Prevalence and presentation of patients with the chief complaint “cardiac arrhythmia” – data from a large university emergency department


 Background Cardiac arrhythmias (CA) are a common chief complaint that leads to presentation at the emergency department (ED). However, data on the underlying diagnoses in patients with CA is not well studied. Our objective was to analyse the prevalence and clinical presentation of CA in the setting of an interdisciplinary ED.Methods In this retrospective study, we included all patients admitted to our ED in the Ludwig-Maximilian University Hospital in Munich within one year with the chief complaint “cardiac arrhythmia”. Subsequently cardiac rhythm in the 12-lead electrocardiogram (ECG), clinical presentation, therapy performed in the ED and in-hospital care were analyzed.Results A total of 558 out of 36.798 visitors of the ED presented with the chief complaint of CA. 42.3% of these patients indeed showed a pathologic heart rhythm on the initial ECG. The most abundant pathological ECG diagnosis was atrial fibrillation. In the pathological ECG group 60.6% and in the sinus rhythm (SR) group 39.4% of patients had to be admitted to hospital, and 34.7% with pathological ECG underwent invasive investigations (16.8% in the SR group). Conclusion Over half of our patients showed no arrhythmia on the ED ECG. The most abundant arrhythmia was atrial fibrillation. Most of the patients were stable. However, with 49.5% admission rate was quite high. This fact illustrates the need for better outpatient management of these patients. Further chief complaint CA in the ED must not be mistaken as disease specific.


Introduction
Patients presenting to emergency rooms are often triaged using scoring systems, like the emergency severity index (1) with the purpose to identify those who need immediate medical attention on the one hand, and those who are stable and won't need many resources on the other. Still, patients' emergency management is time-critical and challenging because of patient overcrowding and staff shortage (2). The chief complaint often is the second key feature after the triage score that drives further workup -usually with prede ned algorithms for patient emergency management and workup.
One of these chief complaints is cardiac arrhythmia and particularly among the elderly, cardiac arrhythmia is a common cause of hospitalisation. In 2017, 622.000 emergency room visits with chief complaint cardiac arrhythmia were documented in the USA(3) and 574 patients per 100.000 people were admitted to the hospital due to cardiac arrhythmia in Germany (4).
So far there is little information about the patient population pooled under chief complaint cardiac arrhythmia in the emergency department setting. Therefore, our aim was to investigate the prevalence and presentation of patients with cardiac arrhythmia in the emergency room and to further analyse the proportion of patients with subsequent hospitalization.

Methods
The Ludwig-Maximilian University Hospital in Munich is one of the largest university hospitals in Germany. In this retrospective study, prevalence and clinical presentation of patients, presenting with the chief complaint "cardiac arrhythmia" to our large interdisciplinary emergency department over a time frame of 12 months was assessed.The local institutional review board approved the study (Ethikkommission der Ludwig-Maximilians-Universität München project number 18-409). The study complies with the Declaration of Helsinki. This research did not receive any speci c grant from funding agencies in the public, commercial, or not-for-pro t sectors Data was retrieved from the two hospital information systems, namely EPIAS (epias GmbH, Idstein, Germany) and i.s.h.med for SAP (Cerner Deutschland). All data was anonymized for analysis. At the time of arrival, the triage nurse assigned the triage level for each patient using the emergency severity index(1) (emergency severity index 1: patient requires immediate life-saving intervention; emergency severity index 2: high risk situation or patient confused, lethargic, disorientated or in severe pain/distress; emergency severity index 3: many resources are needed without critical vitals; emergency severity index 4: one resource is needed; emergency severity index 5: no resource is needed). Furthermore, a chief complaint was de ned for each patient.
Our 558 patients were then divided into two groups: patients with pathological ECG (atrial brillation or utter, supra-/ventricular extrasystoles, supra-/ventricular tachycardias or atrio-ventricular blocks) and patients with SR in the rst ECG at emergency room admission. In addition, necessity for hospital admission, acute medical treatment and necessity for invasive workup and treatment was analysed and compared. Moreover, a possible correlation between chief complaint in the emergency room and the principal diagnosis of admitted patients was examined by reference to the ICD Codes.
For statistical analyses GraphPad Prism 8.0 was used. Categorical data were presented as percentages together with or without the sample size. For comparison of categorial data the Fisher's Exact test was used. All numerical variables in baseline characteristics were shown as mean ± standard deviation (SD). As none of the data showed normal distribution, the Mann-Whitney-U-Test was used for statistical signi cance testing. The signi cance level for all tests was set to 0.05.

