Introduction:
ST depression in ECG trace is classically used to assess the cardiac ischaemia. Several other causes of ST depression, like hypokalaemia, digoxin therapy, left ventricular hypertrophy, left bundle branch block can be easily excluded. Sometimes the ST segment depression during tachycardia is observed in young healthy people where ischemic background is rare.
Case Report:
We present the case of an asymptomatic and without cardiovascular risk factors 29-years-old man who performed, during occasional sport visit, an ECG showing sinus tachycardia with diffuse ST segment depression. The ECG obtained at the presentation in Emergency Department of our hospital confirmed sinus tachycardia at 140 beats per minute and diffuse ST segment depression. This finding persisted during the following six hours and slowly regressed with normalization of the heart rate. The same ECG alteration was founded during an exercise test when the heart rate rised up to 90 bpm. A coronary angiography showed anatomically normal and angiographically free of stenosis coronaries ; the functional study, using Fractional Flow Reserve (FFR), Coronary Flow Reserve (CFR) and Index of Microcirculatory Resistance (IMR), currently gold standard for the functional study of microcirculation, was normal. No alterations were founded at the cardiac magnetic resonance. Due to a previous resting ECG suspected of ventricular preexcitation, an electrophysiological study was performed and showed neither accessory pathways nor inducibility arrhythmias. The asymptomatic and hemodynamically stable patient was discharged and an ambulatorial follow-up was planned.
Conclusion:
This case emphasizes the ever-present difficulty of attributing unequivocal etiological meanings to electrocardiographic alterations.