QTc prolongation in Black diabetic subjects with cardiac autonomic neuropathy.

Ogba J Ukpabi1, Basden JC Onwubere2
1. Federal Medical Centre, Umuahia, Nigeria.
2. University of Nigeria Teaching Hospital, Ituku Ozalla, Enugu, Nigeria.

Abstract
Background: Prolonged corrected QT (QTc) has been identifed as a risk factor for malignant arrhythmias and sudden cardiac
death. Caucasian studies have shown a defnite relationship between QTc prolongation and Cardiac Autonomic Neuropathy (CAN) in diabetic subjects.

Objective: To determine the prevalence of prolonged QTc in Black diabetic individuals with CAN and to ascertain how prolonged QTc correlated with the severity of CAN among these patients.

Methods: A total of 176 adult diabetic subjects were studied, 87 males and 89 females. There was a control group of non-diabetic individuals. Cardiac autonomic function was assessed using fve cardiovascular autonomic function tests. CAN was diagnosed if 2 or more of these tests were abnormal. Severity of CAN was determined according to the number of abnormal tests. QTc > 0.440 was regarded as prolonged.

Results: Fifty-one out of the 176 diabetic subjects (29%) had CAN. The prevalence of prolonged QTc in diabetic subjects with
CAN was 12%. QTc was prolonged in 1.6% and 0.6% of diabetic individuals without CAN and controls respectively. Although
QTc correlated strongly with cardiac autonomic function neuropathy, there was no defnite relationship between QTc prolongation and severity of CAN.

Conclusion: This study in a Black population is in agreement with the well-known relationship between QTc prolongation and CAN reported in Caucasian studies. In view of the wide variability of QTc in this study population, it is suggested that relative QTc increase may be a better indicator of CAN than a defnite QTc prolongation of greater than 0.440.

Keywords: QTc prolongation, Cardiac Autonomic Neuropathy, Black diabetics, sudden cardiac death.