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Importance: There is little evidence to support selection of heart rate control therapy in patients with permanent atrial fibrillation, in particular those with coexisting heart failure.
Objective: To compare low-dose digoxin with bisoprolol (a ß-blocker).
Design, Setting, and Participants: Randomized, open-label, blinded end-point clinical trial including 160 patients aged 60 years or older with permanent atrial fibrillation (defined as no plan to restore sinus rhythm) and dyspnea classified as New York Heart Association class II or higher. Patients were recruited from 3 hospitals and primary care practices in England from 2016 through 2018; last follow-up occurred in October 2019.
Interventions: Digoxin (n = 80; dose range, 62.5-250 µg/d; mean dose, 161 µg/d) or bisoprolol (n = 80; dose range, 1.25-15 mg/d; mean dose, 3.2 mg/d).
Main Outcomes and Measures: The primary end point was patient-reported quality of life using the 36-Item Short Form Health Survey physical component summary score (SF-36 PCS) at 6 months (higher scores are better; range, 0-100), with a minimal clinically important difference of 0.5 SD. There were 17 secondary end points (including resting heart rate, modified European Heart Rhythm Association [EHRA] symptom classification, and N-terminal pro-brain natriuretic peptide [NT-proBNP] level) at 6 months, 20 end points at 12 months, and adverse event (AE) reporting.
Results: Among 160 patients (mean age, 76 [SD, 8] years; 74 [46%] women; mean baseline heart rate, 100/min [SD, 18/min]), 145 (91%) completed the trial and 150 (94%) were included in the analysis for the primary outcome. There was no significant difference in the primary outcome of normalized SF-36 PCS at 6 months (mean, 31.9 [SD, 11.7] for digoxin vs 29.7 [11.4] for bisoprolol; adjusted mean difference, 1.4 [95% CI, -1.1 to 3.8]; P = .28). Of the 17 secondary outcomes at 6 months, there were no significant between-group differences for 16 outcomes, including resting heart rate (a mean of 76.9/min [SD, 12.1/min] with digoxin vs a mean of 74.8/min [SD, 11.6/min] with bisoprolol; difference, 1.5/min [95% CI, -2.0 to 5.1/min]; P = .40). The modified EHRA class was significantly different between groups at 6 months; 53% of patients in the digoxin group reported a 2-class improvement vs 9% of patients in the bisoprolol group (adjusted odds ratio, 10.3 [95% CI, 4.0 to 26.6]; P < .001). At 12 months, 8 of 20 outcomes were significantly different (all favoring digoxin), with a median NT-proBNP level of 960 pg/mL (interquartile range, 626 to 1531 pg/mL) in the digoxin group vs 1250 pg/mL (interquartile range, 847 to 1890 pg/mL) in the bisoprolol group (ratio of geometric means, 0.77 [95% CI, 0.64 to 0.92]; P = .005). Adverse events were less common with digoxin; 20 patients (25%) in the digoxin group had at least 1 AE vs 51 patients (64%) in the bisoprolol group (P < .001). There were 29 treatment-related AEs and 16 serious AEs in the digoxin group vs 142 and 37, respectively, in the bisoprolol group.
Conclusions and Relevance: Among patients with permanent atrial fibrillation and symptoms of heart failure treated with low-dose digoxin or bisoprolol, there was no statistically significant difference in quality of life at 6 months. These findings support potentially basing decisions about treatment on other end points.
Trial Registration: ClinicalTrials.gov Identifier: NCT02391337 and clinicaltrialsregister.eu Identifier: 2015-005043-13.
|Family Medicine (FM)/General Practice (GP)|
|General Internal Medicine-Primary Care(US)|
Small study not meeting its primary objective, but several secondary signals all favoring digoxin. This suggests that further RCTs examining a possible benefit are in order.
This RCT exposes a collateral effect of the evidence-based approach in therapeutic decisions. The refinement of therapies based on adequately performed RCTs is unquestionable, but sometimes this has limited using effective therapies not tested in these trials. Since the publication of the DIG-trial and although the doses used in the trial were not high, digoxin use declined markedly and was mostly restricted as a second option for rate control in patients with AFib. A trial like the RATE-AF is long awaited. Perhaps it was not done earlier because there was no private interest in it, and possibly due to the difficulty of financing by public agencies. As an old and evidence-based cardiologist, I have used digoxin almost in a off-label fashion in many patients with HFrEF, with and without AFib (very low doses, as in the RATE-AF), alone or together with beta-blockers.
As an internist, I find this article can help inform my practice. While the primary outcome of quality of life did not differ, many patient important outcomes like walk distance and NYHA class did. These were in favour of Digoxin; a much maligned drug. In developing countries, this drug is relatively inexpensive and probably underused! I would recommend careful use of Digoxin!
A small trial but with very interesting result. This will likely lead to increasing use of digoxin.