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Rate Modulation Drugs in Atrial Fibrillation: What is the Clinical Impact?

Atrial fibrillation (AF) remains the most common arrhythmia encountered in clinical practice, having a negative long-term prognosis on patients while imposing significant costs on healthcare, expenses comparable in magnitude to those of congestive heart failure. Due to rapid progression of ablation technologies and techniques, we now have the opportunity to treat and potentially cure this arrhythmia effectively; however, the invasive approaches are limited to selected groups of patients, while the success rates of the procedure are widely variable. Concurrently, using antiarrhythmic medical therapy is an option fraught with limitations related to efficacy, drug tolerance, and side effects. It is in this particular environment that the electrophysiology and cardiology communities have to make optimal use of rate control medications, whether aiming to bring the heart rate down to acceptable levels, or even improve the prognosis of the patients in AF. The outcomes and prognosis of patients receiving rate control medications have been previously evaluated using various parameters. RACE II investigators1 have successfully shown that a lenient heart rate control is as effective as strict rate control when looking at hard endpoints of death from cardiovascular causes, heart failure hospitalizations, stroke and bleeding and life-threatening arrhythmic events. Simultaneously, AF rate (AFR) has also been found to have prognosis implications: high AFR suggests worse prognosis in regard to sinus rhythm maintenance,2,3 while low AFR could be associated with worse outcomes in patients with congestive heart failure4 possibly being a sign of remodeling or a poor prognosis biomarker. More complex parameters have also been studied in an effort to reach the “Holy Grail” of best prognosis when employing a rate control strategy. Early indications of the prognostic value of ventricular response irregularity measures came from 2 small series published in the middle of the 1990s that reported significant associations between a reduced RR variability during AF and clinical deterioration