Coping with CABANA: Look Beyond the Headlines
J. Brian DeVille, MD, FHRS, East Medical Director for Electrophysiology - BSWH
May 10, 2018 — Today at the Heart Rhythm Society (HRS) Annual Scientific Sessions, the results of the CABANA trial were announced. CABANA, an international research trial that enrolled over 2,200 patients, was designed to compare the strategy of ablation to the strategy of medical therapy for atrial fibrillation. Patients were followed for years – some up to eight years. Unlike most other studies, the primary endpoint was a combination of survival, disabling stroke and cardiac arrest, not freedom from abnormal heart rhythms.
At The Heart Hospital Baylor Plano, we were proud participants in this extremely important study. Dr. Hafiza Khan and I attended the CABANA Investigators' Meeting on the evening of Wednesday, May 9, where those of us who were part of the study were informed of the results. The following morning, the results were presented at the "Late Breaking Trials" session at the HRS meeting. This was the most highly anticipated event of the meeting, and immediately after the presentation, the (medical) Twitter universe exploded.
Many of the tweets started off with a headline along the lines of: Ablation shows no mortality benefit to medical [drug] treatment in survival for atrial fibrillation. Others basically said: Ablation does much better than medication. However, it is very difficult to tell the full story of a study that has been developing for over 10 years in a tweet, especially in the first sentence.
So, what is in the rest of the story beyond the Twitter headlines? While it is true that using a statistical analysis called "Intention to Treat (ITT)" ablation showed no statistically significant advantage to medical therapy, that analysis does not tell the whole story. In that analysis, ablation did show a trend toward better outcomes regarding the primary endpoint, but the ITT analysis meant that over 100 patients who were designated to get ablation but did not undergo the procedure were included in the analysis.
Analyzing those patients who actually received the treatment to which they were randomized (using "Per Protocol" analysis) did show a statistically favorable outcome with ablation. Certain groups (minorities, younger patients, patients with heart failure) also did significantly better with ablation than medication.
In addition, hospitalization rates for cardiovascular problems were significantly lower in the ablation group. There was a measurable reduction in recurrence of atrial fibrillation after ablation, as compared to drug therapy. Further details regarding the burden of atrial fibrillation, economic data and many other findings will be forthcoming.
CABANA was a landmark trial looking at a complex set of questions. As a physician, I am proud that our institution contributed to the study. Overall, the feeling of the investigators was that ablation performed favorably compared to medical therapy, showing significantly less recurrence of the problem being treated and lower hospitalization rates for cardiovascular issues.
We look forward to the publication of the full study and the different analyses that will follow, including detailed looks at subgroups of patients.
[Disclosures: Research for Biosense Webster, Boston Scientific, and Abbott; Instructor for Biosense Webster. All of these companies supplied unrestricted grants to fund this NIH/NHLBI study.]
Physicians are members of the medical staff at one of Baylor Scott & White Health's subsidiary, community or affiliated medical centers and are neither employees nor agents of those medical centers, Baylor Scott & White The Heart Hospital – Plano or Baylor Scott & White Health.