In atrial fibrillation (AF) conventional practice is to stringently control ventricular rate. However, the effect of rate control on exercise performance is not clearly established and stringent control may in fact worsen quality of life (QOL). We examined whether stringent control of the ventricular response to AF in fact had an adverse effect on exercise performance and QOL.
Exercise performance was measured by a 6-minute walk test and QOL by a questionnaire, before and after decreasing control of ventricular response by beta blockers, calcium channel blockers and digoxin in various combinations.
Eight patients with chronic AF were all being treated with multiple drugs to rigorously control their ventricular rate, reflecting the practice in our referred population, not our study design. Their ages were 60-80 years; six were male. Seven had hypertension, two diabetes, and two coronary heart disease. None had symptoms of heart failure on treatment and 6 of 8 have normal left ventricular ejection fractions. Mean left atrial diameter was 4.7cm + 0.54 SD. Upon discontinuation of one or more drugs, average exercise heart rate increased from 84.3 bpm + 12 SD to 106.5 + 13, p < 0.002. Every subject walked further in 6 minutes (1,428 feet + 438 to 1797 + 535, p<0.002), and QOL improved in all but one (47.8 + 13 to 61.4 + 7, p < 0.005). The increased distance walked correlated with the improved QOL (r = 0.81). We intended a crossover design; however, all but one of our patients refused to resume their entry medications. In that patient, stricter control lead to a decrease in distance walked and worsened QOL.
Adequate control of AF was achieved with fewer medications when “adequacy” was defined by exercise performance and QOL.
Guidelines for control of rate in AF require further study with a crossover design but careful control may be inadequate control.
U. Fatima, None.