Study Results
- 217 outpatients (175 men) received verapamil, starting at 240 mg daily and increasing by 80 mg every 2 weeks with an EKG, until the CH was suppressed, side effects intervened, or to a maximum daily dose of 960 mg.
- One patient had 1,200 mg/day.
- 89 patients (41%) had no EKGs.
- 108 patients had EKGs in the hospital; 20 had EKGs done elsewhere.
- 21 of 108 patients (19%) had arrhythmias.
- 13 (12%) had first-degree heart block, at 240 to 960 mg/day, with one requiring a permanent pacemaker.
- Four patients had junctional rhythm, and one had second-degree heart block.
- Four patients had right bundle branch block.
- 39 patients (36%) experienced bradycardia (heart rate less 60 bpm), but verapamil was stopped in only 4 patients.
- In eight patients the pulse rate interval was lengthened, but not to less than 0.2 s.
- The incidence of arrhythmias (disturbed heart rhythms) on verapamil in this patient group is 19% and bradycardia 36%.
Study Conclusion
“We therefore strongly recommend EKG monitoring in all patients with cluster headache on verapamil, to observe for the potential development of atrioventricular block and symptomatic bradycardia.” 1
Summary
Cluster headache can be a devastating and debilitating condition. As with Migraine, there have been no medications developed specifically for prevention, and medications such as verapamil are prescribed off-label.
Dr. Goadsby’s comments summarize the risks and benefits of high dosage verapamil for cluster headache quite well:
“The good news is, when you stop the drug, the effect wears off," said study lead author Dr. Peter Goadsby, professor of neurology at University College London. "So, as long as doctors know about it, and patients with cluster headaches on verapamil know they need EKGs done, it is a completely preventable problem.” 4
“The benefit of taking verapamil to alleviate the devastating pain of cluster headaches has to be balanced against the risk of causing a heart abnormality that could progress into a more serious problem.” 5
