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Catheter ablation an ‘acceptable treatment strategy’ for atrial fibrillation
BOSTON — In patients with atrial fibrillation, catheter ablation conferred better outcomes compared with drug therapy in on-treatment and per-protocol analyses, but not in an intention-to-treat analysis, according to the results of the Catheter Ablation vs. Antiarrhythmic Drug Therapy in Atrial Fibrillation, or CABANA, trial.
The analyses differed because nearly 30% of patients assigned to drug therapy eventually received ablation, and nearly 10% of patients assigned to ablation did not undergo the procedure, Douglas L. Packer, MD, professor of medicine and consultant in the division of heart rhythm services, department of cardiovascular medicine, Mayo Clinic, said during a presentation at the Heart Rhythm Society Annual Scientific Sessions.
New data reported
At a median follow-up of 4 years, the difference in the primary endpoint, including death, disabling stroke, serious bleeding or cardiac arrest, between patients assigned ablation and those assigned drug therapy was not significant in the intention-to-treat analysis (HR = 0.86; 95% CI, 0.65-1.15). However, the on-treatment analysis (HR = 0.67; 95% CI, 0.5-0.89) and the per-protocol analysis (HR = 0.73; 95% CI, 0.54-0.99) favored ablation.
“You can’t benefit from a therapy if you don’t get the therapy,” Packer said at a press conference.
In the intention-to-treat analysis, the catheter ablation group had less atrial fibrillation recurrence (HR = 0.53; 95% CI, 0.46-0.61) and a lower risk for all-cause mortality or CV hospitalization (HR = 0.83; 95% CI, 0.74-0.93), but similar risk for all-cause mortality (HR = 0.85; 95% CI, 0.6-1.21), disabling stroke (HR = 0.42; 95% CI, 0.11-1.62), serious bleeding (HR = 0.98; 95% CI, 0.62-1.56) and cardiac arrest (HR = 0.62; 95% CI, 0.24-1.61) compared with the drug therapy group, Packer said.
He also noted that the intention-to-treat primary outcome favored catheter ablation in patients aged younger than 65 years (HR = 0.52; 95% CI, 0.27-1), but not in patients aged 65 to 74 years (HR = 0.84; 95% CI, 0.57-1.23) or those aged 75 years or older (HR = 1.46; 95% CI, 0.8-2.67).
In the on-treatment analysis, all-cause mortality or CV hospitalization favored the ablation group. In the per-protocol analysis, the treatment effect of catheter ablation for the primary outcome was even greater in those aged younger than 65 years, he said.
Adverse event rates were low in both groups.
“Since I got the data, I found that it’s changed my approach with patients,” Packer said at the press conference. “It is much less common for me to say, ‘let’s just go with the drug and see how it goes.’ I would take that approach if I were unsure that the patient’s symptoms were because of the atrial fibrillation.”
The study population comprised 2,204 patients from 126 sites worldwide with any type of atrial fibrillation eligible for ablation and at least two rate control or rhythm control drugs. Patients younger than 65 years could be included if they had at least one risk factor for CVD or cerebrovascular accident.
In the ablation group (median age, 68 years; 37% women), 90.8% of patients had ablation and 19.4% received repeat ablation. In the drug therapy group (median age, 67 years; 37% women), 99.6% were treated with drugs and 87.2% took at least one rhythm control drug, while 27.5% were crossed over to ablation, Packer said.
Further analyses to come
“Ablation is an acceptable treatment strategy for treating AF with low adverse event rates even in higher-risk patients,” Packer concluded.
When the results are published, more information will be available about who benefited most from ablation, he said. Quality-of-life and health care economics analyses will be presented at the European Society of Cardiology Congress in August, he said.
“At the end of the day, we think this is a very meaningful trial,” Packer said at the press conference. – by Erik Swain and Alaina Tedesco
Reference:
Packer DL, et al. LBCT01-05. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 9-12, 2018; Boston.
Disclosure: The study was funded by Biosense Webster, Boston Scientific, Medtronic, the NIH and St. Jude Medical. Packer reports he has financial ties with numerous device companies.
Perspective
Back to TopThis may change my decision-making process as to who gets ablation. We can now tell patients that those who underwent the procedure did better. I will also tell them that if you include everybody, the results did not show as much of a difference. But physicians and patients will likely make the assumption that if you get the treatment, you might do better. Of course, I will not start strong-arming people to get ablation, because I did not see the stroke and mortality benefit in the entire population.
Perspective
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We have never had a trial of this type with average 4-year follow-up. Complications and efficacy were captured well.
We learned that there is not a mortality disadvantage to doing ablation, so it is good to know we are not hurting a group of patients. It takes trials this big and long to capture rare events. And sometimes when a trial comes up neutral like this, it provides equipoise. There is more than one valid option. There are some signals as to who may benefit most from ablation, which we will learn more about when the data are published.
Of note, there was a more than 30% reduction in the primary endpoint (mortality, disabling stroke, serious bleeding, cardiac arrest) in favor of ablation in the analysis of patients who actually received an ablation (on treatment analysis). That was important.
As expected, people who had ablation were more likely to be in sinus rhythm and this confirmed over a very long follow-up that our procedures have efficacy.
For this trial, symptoms were not a prerequisite for getting into the study, so perhaps for older and truly asymptomatic patients, we don’t have to be as aggressive with ablation. There were some signals in subgroup analysis that patients over 75 may not benefit as much. Patients under 65 and those with congestive HF seemed to derive the most from ablation.
Clinically, this was an extremely important trial. It will change clinical practice. I feel in my practice that my AF patients who are younger, with HF and especially those with symptoms should be offered ablation and perhaps earlier. Older patients and especially those without a lot of symptoms may be managed more conservatively without denying them a mortality benefit.
Perspective
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You can’t benefit from ablation if you don’t get ablation, and there was a difference in the population who actually received ablation for the combined endpoint of death, stroke, cardiac arrest and serious bleeding. It’s hard to know how to interpret what has been publicized so far knowing that many patients who were supposed to receive ablation did not. We also need more information about the drug group. Were they mostly on amiodarone?
We also need to learn more about the benefit of ablation in younger patients. Was it because they are younger, or is it because older patients have longer-standing disease and may have more left atrial enlargement and more scarring that might make them worse candidates for ablation?
We need more data before we decide to change practice. I hope that people will not decide to no longer do ablation because the intention-to-treat analysis showed no difference. When further analyses are performed, we may find certain groups of patients may not benefit as much. Some of it is likely to confirm things we already knew, such as if you’re older and have had AF for a long time, you have a lot of fibrosis and a large atrium and may be less likely to benefit from ablation. But we need to see more detail.