Contrast medium (CM) is used to visualize the arterial lumen during coronary angiography (CAG). Contrast medium used during CAG cause temporary changes in cardiac function, including heart rate, blood pressure, coronary circulation, myocardial contractility, and peripheral resistance [1,2]. Contrast medium may cause changes in the electrophysiological properties of the myocardium, which may trigger some changes in the electrocardiography (ECG). These effects can be seen from heart rate change to the development of malignant arrhythmia [3,4]. An increase in the amount of contrast material used in angiographic procedures leads to an increased risk of adverse events, and it has been shown that increased contrast material volume is associated with increased mortality independent of the underlying cardiovascular disease [5]. As a result of studies carried out in recent years, safer, non-ionic, low osmolarity CMs have been developed instead of ionic high osmolarity CMs, which have serious side-effect profiles. Although low osmolality nonionic contrast agents cause less ECG changes than conventional high osmolality agents, there are studies showing their significant effects on cardiac electrophysiology [[6], [7], [8]].

The frontal plane QRS-T (fQRS-T) angle is expressed as the absolute angular difference between the QRS and T wave axes. The fQRS-T angle is an indicator of ventricular repolarization heterogeneity [9]. Increased ventricular repolarization heterogeneity is associated with increased arrhythmia frequency. A wide fQRS-T angle is associated with an increased risk of cardiovascular and arrhythmic events and higher mortality [10,11]. In our study, the effect of contrast medium on cardiac electrophysiology will be investigated by using fQRS-T angle.