Exact assessment of heart rhythm may improve chemotherapy use
Written By : Isra Zaman
Medically Reviewed By : Dr. Kamal Kant Kohli
Published On 2022-09-23 03:30 GMT | Update On 2022-09-23 03:30 GMT
Using the wrong mathematical formula to assess heartbeat rhythms may lead oncologists to inappropriately stop life-saving chemotherapy, according to research findings from UNC Lineberger Comprehensive Cancer Center scientists.
Standardizing the mathematical formulas for measuring heartbeat rhythms with electrocardiograms, and avoiding one commonly used formula, could reduce this unintended outcome, the researchers reported.
The formulas in this study are based on how the cardiac system recharges itself after each heartbeat. In reading an ECG, heartbeat spikes and bumps, called P through U waves, indicate when the heart is contracting and relaxing. The interval between the start of the Q wave and end of the T wave, when prolonged, is of most concern for people receiving chemotherapy.
When the heart muscle takes a comparatively longer time to contract and relax than usual, which is known as QT prolongation, it may increase the risk of developing abnormal heart rhythms that can lead to sudden cardiac arrest.
Because QT prolongation is a potentially serious side effect, every chemotherapy drug goes through rigorous testing for QT prolongation in its approval process.
In their study of different formulas, the researchers discovered that one formula, the Bazett formula, was associated with a three-fold increase in the corrected QT interval compared to other formulas used with oncology patients.
The researchers looked at medical records of 6,881 adult cancer patients who received 24 different types of chemotherapy between 2010 and 2020. The patients were seen at the North Carolina Basnight Cancer Hospital and received nearly 20,000 ECGs.
The investigators found that the Bazett formula resulted in longer QT prolongation periods than two other formulas (Framingham and Fridericia) in 40.9% of ECGs examined; this was concerning as Bazett is the default formula used with many ECG devices.
Reference:
Daniel R. Richardson et al,Association of QTc Formula With the Clinical Management of Patients With Cancer,JAMA Oncology, DOI: 10.1001/jamaoncol.2022.4194
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