Results
In the de ned period from November 2016 to October 2017 36.798 patients attended our interdisciplinary emergency room. Out of these 10.854 were medical patients. Among these, 661 (6.1%) of patients presented with chief complaint cardiac arrythmia. For several reasons, shown in Fig. 1, 103 patients had to be excluded, leaving 558 patients for the retrospective analysis.
In less than half of all patients (236/42.3%) categorized to chief complaint cardiac arrhythmia the electrocardiogram actually showed a pathologic heart rhythm, while in 322 (57.7%) patients SR was documented in the rst electrocardiogram after admission (Table 1). Patients in the pathological ECG group were signi cantly older than patients in the SR group. Diabetes as well as hypertension and hypercholesterolaemia were more often present in the pathological ECG group. Consequently, these patients were more often on statins and antihypertensive drugs than people in the SR group (Table 1).
Furthermore, ADP-receptor antagonists, vitamin K antagonists and novel oral anticoagulants were more often components of pathological ECG patients' medication compared to patients in the SR group. Accordingly, patients in the pathological ECG group more often suffered from stroke and cardiac arrhythmia in their medical history than patients with SR. Concerning vital signs at emergency room admission patients in SR group more often were hypertensive, while patients with pathological ECG more often presented with tachycardia (heart rate over 100 beats per minute).  (Fig. 2C). The most abundant ECG diagnosis of people in the pathological ECG group by a mile was atrial brillation followed by atrial utter (Fig. 3A). Patients in pathological ECG group more frequently received medication/electrolytes from emergency room physicians compared to patients with SR. The three most frequently administered substances were magnesium (62.7% in the pathological ECG group vs. 11.5% in the SR group; p < 0.0001), beta-blockers (36.0% in the pathological ECG group vs. 7.8% in the SR group; p < 0.0001) and potassium (22.9% in the pathological ECG group vs 7.8% in the SR group; p < 0.0001).
With 60.6% the admission rate was much higher in the pathological ECG group compared to only 39.4% of the SR group or the total rate of all ED patients of 48.0%. In the following analysis we refer to the patients admitted to our hospital. Most of admitted patients with cardiac arrhythmia suffered from AF/ utter (87.4%), atrio-ventricular node block (6.7%) or supra-ventricular tachycardia or ventricular extrasystoles (5.9%). The percentage of people treated on IMC or ICU was comparable in both groups. (12.7% in pathological ECG group vs. 11.2% in SR; p = 0.4308; Fig. 3B). Duration of the hospital stay did not differ among groups with 7.7+/-7.4 days in patients with SR and 8.0+/-7.6 days in patients with arrhythmia (p = 0.1372). Fortunately, no patient of our in-hospital group died.
In the pathological ECG group 34.7% (n = 82) underwent invasive investigations. 45.1% of these patients underwent coronary angiography with 14.6% needing a percutaneous coronary intervention (PCI). Another 45.1% underwent cardioversion and in 31.7% an electrophysiological examination was conducted (Fig. 4A). In this cohort ablation most frequently was conducted for atrial utter 53.9% followed by atrial brillation 11.5% (Fig. 4B). One sixth of the patients with SR (n = 54, 16.8%) underwent invasive investigations. Most of these patients underwent a diagnostic coronary angiography (89%) and in about half of these cases a PCI was necessary (42.6%). In addition, 16.7% in this group underwent an electrophysiological examination (Fig. 4A). Here particularly atrial utter (33.3%) and AV-nodal re-entrant tachycardia/focal atrial tachycardia/Wolff-Parkinson-White syndrome (55.6%) were treated (Fig. 4B). Far and away the most frequent principal diagnosis according to ICD10-Codes of the in-hospital cardiac arrhythmia patients were cardiac arrhythmias with 69.6% followed by heart failure with 4.8% and diagnosis subsumed under the topic coronary artery disease with 4.0% (Table 2). In the SR group cardiac arrhythmia also was the most frequent principal diagnosis with 29.2% followed by coronary artery disease with 19.2% and heart failure with 6.7% (Table 2).

