Botulinum Toxin Injection Plus Topical Diltiazem for Chronic Anal Fissure: A Randomized Double-Blind Clinical Trial and Long-term Outcome

BACKGROUND: Chemical sphincterotomy avoids the risk of permanent incontinence in the treatment of chronic anal fissure, but it does not reach the efficacy of surgery and recurrence is high. Drug combination has been proposed to overcome these drawbacks. OBJECTIVE: This study aimed to compare the clinical, morphological, and functional effects of combined therapy with botulinum toxin injection and topical diltiazem in chronic anal fissure and to assess the long-term outcome after healing. DESIGN: This is a randomized, controlled, double-blind, 2-arm, parallel-group trial with a long-term follow-up. SETTINGS: This study was conducted at a tertiary care center. PATIENTS: A total of 70 consecutive patients were referred to the gastroenterology department of a hospital in Valencia, Spain. INTERVENTION: After botulinum toxin injection (20 IU), patients were randomly assigned to local diltiazem (diltiazem group) or placebo gel (placebo group) for 12 weeks. MAIN OUTCOME MEASURES: The primary outcome was fissure healing (evaluated by video register by 3 independent physicians). Secondary outcomes included symptomatic relief (30-day diary), effect on anal sphincters (manometry), safety, and long-term recurrence (24 months and 10 years). RESULTS: Healing was achieved per protocol in 13 of 25 (52%) patients of the diltiazem group and 11 of 30 (36.7%) patients of the placebo group (p = 0.25); on an intention-to-treat basis in 37.1% and 31.4% (p = 0.61). Both groups displayed significant reduction of anal pressures. Thirty percent reported minor and transitory incontinence, without differences between groups. Nine (69.2%) of the diltiazem group and 6 (54.5%) of the placebo group experienced a relapse at 24 months (p = 0.67). The overall recurrence rate at 10 years was 83.3% (20/24 patients). LIMITATIONS: This study was limited by the loss of patients during the trial. The low healing rate led to a small cohort to assess recurrence. CONCLUSIONS: Combined botulinum toxin injection and topical diltiazem is not superior to botulinum toxin injection in the treatment of chronic anal fissure. Both options offer suboptimal healing rates. Long-term recurrence is high (>80% at 10 years) and might appear at any time after healing.