Introduction

Atrial fibrillation (AF) is the most common sustained abnormal cardiac rhythm in adults.¹ Overall AF prevalence in New Zealand is estimated to be around 2–3%, which rises to at least 5% in those aged ≥65 years.^{2, 3} Stroke, heart failure and dementia, with reduced quality of life, are strongly associated with AF, as well as increased all-cause mortality.^{1, 4}

AF accounts for 0.5% of all ED presentations, with up to 40% of these patients being admitted to hospital each year.⁵ There is wide variation in the ED management of acute AF internationally.⁶ Recent studies suggest that a high proportion (63–72%) of patients with acute uncomplicated AF/atrial flutter (AFL) spontaneously revert to sinus rhythm (SR), negating the need for ED cardioversion.^7-9 Research also suggests that delayed cardioversion for AF is non-inferior to early cardioversion in achieving a return to SR after ED presentation.⁹ Furthermore, recent studies highlight that ED plays an important role in the initiation of anticoagulants in patients with increased stroke risk, compared to deferring to the patient's usual longitudinal care provider.^10-15

In September 2015, Christchurch Hospital ED, New Zealand, adopted a multidisciplinary clinical AF and AFL (AF/AFL) pathway (thereafter termed AF pathway), with collaboration from medical specialists and nurses in emergency medicine and cardiology.⁸ This pathway involves a conservative ‘rate-and-wait’ approach for haemodynamically stable patients with acute uncomplicated AF/AFL, anticoagulant prescribing advice, and next working day AF-clinic follow-up incorporating delayed cardioversion when required. The pathway recommends metoprolol succinate or diltiazem as rate-control agents, with the majority of clinicians choosing to prescribe metoprolol succinate. Patients who convert to SR or achieve a heart rate of ≤110 beats per minute with relief of AF-related symptoms and remain haemodynamically stable are discharged home with a review scheduled for the next working day at the acute AF clinic. Here they are seen by a cardiology nurse, where an ECG is taken, and assessed by a cardiology registrar, with a consultant cardiologist available for further advise. A preliminary analysis of this pathway showed that over two-thirds (73%) of AF pathway patients spontaneously reverted to SR at ED discharge or by follow-up in clinic (97% attended within the next working/business day). The conservative strategy for acute uncomplicated AF/AFL within a treatment pathway safely prevented hospitalisations, unnecessary electrical cardioversions and ensured the delivery of longitudinal AF/AFL care.⁸ We aimed to evaluate the impact of this pathway on patient clinical outcomes and safety in an extended cohort.

Methods

Results

A total of 2673 presentations were identified of which 416 were not in AF/AFL on arrival in ED, 1455 AF/AFL was not the primary presenting issue, 206 were not seen by an ED doctor, 87 had missing ED assessment record and 149 were already included in the study. This left 360 presentations: 182 pre-pathway and 178 post-pathway (Table 1). Baseline characteristics of patients at ED presentation are displayed in Table 1.

The median ED LOS was similar for both groups (3.9 h vs 3.8 h, difference −0.1 h, 95% CI −0.6 to 0.3). Cardioversions in ED decreased by 81.3% (n = 32 vs n = 6), a −14.2% net difference (95% CI −20.9 to −7.5). There was a 13.1% net (30.1% relative) reduction in hospital admissions from ED in the post-pathway group (n = 54) compared to the pre-pathway group (n = 79, 95% CI −23.5 to −2.6%), although eight patients in the post-pathway group (4.5%) were subsequently admitted from AF clinic. The cumulative time spent in hospital was 813 h lower for the post-pathway group in the present study (95% CI −1731 to 107 h).

At discharge 23% of patients who were managed using the pathway had reversed spontaneously to SR. This increased to 64.5% (40/62) by the time patients had presented to the AF clinic. Eight (12.9%) AF clinic patients required admission (seven for cardioversion and one with acute coronary syndrome). The total number of cardioversions in the post-pathway group, accounting for those that occurred in ED, for patients admitted directly from ED, and those admitted from AF clinic (n = 32) was reduced by 50.7%, compared to the pre-pathway group (n = 65), with a net difference in cardioversion rates of 17.7% (95% CI −27.3 to −8.2%).

