This study of long-term ECG recording practice at Sørlandet Hospital Arendal in the period 2017–18 showed that approximately half of patients tested were referred by a general practitioner or Accident and Emergency department and half by the specialist health service. The occurrence of 'palpitations' was the most frequent indication for testing (36 %). In patients with and without a history of heart disease or stroke, arrhythmias were recorded in 33 % and 6 % of tests, respectively, and testing led to new or altered treatment in 21 % and 5 % of cases, respectively (Figure 1).
Figure 1 Long-term ECG recordings in patients with and without a known history of heart disease or stroke at Sørlandet Hospital Arendal 2017–18.
We have been unable to find any similar studies, and it is therefore difficult to compare practice at our hospital with practice elsewhere. Figures from the Norwegian Patient Registry indicate a marked increase in the use of long-term ECG in Norway in recent years
(3). The number of such tests in our county (Aust-Agder, about 1 000 tests per 100 000 inhabitants per year) was somewhat lower than the Norwegian national average in 2018 (about 1 200 tests per 100 000 inhabitants per year). There is no overview available of geographical differences in testing rates across Norway, but use of the test is assumed to vary with factors including age composition, geography and local provision of medical services.
Performing and analysing long-term ECG recordings involves a considerable amount of work for cardiology departments, and we therefore call for clearer guidelines on who should be referred for such testing.
More than a third of all tests were performed in patients under the age of 65 with no history of heart disease or stroke. The majority of these tests (67 %) were performed after referral from a general practitioner or Accident and Emergency department, but few (3 %) had any therapeutic implications. The most common reason for referral in this group was 'palpitations' (53 %). This is a poorly defined term that probably encompasses a wide range of symptoms. Although 'palpitations' were found to predict atrial fibrillation later in life in the Tromsø study, detecting paroxysmal atrial fibrillation in otherwise healthy patients under the age of 65 has little prognostic significance
(4, 5). We therefore believe there is good reason to question today's referral practices.
Atrial fibrillation is the most common cardiac arrhythmia in adults, and was also the most frequent arrhythmia in this study
(6). Other clinically significant arrhythmias were rare. The prevalence of atrial fibrillation is increasing, and one in four 40-year-olds can expect to develop atrial fibrillation at some point in their life (7, 8). In approximately one third of patients with atrial fibrillation, the condition goes unrecognised (9). Undetected or untreated atrial fibrillation is a frequent cause of stroke (10). Prophylactic treatment with anticoagulants is therefore recommended for patients with atrial fibrillation and an increased risk of stroke (5). The risk of stroke in patients with atrial fibrillation increases with one or more of the following factors: heart failure, hypertension, age over 65, diabetes, previous stroke, vascular disease and female sex (5). At Sørlandet Hospital Arendal in the period 2017–18, the only patients to undergo long-term ECG recording with discovery of previously unrecognised atrial fibrillation as the sole indication, were those who had been admitted to the Department of Neurology with stroke. The prevalence of unrecognised atrial fibrillation was relatively high in this group (11 %), even though all of these patients had been assessed with standard ECG or telemetry in connection with hospitalisation.
The European Society of Cardiology recommends opportunistic screening for atrial fibrillation with standard ECG or pulse measurement in all those over 65 years of age
(5). Long-term ECG recording increases the likelihood of detecting paroxysmal atrial fibrillation compared with a standard ECG recording. However, there is currently little long-term ECG recording equipment available that is suitable and affordable and sufficiently easy to use for screening purposes in larger populations (11). This is likely to change in the near future, warranting discussion of screening for atrial fibrillation in selected groups.
This study has several weaknesses. It is based on relatively few patients and covers a limited geographical area. Referral practices and procedures may vary across hospitals, and population composition and patterns may have an impact on the results. All information in the study was retrieved retrospectively from patient medical records. The tests were interpreted and described by several different doctors with varying degrees of clinical experience, and the ECG recordings were not reanalysed. The study also has no follow-up data, and therefore we do not know whether any changes were subsequently made to diagnoses or treatment.
In summary, this study shows that long-term ECG recording had therapeutic implications in only 5 % of patients without known heart disease or previous stroke. No patients were referred for testing solely because of an increased stroke risk, even though these patients could potentially benefit greatly from the test. We recommend establishing national guidelines for the use of long-term ECG recording, and believe that the test should be used to a greater extent in patient groups where the results would have therapeutic and prognostic implications, such as those patients who would be considered at increased risk of stroke if atrial fibrillation were detected. The risk of stroke should be assessed as part of the anamnesis and clinical examination, prior to referral for long-term ECG recording.