Wide-QRS rhythms can be difficult to diagnose from the ECG alone. This difficulty is compounded when the rate is fast, as it can be hard to determine if P waves are present before the QRSs, or dissociated, or absent.
This ECG and rhythm strip were donated to the ECG Guru by Ryan Cihowiak. We don't have clinical information on the patient, unfortunately. It is a great example, however, of how difficult WCT can be to diagnose.