Clinical Decision Rules & Ancillary Investigations

The history, physical examination, ECG and CXR will normally allow the emergency physician to be fairly confident to achieve a diagnosis in a patient with chest pain presenting to the ED. There will still be a significant number of patients in whom the diagnosis is not clear or who require further investigations to allow safe discharge or definitive treatment.

Various studies have used a “chest pain score” (based upon ascribing positive or negative points to typical or atypical aspects of chest pain location, character, radiation, onset, and associated symptoms(17)) and then combined this with historical risk factors to generate predictive values for ruling in or ruling out an acute coronary syndrome(18,19). This approach alone has not led to sufficiently robust likelihood ratios to definitively rule in ACS (i.e. commit to specific therapies) or rule out ACS (i.e. allow safe discharge).

However, more robust scoring systems have been generated to assess risk by looking at components of the initial presentation AND by including additional factors, in particular biochemical cardiac markers. The most robustly validated risk scores are the TIMI, HEART and GRACE risk scores, the latter providing a score of future mortality(3,4,5).  These scores help clinicians to identify those who are at high risk and requiring admission and treatment, and those who are at low risk and safe to discharge (with or without appropriate follow up).

Patients who present with a history of ischaemic chest pain who have a normal examination, ECG and CXR will require further risk stratification in order to allow safe discharge from the emergency department. Such a “rule-out” strategy will involve the use of cardiac markers (e.g. troponin) and possible exercise testing. Clinical pathways which combine clinician gestalt with the admission ECG and subsequent troponin assay(s) have shown a 100% sensitivity.(16)