Chest pain — ranging from musculoskeletal chest pain to potentially life-threatening emergencies such as acute coronary syndrome (ACS), aortic dissection or pulmonary embolism — is a common presenting symptom in the emergency department, accounting for between 5 and 20 percent of all admissions. Yet clinical management is highly variable.

After initial evaluation, these patients usually are assigned to cardiac monitoring for several hours — including, but not limited to, 12-lead electrocardiography and bedside cardiac monitoring for arrhythmia and ischemia detection, as well as QT-interval monitoring. But cardiac monitors in the ED are few, and placing all patients with chest pain on monitors may block access for patients in greater need, ultimately increasing morbidity and mortality.

Studies have shown that serious arrhythmias are uncommon in monitored ED chest pain patients, and nearly 90 percent of physicians reported that they would forgo cardiac monitoring among chest pain patients if a low risk subset were identified.

A new study in the Canadian Medical Association Journal sought to validate a previous rule for safely removing patients from cardiac monitoring after initial evaluation in the ED.

The Ottawa Chest Pain Cardiac Monitoring Rule states that a patient with chest pain can be removed from cardiac monitoring on initial physician assessment if the patient is currently free of chest pain and the patient's electrocardiogram is normal or has nonspecific changes (no signs of acute ischemia, infarction, bundle branch bloc, prolonged QRS, QT or Pr interval, left ventricular hypertrophy with strain, arrhythmia or paced rhythm).

The study included 1,125 patients with chest pain, of whom 796 (70.8 percent; mean age 63.8 years, 55.8 percent male) with chest pain were assigned to cardiac monitoring at two EDs over 18 months. Baseline characteristics, findings from clinical evaluations and predictors for the Ottawa Chest Pain Cardiac Monitoring Rule were collected. The outcome was an arrhythmia requiring intervention in the ED or within eight hours of presentation to the ED and that required treatment during the patient's stay in the ED.

Fifteen (15) patients (1.9 percent) had an arrhythmia. Six patients (0.8 percent) died within 30 days of presentation to the ED, none of which were due to an arrhythmia. All arrhythmias were detected during the initial visit.

All 15 patients had an abnormal ECG as per the Ottawa Chest Pain Cardiac Monitoring Rule, and the rule performed with the following characteristics: sensitivity 100 percent (95 percent confidence interval [CI] 78.2 percent to 100 percent) and specificity 36.4 percent (95 percent CI 33.0 percent–39.6 percent). If the Ottawa Chest Pain Cardiac Monitoring Rule had been applied, 284 out of 796 patients (35.7 percent) could have been safely removed from cardiac monitoring during the initial physician assessment.

The study concluded that arrhythmias among patients presenting to EDs with chest pain are uncommon, and a substantial number of these patients are unnecessarily placed on cardiac monitors while more critically ill patients may be waiting for care. Based on these study results, recommendations include removing patients from cardiac monitors if they are free of chest pain at the ED assessment and if the ECG is either normal or shows only nonspecific changes.

That said, any patient who looks unwell or has unstable vital signs needs cardiac monitoring, regardless of the rule.