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For patients undergoing catheter ablation for atrial fibrillation (Afib), there was no signal that a brief course of colchicine reduced atrial arrhythmia recurrence or improved clinical outcomes when taken for 10 days starting right before the procedure, a small pilot trial found.

By 14-day Holter monitoring, colchicine did not prevent atrial arrhythmia recurrence immediately after ablation (31% vs 32% with placebo; HR 0.98, 95% CI 0.59-1.61), nor at 3 months (14% vs 15%; HR 0.95, 95% CI 0.45-2.02), reported Alexander Benz, MD, MSc, of the Population Health Research Institute at McMaster University in Hamilton, Ontario, and colleagues.

The anti-inflammatory drug also did not reduce the composite of emergency department visits, cardiovascular hospitalizations, cardioversions, or repeat ablations during a median follow-up of 1.3 years (29 vs 25 per 100 patient-years; HR 1.18, 95% CI 0.69-1.99).

Yet IMPROVE-PVI was "not sufficiently powered to definitively exclude a clinically significant benefit with colchicine," Benz and team cautioned in their report published in .

They highlighted the finding that the incidence of post-ablation chest pain suggestive of pericarditis was reduced with colchicine (4% vs 15%; HR 0.26, 95% CI 0.09-0.77).

"This reduction was observed within days following catheter ablation, suggesting anti-inflammatory effects of short-term treatment with colchicine. This finding is in line with evidence on the efficacy of colchicine in the prevention and treatment of pericarditis and postpericardiotomy syndrome following cardiac surgery," Benz and colleagues wrote.

"Although our definition of pericarditis differed from more stringent definitions, the observed beneficial effect of colchicine on post-ablation chest pain in this placebo-controlled, double-blind trial was clinically meaningful," they argued.

Colchicine is a widely prescribed anti-inflammatory agent that is known to have cardiovascular prevention benefits.

Given that the success of catheter ablation via pulmonary vein isolation is often marred by recurrent atrial arrhythmias, and such arrhythmias are predicted by inflammatory biomarkers, the trialists had hypothesized that colchicine would be of help.

As expected, colchicine therapy resulted in diarrhea as a side effect in IMPROVE-PVI. Yet the incidence of diarrhea was particularly high in this trial (26% vs 7% with placebo; HR 4.74, 95% CI 1.95-11.53) compared with prior observations.

"Possible reasons for the discrepancy in diarrhea incidence between our and other studies include differences in outcome definitions and patient characteristics, as well as potential interaction of colchicine with concomitant medications," the authors suggested.

The present trial had been conducted at a single center and enrolled patients scheduled for catheter ablation. Those with contraindications to colchicine, namely those taking certain medications or those with serious gastrointestinal disease, overt hepatic disease, or severe renal disease were excluded.

Participants were randomized to colchicine 0.6 mg twice daily or placebo for 10 days, starting within 4 hours before ablation.

Recurring atrial arrhythmia was defined as Afib, atrial flutter, or atrial tachycardia >30 seconds on two 14-day Holters performed immediately and at 3 months following ablation.

The study cohort consisted of 199 patients (median age 61 years, 22% women, 70% undergoing their first ablation procedure) who had either received radiofrequency ablation using the Carto 3 system from Biosense Webster (79%) or cryoballoon ablation with Medtronic's Arctic Front system (21%).

Antiarrhythmic drugs were prescribed at discharge for 75% of patients. At 6-month follow-up, the proportion of patients off antiarrhythmic therapy was 62.2% and 57.0% of the colchicine and placebo groups, respectively.

One person died of sepsis in the colchicine group, whereas there were no deaths in the placebo group.

Benz and colleagues acknowledged that on top of the small sample, they did not look for recurrent arrhythmias using implantable loop recorders, likely resulting in an undercounting in both treatment groups.

Since IMPROVE-PVI was conducted, another technology for catheter ablation, pulse field ablation (PFA), was FDA approved. Medtronic's PulseSelect PFA system was approved last week, while rival PFA system Farapulse from Boston Scientific has yet to be given the green light.

Unlike conventional catheter ablation for Afib, PFA avoids thermal damage to the esophagus or phrenic nerve.

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