The rates of representation to ED with AF within 7 days (−0.5% difference, 95% CI −5.1 to 4.1%) and within 1-year (−6.0% difference, 95% CI −16.0 to 3.9%) were similar between both cohorts (Table 2). The rate of re-presenting to ED with an ischaemic stroke within 1-year was the same in both groups (1.1%: two patients). The 7-day all-cause mortality, with one patient in each group, was similar (0.1% difference, 95% CI −1.5 to 1.6%). Patients were followed for a median of 1839 days (range 7–2262) during which 30 in the pre-pathway and 23 in the post-pathway group died. The HR for death for the post-pathway group relative to pre-pathway group was 1.05 (95% CI 0.58–1.88).

The proportion of patients indicated for anticoagulation as per 2020 ESC Guidelines were similar between the two groups (59.9 and 60.1%).¹⁷ The number of patients who are deemed ‘high risk’ for anticoagulation as per their HAS-BLED score were also similar between the two groups (6.0 vs 9.0%).²⁰ Guideline-appropriate prescription of anticoagulants in ED (CHA₂DS₂VASc score Male ≥2, Female ≥3) showed an increase by 3.5% (12 vs 18%).

Discussion

In this pre-post-implementation study of the integrated acute AF pathway, we showed that using a ‘rate-and-wait’ strategy safely decreased hospital admissions, with most patients spontaneously reverting to SR within 24–48 h, meaning fewer patients required cardioversion.

After the implementation of this pathway, the overall utilisation of cardioversion reduced by 50.7% (net 17.7% reduction). Not only does this reduce patient exposure to cardioversion risk, but also sedation risk and other iatrogenic risks of longer hospital stays. Although retrospective, and therefore unable to imply causation, this confirms and supports the accumulating body of evidence in favour of delayed cardioversion as a safe and effective strategy of managing haemodynamically stable patients presenting to the ED with recent-onset symptomatic AF/AFL.^{7, 9}

Similar to previous studies evaluating different AF treatment pathways in the ED, the utilisation of the AF pathway described in the present study reduced the rate of hospital admission by 30.1% (a net 13.1%).^{6, 21} Despite the significant reduction in hospitalisation, AF-related representation and all-cause mortality rates were similar between the two groups, positioning the AF pathway as a safe alternative to early cardioversion and/or inpatient management of acute uncomplicated symptomatic AF/AFL. Furthermore, implementation of this AF treatment strategy likely leads to significant savings by reducing the costs associated with unnecessary cardioversions, avoidable hospitalisations and their potential complications.⁵

Guideline-appropriate anticoagulation for patients with AF increased by a net 3.5% after implementation of this pathway from a low base. The poor rates of anticoagulation, both in the community and the ED, are a long-standing problem.¹⁷ However, a study examining a later cohort of patients managed under the AF pathway (May 2016 to April 2017, n = 143) demonstrated that 89% of those with a CHA₂DS₂-VASc score ≥2 had been prescribed anticoagulation by the time they were discharged from the AF clinic.⁸

Findings from the present study and previous analyses have resulted in changes to the design of this pathway.⁸ The pathway now contains more specific recommendations for anticoagulation on discharge, as well as recommending follow-up for all patients, no matter what their rhythm at discharge. Next-day follow-up on this pathway now occurs in a community clinic, with referral back to the cardiology service if required, aimed to improve access to follow-up and reduce ED re-presentations. There is work focused on determining whether particular factors may predict a failure to spontaneously revert to SR within a short timeframe in haemodynamically stable patients presenting to ED with uncomplicated acute AF, and therefore warranting active management with early cardioversion.^{22, 23}

Conclusions

To conclude, a conservative ‘rate-and-wait’ strategy with early outpatient follow-up for patients presenting to ED with acute symptomatic AF/AFL may reduce cardioversions and hospital admission, without significantly increasing ED LOS, ED representation rate, ischaemic stroke or mortality rates. Future research should focus on how these findings can be replicated in other settings, including rural centres without specialist cardiology services.

More individualised care can now be investigated to consider whether there are particular patient factors which predict spontaneous reversion to SR, and therefore a more nuanced pathway could be developed.