Effect of Oral Colchicine on Atrial Fibrillation Recurrence After Electrical Cardioversion: A Randomized, Placebo‑Controlled COLECTRO‑AF Trial

The primary objective is to evaluate documented atrial fibrillation recurrences within six months following electrocardioversion in patients diagnosed with atrial fibrillation, thereby providing data on the durability of rhythm control and informing post‑procedural therapeutic strategies.

A total of 27 participants were enrolled, comprising both female and male adults who were scheduled for electrical cardioversion (ECV). Eligible individuals were required to be older than 18 years, have electrocardiogram‑documented atrial fibrillation prior to the procedure, and achieve successful conversion to sinus rhythm that persisted for at least one hour after ECV. All participants provided written informed consent and were otherwise in general health sufficient to undergo the intervention. The cohort was selected based on these inclusion criteria; no additional lifestyle restrictions such as specific diet or physical activity regimens were stipulated in the protocol.

The COLECTRO‑AF Trial is a Phase III, randomized, double‑blind, placebo‑controlled study evaluating the effect of colchicine 0.5 mg three times daily versus matching placebo on the recurrence of atrial fibrillation after successful electrocardioversion. Eligible adults scheduled for electrocardioversion, with documented atrial fibrillation and sustained sinus rhythm for at least one hour post‑procedure, are enrolled after a screening visit that confirms inclusion criteria and obtains written informed consent. Participants are randomized 1:1 to receive either colchicine tablets or identical placebo tablets for six months. Follow‑up visits are scheduled at 1 month, 3 months, and 6 months post‑electrocardioversion to assess rhythm status, record any repeat electrocardioversion, monitor anti‑arrhythmic drug use, and capture unplanned hospitalizations; the 6‑month visit also serves as the end‑of‑study assessment. The total participant involvement spans approximately six months, with the overall trial recruitment period projected from October 2024 to March 2027. Early termination may occur if a participant withdraws consent, experiences a serious adverse event related to the investigational product, exhibits significant protocol non‑compliance, or is lost to follow‑up.

The investigational product is Colctab 0.5 mg tablets, containing colchicine as the sole active substance (ATC code M04AC01). The tablets are manufactured in a solid oral dosage form (tablet) and are administered orally at a total dose of 3 mg per administration. The specific dosing frequency and duration are defined in the trial protocol and are applied uniformly to all participants receiving the investigational product.

The comparator is a matching placebo tablet, described as cream‑white, circular tablets with a 6 mm diameter and 3 mm thickness, engraved with “0,5” on one side. Apart from the absence of colchicine, the placebo tablets are compositionally identical to the active tablets, ensuring blinding of participants and investigators.

Both study medications are dispensed in accordance with the randomization schedule. Administration occurs under the supervision of study personnel, and adherence is monitored through regular pill counts and verification of returned medication containers. Any deviations from the prescribed dosing regimen are recorded in the case report forms to support compliance assessment.

Efficacy will be assessed by the incidence of documented AF recurrences following electrocardioversion. The primary efficacy parameter is the occurrence of AF within 6 months after the procedure. Secondary parameters include AF recurrences within 1 month and 3 months, time to first redo ECV, use of anti‑arrhythmic drugs (Vaughan Williams class 1 or 3) at 6 months, and survival free of unplanned hospitalization during the same period.

Assessments will be performed at scheduled follow‑up visits occurring at 1 month, 3 months, and 6 months post‑electrocardioversion. Documentation of AF recurrences will be based on clinical records confirming arrhythmic episodes. The interval to a repeat electrocardioversion will be measured from the index procedure to any subsequent ECV. Medication use will be recorded at the 6‑month visit, and hospitalization status will be verified through review of medical records. Comparative analysis of these endpoints between the colchicine and placebo groups will be conducted using appropriate statistical methods for incidence and time‑to‑event data.