WPW ‘A’ in AF: Positive Concordant Precordial Pattern

Report:

Atrial fibrillation with (very) rapid ventricular response.

Anomalous conduction (WPW type ‘A’)

Wolff-Parkinson-White Syndrome

Comment:

The rate approaches 300/min but is obviously irregular. The trace is pathognomonic of WPW. The positive concordant precordial pattern seems to give way to Rs or even rS complexes in V5 and V6. The reason for this is not quite clear – the sinus rhythm ECG (below) is certainly typical of WPW ‘A’ conduction. This may be due to the sensitivity of all ECGs with left or right axis deviation in the frontal plane to vertical lead displacement in the precordial leads. Another possibility is multiple bypass tracts. Another would be an increase in normal conduction contribution toward the end of the recording – a change in fusion proportions, so to speak. This is not likely. In AF, the QRS tends to be either completely anomalous (most of the time) or normal (few beats here and there). Anyway, the V4 and V5 after surgery (not shown) were normal qR complexes – their fusion would have contributed no S waves here.

The youth tolerated the tachycardia surprisingly well (for the rate, not as a differential diagnostic point for or against VT) and was cardioverted with IV flecainide. Who now remembers procainamide, once the drug of choice here?

He was referred to Sydney for electrophysiologic studies to determine the exact location and nature of the anomalous tract(s) prior to surgery. Type ‘A’ pre-excitation implies insertion of the bundle of Kent into the left ventricular myocardium, but actual EPS mapping is necessary for surgical ablation.