Discussion
Patients in our study were divided into two groups: patients with SR and patients with cardiac arrhythmia in the rst electrocardiogram at emergency room admission. Interestingly 57.7% of patients had SR. These patients constituted the healthier group with younger patients having less cardiovascular risk factors and shorter medical history. Additionally, these patients more often came self-paced to the emergency room and were categorized in a higher emergency severity index state than patients with cardiac arrhythmia more often sent by panel doctors and getting lower emergency severity index degrees at admission consuming more resources and tolerating shorter waiting time in the emergency room.
Altogether two third of patients with cardiac arrhythmia had to be admitted. In the SR group, only 39.4% were admitted, a fact also reinforcing these patients to be healthier. For patients in this group with symptoms consistent with cardiac arrhythmia it is important that emergency room physicians recommend an outpatient cardiological follow-up with prolonged electrocardiogram-monitoring, to yet get the chance to detect cardiac arrhythmias (5). Especially because a signi cant number of patients in the SR group already suffered from stroke and therefore diagnosing atrial brillation is particularly important to reduce the risk of repeat stroke. This is a challenging task for licensed cardiologists and the duration of electrocardiogram monitoring is still discussed in respect of cost-bene t calculation (6)(7)(8). Altogether 242 (43.4%) patients in our cohort had a medical history of cardiac arrhythmia (anamnestic or con rmed by electrocardiogram in the past). Especially in the pathological ECG group the percentage was high with 61.2%. This fact emphasizes the need for better outpatient support of these patients with repetitive rhythm analysis and best medical supportive care even though this might be challenging and timeconsuming in some cases. Perhaps new available user-owned devices can simplify this process (9).
However, only close-mashed outpatient care can reduce the frequency of emergency visits and admission to hospital of patients with cardiac arrhythmia. In this manner resources could be saved, and costs could be reduced.
Atrial brillation was the most abundant diagnosis in patients in the pathological ECG group. This nding is in line with data from the US where annual ED visits for AF increased by 30.7% from 411.406 patients in 2007 to 537.801 patients in 2014(10) -an unsurprising fact with AF being the most frequent arrhythmia in adults (11). The incidence and prevalence of AF is driven by aging of people and presence of different risk factors for example hypertension also re ected in the baseline characteristics of our patients (12).
Most patients in the pathological ECG group suffered from AF or utter and the two most frequent mentioned symptoms were palpitations and dyspnoea comparable with studies dealing with symptoms in several thousand AF patients (13)(14)(15)(16). In our cardiac arrhythmia cohort chest pain took the third place of symptoms. In the former mentioned AF studies fatigue was under the third most frequent mentioned symptoms. This might be explained by the fact that patients in our study not only suffered from AF but also from some other arrhythmias.
Chest pain was the second most common symptom in patients with SR after palpitations. Compatible with the symptoms the most frequent intervention for patients in SR group was heart catheterization with and without PCI and for patients in pathological ECG group cardioversion and electrophysiological examination with or without ablation for several arrhythmias.
Encouragingly, no patient of our in-hospital group died while Mockel et al. reports a higher in-hospital mortality of patients with other chief complaints like chest pain (0.9%), abdominal pain (5.1%) and dyspnea (9.4%). Accordingly, only 2.8% of all SR patients and 3.0% of all cardiac arrhythmia patients in our cohort were admitted to ICU compared to 18% of patients with dyspnea and about 11% with chest pain in the former mentioned report (17). The analysis of in-hospital patients' principal diagnosis "cardiac arrhythmia" and therefore the underlying disease according to the ICD10-Codes showed a good correlation with the selected chief complaint in the emergency room for patients with arrhythmias in the electrocardiogram with 69.6% but only for 29.2% of patients with SR in the rst electrocardiogram. So chief complaints in the emergency room are a good tool to preselect patients but must not be mistaken as disease speci c and therefore physicians should not be misguided by chief complaints in the evaluation of patients in the emergency room.
As a retrospective data analysis this study has some limitations. Since ICD Codes of ambulatory patients are monetary irrelevant in Germany, they were not audited by health insurance and where thus considered not reliably enough for analysis in our study.

Conclusion
In summary, we could show that over half of all patients pooled under chief complaint cardiac arrhythmia in the emergency room showed SR on electrocardiogram at admission. The most abundant arrhythmia was atrial brillation. With 60.6% the hospital admission rate was quite high but patients presenting to the emergency room with chief complaint cardiac arrhythmia were rarely in critical condition. As a high percentage of our cohort had a history of cardiac arrhythmia a better outpatient management is needed for these patients to reduce emergency room visits and save resources. Chief complaint "cardiac arrhythmia" in the emergency room showed a good correlation with the underlying disease for in-hospital patients with arrhythmia in the rst electrocardiogram only, the chief complaint seems not speci c and physicians may not be misguided in the patients' management in the emergency room.