Atrial fibrillation: adverse effects of "pill-in-the-pocket" treatment and propafenone-carvedilol interaction

Drug management of atrial fibrillation in light of guidelines and current evidence: an Italian Survey on behalf of Italian Association of Arrhythmology and Cardiac Pacing

AIM

Atrial fibrillation is a multifaceted disease requiring personalized treatment, in accordance with current ESC guidelines. Despite a wide range of literature, we still have various aspects dividing the opinion of the experts in rate control, rhythm control and thromboembolic prophylaxis. The aim of this survey was to provide a country-wide picture of current practice regarding atrial fibrillation pharmacological management according to a patient's characteristics.

METHODS

Data were collected using an in-person survey that was administered to members of the Italian Association of Arrhythmology and Cardiac Pacing.

RESULTS

We collected data from 106 physicians, working in 72 Italian hospitals from 15 of 21 regions. Our work evidenced a high inhomogeneity in atrial fibrillation management regarding rhythm control, rate control and thromboembolic prophylaxis in both acute and chronic patients. This element was more pronounced in settings in which literature shows a lack of evidence and, consequently, the indications provided by the guidelines are weak or absent.

CONCLUSION

This National survey evidenced a high inhomogeneity in current approaches adopted for atrial fibrillation management by a sample of Italian cardiologist experts in arrhythmia management. Further studies are needed to explore if these divergences are associated with different long-term outcomes.

"Pill in the Pocket" Antiarrhythmic Drugs for Orally Administered Pharmacologic Cardioversion of Atrial Fibrillation

The therapy of atrial fibrillation often involves the use of a rhythm control strategy, in which 1 or more antiarrhythmic drugs (AAD), ablative procedures, and/or hybrid approaches involving both of these options are utilized in an attempt to restore and maintain sinus rhythm. For chronic therapy, an AAD is taken daily. However, for patients with symptomatic but infrequent, acute, but nondestabilizing episodes, the use of an AAD only at the time of an episode that can quickly restore sinus rhythm, generally as an out-patient, without the burden of a daily drug regimen, may be better. This is called "pill-in-the-pocket" therapy. This manuscript reviews the "pill-in-the-pocket" concept, traces its development from its origins using quinidine, to its expansion using class IC AADs, to the more recent investigation of ranolazine for this purpose. Who should get it, what it involves, its efficacy rates and concerns are all discussed.

Effect of CYP2D6 genetic polymorphism on peak propafenone concentration: no significant effect of CYP2D6*10

Aim: The study aims to investigate the clinical implication of nonfunctional poor metabolizer (PM) alleles and intermediate metabolizer (IM) alleles of CYP2D6, including the CYP2D6*10 allele which shows substrate-dependent decrease in enzymatic activity, in antiarrhythmic therapy using propafenone. Materials & methods: We examined serum propafenone concentrations and metabolic ratio, which was expressed as serum concentrations of propafenone to 5-hydroxypropafenone, in 66 Japanese patients with tachyarrhythmias. Results: The peak propafenone concentration and metabolic ratio in CYP2D6 PM allele carriers were higher than those in extensive metabolizer (EM)/EM, EM/IM and IM/IM genotype groups. Conclusion: Results suggest that CYP2D6 PM alleles affect peak propafenone concentration, but the CYP2D6 IM allele CYP2D6*10 has no clinical implication in propafenone dosing.

Cytochrome P450-2D6 Genotype Definition May Improve Therapy for Paroxysmal Atrial Fibrillation A Case of Syncope Following "Pill-in-the-Pocket" Quinidine plus Propafenone

Classes 1A, 1C and III anti-arrhythmics may be ineffective or induce adverse events including potentially fatal arrhythmias when administered in recommended doses. Serum levels of these medications vary widely during conventional dosing due in large part to variations in cytochrome P450-2D6 isoenzyme activity which metabolizes most antiarrhythmics in addition to over 25% of other commonly prescribed medications. 2D6 activity is also profoundly inhibited by some antiarrhythmics and other commonly used medications and varies widely between the individuals of all populations, a pattern which has resulted in separation of subjects into 4 phenotypes and genotypes consisting of poor metabolizers (PM), intermediate metabolizers (IM), efficient metabolizers (EM), and ultra-rapid metabolizers (UM). Patients with a phenotype PM classification almost universally are also genotype PM due to the possession of two inactive 2D6 alleles, with this PM pattern often inducing supratherapeutic and toxic antiarrhythmic blood levels during conventional antiarrhythmic therapy. UM individuals have supranormal levels of 2D6 activity often created by the presence of 3 or more active alleles which often induce subtherapeutic and ineffective drug levels during antiarrhythmic administration in conventional doses. We searched for evidence relating Cytochrome P450-2D6 phenotypes or genotypes to antiarrhythmic metabolism in order to judge whether this analysis might contribute to improved safety and effectiveness of antiarrhythmic medications commonly utilized in the treatment of atrial fibrillation. The available evidence strongly supported these possibilities. We also describe a patient in whom knowledge of his IM/PM CYP2D6 genotype might have prevented the only episode of syncope and myocardial stunning which developed during his 28 years of "Pill-in-a-Pocket" therapy.