AF ablation Atrial fibrillation

Take-home messages from Western AF 2018

The Western AF symposium may have had corporate sponsors, but it was no boondoggle. The sessions start at 0715 and go through 1830. Your head spins at the end of the conference. I learned a lot.

Here are some fast-writing thoughts:

New Energy Source for Ablation

Electroporation looks to be a promising new energy source for ablation. The problem with RF-energy, or cryo-energy, is collateral damage. The atria lie close to the esophagus, coronaries and phrenic nerves.

Electroporation “ablates” heart tissue without damaging structures nearby. It’s also called pulsed field ablation. This is damn early data. We have to wait for more studies.

Sham Trial for AF ablation is coming:

I wrote about this on | Medscape Cardiology in 2016.

As long as the target for AF ablation is reduction of symptoms, then it has to pass a sham control.

Professor Carina Blomstrom-Lundqvist presented results of the CAPTAF trial, which was a study of AF ablation in relatively young people. She found that the difference in quality of life score after ablation was not driven by the difference in AF burden at 12 months. Translation: some people feel better after AF ablation but still have AF. That is provocative.

Two leaders in the field made comments on this:

In addition to comments from two of the giants in EP, I also spoke with another (unnamed) leader in EP who said his group has talked among themselves about doing a sham trial but did not want to broadcast it for fear that someone else beats them to it.

We need the sham trial to sort out the placebo effect of ablation. Look up the ORBITA trial.

Left Atrial Appendage Closure Meets little Resistance:

There were multiple talks on left atrial appendage closure. All of them positive. Again, Professor Gerhard Hindricks took to the Q & A microphone and expressed concern of the evidence in support of this procedure.

During one session in which a panel of EP doctors expressed great enthusiasm about the procedure, Dr. Elaine Hylek, an internal medicine doctor and trialist for anticoagulant drugs, stood up to the mic and said, “you guys are scaring me.”

Her concerns are similar to mine:

  • The evidence suggesting LAAO is noninferior to warfarin are not convincing
  • The device has not been tested in patients ineligible for anticoagulants (these higher risk patients may be less likely to benefit.)
  • The device has not been tested against the direct-acting oral anticoagulants, dabigatran, rivaroxaban and apixaban.

AF and Heart Failure:

Western AF celebrated recent publication of CASTLE-AF.

CASTLE-AF compared ablation of AF vs continued medical management in patients with heart failure. AF ablation reduced death rates and hospital admission for heart failure.

My comments on this trial induced great criticism from Dr. Milton Packer, a heart failure expert. Dr. Packer’s concerns centered on the methods of the trial.

Professor Jon Kalman (Melbourne, Australia) gave a talk that may have changed my mind about AF and heart failure. He discussed a recent study from his group called CAMERA-MRI. They studied patients with AF and heart failure, comparing a rate control strategy vs ablation. Patients in the ablation group had much greater improvements in heart function (as measured by the ejection fraction).

What this data might change is the idea that AF causes heart failure (heart muscle weakness) only if the rate is excessive. In CAMERA-MRI, all patients had good rate control. Those with heart rate control improved their EF by 4.4%. But those in the ablation group improved by 18%.

It’s possible therefore that the AF itself, the irregularity, or something else, contributes to weakness of the heart. CAMERA-MRI isn’t the only study that found this. The Bordeaux group published similar findings in 2004.

Heart rate control remains a crucial part of treatment for AF.  If you don’t get good heart rate control, heart failure is likely.

But the combination of previous studies on AF ablation and heart failure, and CAMERA-MRI and CASTLE-AF all point towards a benefit for ablation in suitable patients.

The latter point is key: CASTLE-AF enrolled young, mostly male patients with only moderate degrees of heart muscle weakness. This data does not apply to the vast majority of patients with heart failure who are older and have multiple other problems. EPs mustn’t run amok offering ablation to patients unlike those in the CASTLE-AF.

And we still need to answer Dr. Packer’s criticisms of CASTLE-AF.

Finally, Dr. Doug Packer from Mayo gave a prelude to the CABANA trial. This comparison of drugs vs ablation in older patients with AF will look at hard outcomes, like death and stroke. It will be a landmark trial for our field.