Cardiologie clinique et expérimentale
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Frequency and Associated Factors with QT Interval Prolongation in Adults with Chronic Heart Failure in Yaoundé

Jerome Boombhi*, Barnabe NicolasTonyeTonye, Chris-Nadege Nganou-Gnindjo, Vicky AmaMoor, Faustin Ulrich Nzounji, Mazou N. Temgoua, Alain Menanga, Samuel Kingue

Background: Heart failure is a chronic cardiovascular disease that has an increasing incidence and a poor prognosis in adults in Sub-Saharan Africa due to the rhythm disorders frequently associated to it. Although QT interval prolongation increases cardiovascular mortality in chronic heart failure, there is poor knowledge and it remains undiagnosed... in Sub-Saharan Africa. We therefore deemed it appropriate to determine the frequency and identify the factors associated with QT interval prolongation in adult patients with chronic heart failure in Yaoundé. Our main objective was to study the frequency and factors associated with QT interval prolongation in adult patients with chronic heart failure in Yaoundé-Cameroon.

Objective: The objective of our study was to study the frequency and factors associated with QT interval prolongation in adults with chronic heart failure in Yaoundé.

Methods: We conducted a descriptive cross-sectional study from January to May 2020 (05 months) at the Central Hospital and General Hospital of Yaoundé.  Adults with chronic heart failure presenting in these two hospitals without signs of décompensation were recruited on an outpatient basis. A 12-lead electrocardiogram was performed to all these patients to determine the type of heart rhythm, measure the QT interval, look for rhythm disturbances and hypertrophy indices (ventricular and atrial). For heart rates between 60 and 100 beats per minute, Bazett's formula was used for the calculation of the corrected QT; for heart rates outside this range, Framingham's formula was used. Patients' left ventricular systolic and diastolic functions were assessed by transthoracic echocardiography (TTE). Blood measurements of creatinine, urea, potassium, sodium and total calcium were performed. The significance level was set at 5%.

Results: Out Of 104 patients, 19 (18.27%) had a prolonged QT interval and 01 (0.09%) had an abnormally high QTc interval (>500 ms). Secondary repolarization disorders (p=0.035), hypocalcaemia (p=0.015), hypokalemia (p=0.0016), left ventricular hypertrophy (p=0.005), and plasma creatinine level>13mg/l (p=0.010) were associated with QT interval prolongation. QT prolongation was not significantly associated with advanced age or sex. No association was found between QT prolongation and heart failure drugs.

Conclusion: QT interval prolongation was present in 1/5 of our patients. The associated factors found were: hypokalemia, hypocalcaemia, a plasma creatinine concentration higher than 13mg/l, left ventricular hypertrophy and secondary repolarization disorders.