The role of HIV Viral Load and CD4+ Cell Count in the prolongation of the QT interval in patients from an HIV outpatient clinic

Background: QTc Interval prolongation is associated with life-threatening arrhythmias and it has been reported to occur more frequently in the HIV-infected population. Methods: The data was collected from the charts of a cohort of 135 consecutive HIV-infected patients from our HIV outpatient clinic. QTc interval was corrected to the heart rate using Bazzets formula .The cohort was divided into two groups(prolonged QTc and normal QTc interval). QTc interval was considered prolonged if it was >440ms in males and >460ms in females. Multiple variables and potential risk factors were collected including the CD4+ cell count and Viral Load (VL) measurements which were done at the same day or within few days from the time the ECG was done. Results: 23 patients were found to have prolonged QTc (17%).No significant difference between the groups was observed for any baseline characterestics;however stastistically significant differences were observed with regard to the CD4+ cell count and VL. The ROC curves for both CD4 count and VL were obtained to establish cut-off points .The cutoff points for CD4 count and VL were 144 and 17.9 x 103 respectively. Sixteen of 23 subjects (70%) with prolonged QTc had CD4+ cell counts < 144 cells/mm3 as opposed to only 27 of 112 (24%) of subjects with normal QTc interval (OR: 7.20; 95% CI: 2.88 to 19.33; p < 0.0001). For VL, 18 of 23 subjects (78%) with prolonged QTc had levels ≥17.9× 103 copies/ml, whereas 43 of 105 (41%) of patients with normal QTc had VL greater than the cut-off value (OR: 5.19; 95% CI: 1.79 to 15.05; p = 0.002). The simultaneous presence of both risk factors increased the OR to 14.74 (95% CI: 3.84 to 56.55; p < 0.0001). Conclusion: Our study confirmed that the risk of QTc prolongation increases with the progression of the HIV infection. Low CD4 cell count and high Viral load could be considered as independent potential risk factors for QT prolongation in HIV patients in the outpatientclinic settings.