Author + information
- 1Department of Cardiology, First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
- 2Beijing AnZhen Hospital, Capital Medical University, the Key Laboratory of Remodeling-Related Cardiovascular Diseases, Ministry of Education, Institute of Heart, Lung and Blood Vessel Diseases, Beijing, China
Recently we had reported the malignant cancer is one of the major contributors to all-cause mortality in acquired long QT syndrome (ALQTS) in hospitalized patients in China. This study aims to determine characteristics in ALQTS patients with malignant cancer showing a markedly prolonged QT interval.
Clinical follow-up was performed in both ALQTS group (QTc ≥ 500ms, n=150) and control group (QTc ≤ 440ms, n=293). The age, gender and cancer diagnosis between ALQTS and control group were comparable (p=NS). Clinical characteristics, ECG parameters, chemotherapy drugs or QT-prolonging medications, laboratory test results were also elucidated. The death of all causes occurred during hospital stay and after discharge was investigated in all study subjects. Cox regression and Kaplan-Meier survival analyses were performed to determine the effects of markedly prolonged QTc on all-cause mortality.
1) Follow up for 351±346 vs. 514±305 days, the ALQTS subjects with a markedly prolonged QTc (520±28 ms vs. 422±15 ms, p<0.0001) had a much higher all-cause mortality than the control group (63.3% vs. 33.4%, p<0.001).
2) More patients in the ALQTS group had a baseline condition of hypertension (29.3% vs. 16.4%, p < 0.05), infection (21.3% vs. 5.1%, p < 0.001), Hematologic diseases (12.0% vs. 1.4%, p < 0.001), hypokalemia (31.7% vs. 5.2%, p < 0.001), hypocalcemia (22.7% vs. 4.9%, p < 0.001) and QT-prolonging drugs (31.3% vs. 6.8%, p < 0.001).
3) After adjustments, odds ratio for chemotherapy drugs affected microtubulin was 1.995 (95%CI 1.225-3.228, p < 0.05).
4) Age (HR 1.02, 95%CI 1.00-1.04, p<0.05), Gastrointestinal diseases (HR 2.98, 95%CI 1.71-5.21, p<0.05), Renal failure (HR 7.49, 95%CI 2.38-23.56，p<0.05), Hypokalemia (HR 2.36, 95%CI 1.46-3.80, p<0.05), Antimicrotubule agents (HR 1.77，95%CI 1.02-3.09, p<0.05) are the major contributors to all-cause mortality in ALQTS.
Among malignant cancer patients, the all-cause mortality in patients with markedly prolonged QTc is significantly higher than those without QTc prolongation. It is overlooked by oncologists that QTc appears to prolong because of the complexity of diseases and medicines in the process of treatment. Measurement should be promptly taken between oncology and cardiology department to monitor and prevent ALQTS.