+

Baseline 12-lead ECG: QTcF

Start therapy ECG monitoringc Cardio-oncology evaluation Correct reversible causesb

Correct reversible causesb Weekly ECG monitoring Drug interruption Correct reversible causesb

Drug withhold Correct reversible causesb

QTc monitoring before and duringtreatment withQTc prolonginganticancerdrugsa

Figure 32 Corrected QT interval monitoring before and during treatment with corrected QT interval-prolonging anticancer drugs. Ca2+ , calcium; ECG, electrocardiogram; K+, potassium; MDT, multidisciplinary team; Mg2+, magnesium; QTc, corrected QT interval; QTcF, corrected QT interval using Fridericia correction; TdP, Torsade de pointes; VA, ventricular arrhythmias. QT interval using Fridericia correction (QTcF = QT/3√RR) is recommended in patients with cancer. Upper 99% limits of normal for QTc values in the general population are 450 ms for men and 460 ms for women.369 aTable 9. bTable 8 and https://www.crediblemeds.org. cECG monitoring at baseline, once steady-state anticancer drug levels have been achieved, after each dose modification, or any treatment interruption .2 weeks; monthly for the first 3 months, and then periodically during treatment depending on patient-specific risk factors and cancer treatment. Downloaded from academic.oup.com/eurheartj/article/43/41/4229/6673995 by guest on 07 October 2026