Longitudinal Changes in QTc Interval in Cancer Patients After the Initiation of Systemic Therapy: Analysis of the ONCOECHO Study Cohort.

Background/

Objectives

Anticancer therapies are associated with a prolongation of QT interval of electrocardiogram (ECG), increasing the risk of arrhythmias. To evaluate this risk in cardiovascular disease-free subjects with cancer, ECG recorded at baseline, months 3, 6 and 12 from 291 participants from the ONCOECHO database were analyzed.

Methods

Both Fridericia (QTcF), considered as standard, and Bazett (QTcB) formulas were used to calculate corrected QT (QTc).

Results

The study cohort consisted of 61.8% subjects with breast cancer, 26.5% with hematologic malignancies, 7.3% with colorectal cancer and 4.4% of patients with kidney cancer. At baseline, six patients had a QTcF ≥ 460 ms and one ≥ 500 ms. QTcF values differed significantly across time points (p = 0.0125), with a significant increase between baseline and month 6 (400.9 ± 29 ms vs. 409.6 ± 25 ms, p = 0.0075). Use of the Bazett formula resulted in 5.49 (95% CI 3.28-9.19) higher odds of identification of QTc ≥ 460 ms than with the Fridericia rule. A LASSO logistic regression model identified age, QTcF at baseline and month 3 to increase odds of QTcF ≥ 460 ms, whereas higher ejection fraction was associated with decreased odds.

Conclusions

Analysis shows that cancer patients receiving cardiotoxic therapy are at relatively low risk of QTc prolongation, but choosing the appropriate QTc correction formula is essential.