2023 AF Symposium

Dr John Day, Salt Lake City, UT
Challenging Case―Ablates Low Voltage High Frequency Areas
Dr. John Day of the Heart Center of St. Mark’s Hospital in Salt Lake City, UT presented the case of a 56-year-old young man in otherwise good health. His BMI was normal. He had had an ablation but was still in A-Fib, according to his Apple watch. “Doc, I’m still having A-Fib. You’ve got to fix it.” He had mild or moderate left atrium enlargement but no clear A-Fib triggers. He didn’t want to be on drugs. He had tried Flecainide which lowered his heart rate too much. He couldn’t exercise on Flecainide.
Dr. Day gave the audience the following choices and asked their opinion.
1. End the case [with no further treatment]
2. Change the antiarrhythmic.
3. Ablate again.


The consensus of the audience was to ablate again. And this was indeed how Dr. Day proceeded.
Second Ablation of Hot Spots
In this patient’s second ablation, all the PVs (pulmonary veins) remained isolated. A-Fib was induced with pacing and Isoproterenol. Dr. Day used electrogram guided ablation.
When in both sinus rhythm and atrial fibrillation, the patient had low-voltage zones (suggestive of left atrial fibrosis) on the posterior wall of the left atrium.
Dr. Day targeted very high frequency signals (hot spots) appearing in low voltage areas. He remarked:
• “We only mark low voltage zones (diseased tissue) if it is low voltage in both sinus rhythm and atrial fibrillation.”
• “We only treat confirmed low voltage zones with high frequency signals…basically with this approach we are only treating diseased tissue with intense abnormal electrical activity which often corresponds to atrial fibrillation driver sites.”
Dr. Day admitted this doesn’t always work. But he has done over 5,000 ablations where this technique is effective.
The patient’s A-Fib didn’t terminate during the ablation, but it did later. Sometimes these patients have to be cardioverted to get them back into normal sinus rhythm.
This patient has been A-Fib free for 18 months and is off of Flecainide.



Editor’s Comments
Dr. Day and his colleagues may have developed a new method of making patients with difficult cases A-Fib free.
Innovation approach. Instead of looking for “potentials”, he ablates areas of low voltage and high frequency. This is an innovative approach and could help many patients with difficult cases.
If you find any errors on this page, email us. Y Last updated: Thursday, May 11, 2023
Return to 2023 AF Symposium Reports