Preexcitation Pitfalls (Part 3): Wide, Irregular, Fast…Avoid AV Nodal Blockers

ECG Weekly Workout with Dr. Amal Mattu

HPI

A 53-year-old man presents with palpitations and lightheadedness. The following ECG is obtained on arrival and appears very rapid and irregular with changing QRS morphologies. He starts showing signs of instability shortly after arrival.

Before watching this week’s workout, review the arrival ECG carefully and consider:

    1. What three ECG features should immediately raise concern for preexcited AF rather than “routine AF with aberrancy” or VT?
    2. Why can AV nodal blockers convert SVT but precipitate ventricular fibrillations in AF with WPW?
    3. In the unstable patient, what is the fastest and safest definitive management strategy?