This is an excerpt from a lecture in the ‘Cardiac Notes’ by Assoc Professor Kas, to be presented at The Cardiac Course
One of the most important decisions we make on a daily basis if you work in Emergency Medicine, general practice or specialty practice is knowing which patient with chest pain we can send home and who we must admit.
So how many patients with Acute Myocardial Infarction(AMI) are you willing to miss?
I personally want to have a 0 (zero) miss rate, however the only way to do that is to admit everyone with chest pain and we know that’s not possible. Why? Because all our hospitals would be full within a couple of hours.
In a study by Pope et al (NEJM April 20 Vol 342:No 16:1163-1170), a multi-centre clinical trial of patients presenting with chest pain, they found that of the 10,689 patients in the study, 889 (8%) had an acute AMI. Of this group, 19 (2.1%) were sent home. Of the 966 (9%) with unstable angina, 22 (2.3%) were sent home.
So the number we often talk about as a missed rate is about 2%. We might improve on this but should aim to not do worse. How do we do this? By improving our knowledge on the so-called ‘atypical’ presentations.
So how do we go about predicting who may be having a cardiac event?
We use a combination of History (including risk factors), examination and the ECG.
Let me ask you the question, which symptoms and signs are most important?
The classic definition of central chest heaviness with radiation down the left arm, is what we all remember.
Body et al (Resuscitation Vol 81 Issue 3 March 2010, pp 281-286) conducted a prospective study of patients who presented with chest pain and then looked at the value of symptoms and signs in the diagnosis of acute coronary syndromes. The study had 796 patients of which 148 (18.6%) had an AMI.
When looking at the odds ratio of certain symptoms and signs, it is interesting to note that RIGHT arm pain radiation and pain in BOTH arms had odds ratios that were over 4 times greater than LEFT arm pain radiation. The greatest odds ratio was achieved by the symptom of DIAPHORESIS.
Do symptoms and signs differ with age?
In a study by Brieger et al (Chest Aug 2004, Vol 126, Issue 2), which looked at patients presenting with an AMI but no chest pain, found that in nearly 50% of patients, the presenting complaint was DYSPNOEA.
So, how about the ECG? How much does that help?
More on this to follow