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Atrial fibrillation (AF) is the most common arrhythmia in elderly patients (pts). Our recent studies suggest that acquired long QT syndrome is common in elderly pts. The distortion of the end of the T wave by artifacts of f waves, however, is a major factor making QT measurement difficult in the presence of AF. This study aimed to find an effective solution to that problem.
ECG analysis was performed in 108 pts (age 65±11 yrs, 63% M) with AF. The frequency of apparent f waves, the highest f waves (f-max), the least visible f waves (f-min) and T waves showing best morphology (best-T) and with least artifact of f waves among 12 leads was evaluated.
Apparent f waves are commonly present in limb leads and V1, and f-max (0.12±0.04 mV) is most frequently shown in lead II (90%), followed by leads aVF (51%) and III (41%), respectively. The f-min is most frequently seen in V2 (78%). The best-T is mostly found in precordial leads except V1. The highest frequency of best-T is observed in lead V2 (83%), followed by V3 (74%).
In the presence of AF, QT measurement should be taken in the lead showing best T wave morphology and with least artifacts of f waves, such as precordial leads V2-3. Leads II, III, aVF and V1 should be avoided for QT measurement considering the high prevalence of f-wave artifacts and poor morphology of the T wave.