WAUSAU, WISCONSIN. Flecainide and propafenone are both effective in terminating AF episodes when used on demand at the onset of an episode. Studies have shown that these drugs effectively convert 70-80% of patients with paroxysmal AF within 6 hours or less. Unfortunately, while safe for lone afibbers both of these Class 1C drugs can induce potentially fatal ventricular arrhythmias in patients with underlying heart disease. Thus a pill-in-the-pocket (PIP) approach is not currently available for this group of non-lone afibbers.
Four American electrophysiologists/cardiologists now report that ranolazine (Ranexa), a drug used in the treatment of angina pectoris may be an effective and safe PIP for afibbers with underlying heart disease. The four physicians compared notes in an uncontrolled, non-placebo-controlled retrospective chart review. They found that 25 of 35 patients (71%) who had been in AF for 3 to 48 hours converted to normal sinus rhythm within 6 hours of being administered 2000 mg of ranolazine orally. It is worth noting that 86% of the study participants had underlying structural heart disease. None of the patients experienced any cardiovascular side effects or worsening of afib symptoms.
The authors point out that ranolazine is safe for afibbers with underlying heart disease, has no pro-arrhythmic effects, and does not induce atrial flutter. It works to prevent afib by inhibiting abnormal late sodium channel current, increasing atrial refractoriness, and reducing pulmonary vein firing (PACs). The authors conclude that high-dose ranolazine is as effective as propafenone and flecainide, and that its conversion rate of 71% is substantially better than the 39% within 8 hours rate reported in the literature for placebo.
In an accompanying editorial two physicians from the Mayo Clinic point out that the study had a major flaw – it had no control group of individuals matched for age, gender, duration of afib, and concomitant illnesses. Nevertheless, they suggest that carefully controlled studies are warranted to establish "whether ranolazine is the promised drug or is just too good to be true."
Murdock, DK, et al. The conversion of paroxysmal or initial onset atrial fibrillation with oral ranolazine. Journal of Atrial Fibrillation, Vol. 2, August 2010, pp. 705-10
Gard, JJ and Asirvatham, SJ. Ranolazine for atrial fibrillation: Too good to be true? Journal of Atrial Fibrillation, Vol. 2, August 2010, pp. 711-14
Editor's comment: This new PIP drug looks promising and may be worth trying for afibbers with underlying heart disease. However, until more data is available lone afibbers should probably stick with propafenone or flecainide as these two drugs have undergone proper clinical trials to establish their effectiveness and safety.