Clinical Case – Cardiac stress testing
72yo M retired farmer presents with intermittent episodes of chest pains over the last few years that he thought he would just ‘mention’ on the way out (“door knob” symptom). He has been getting these central vague chest pains (he reports stabbing, squeezing and difficult to describe) every month or so without radiation, trigger, associated features, and they are relieved by time (15 mins or so). He has a FHx of brother having CABG x 4 at 65yo, and 7 Aunties and Uncles all passed away from AMI’s from 50yo to 80yo. Non smoker, non drinker, no BP or cholesterol concerns and recent fasting BSL normal. Apparently has had a stress
ECG done 2 years ago which was normal and his usual doctor “has done many tests and they were all fine”. He has never seen a cardiologist. Currently not on any medications. No significant SOBOE (walks 100m+ on flat limited by OA in knees), palpitations, PND, orthopnoea, or calf swelling/claudication.
Examination added little to the consult (BP 110/75 (no postural drop), HSx2+0, chest clear, no palpable AAA, peripheral pulses normal, no P.oedema).
Clinic ECG revealed no evidence of previous ischaemia, LVH, or other conduction/rhythm abnormality.
Given this gentleman’s age and possible atypical symptomatology (chest pains) I would like to perform further stress testing on his heart. The online Framingham cardiac risk calculator puts his risk in the intermediate category (10% risk). I would like to further risk stratify him into high risk (angiogram) or low risk (risk factor modification (which in him is make him younger or remove his genetics – both difficult!). Unfortunately, he is unable to mobilise significantly on a treadmill (and his arms aren’t great either) and therefore a stress ECG is difficult. What is my next choice for investigating this gentleman’s heart?
A phone call to a local cardiologist resolved that both a stress ECHO and an MPS will give similar information and I could order whichever one I could get done sooner. Not feeling thoroughly educated on the matter I have performed a FOAMed and internet search for further information.
Question 1 – What is a stress ECHO and what can it tell me? Who is it suitable for?
Heart and Education in Heart journal has a good but detailed summary “Stress Echocardiography” (2003) – Link
For the limited in time, here is a brief overview very well written with pictures by “Heartsite” – Link
For those who prefer to watch a lecture there are two free ones here.
“The Role of Stress Echocardiography for the Evaluation of Patients with Coronary Artery Disease” Texas Heart Institute 2008 – Link
“EAE Webinar on Stress Echo” – 2011 European Society of Cardiology – Link
Having never seen one this video on Youtube was a good example of a patient undergoing Stress Echocardiography – Link
I needed an information pamphlet. Hard to find without advertising on it – Page 3 of this consent is a good handout – QHealth – Link
Having got the result, how do I interpret it? AFP “Cardiac Stress Testing” – Link – describes basically how to interpret results but otherwise hopefully the summary on the results will given instructions on what to do next (e.g. recommend for Angiogram?)
Question 2 – What is a Myocardial Perfusion Study (MPS) and what can it tell me? Who is it suitable for?
AFP has a very good summary article on MPS – Link
Free access lecture online on MPS – University of Wisconsin 2013 “Myocardial Perfusion Imaging: What BANG Do We Get for Our Buck?” – Link
Question 3 – What are the differences between the modalities?
Life in the Fastlane has a good summary on “cardiovascular performance assessment” – Link
AFP describes the differences between different cardiac stress modalities including sensitivities/specificities and MBS costs – Link
Question 4 – What is this Coronary Calcium Score I have heard talked about?
Emedicine describes the pathophysiology of the score well – Link
Inside Radiology (RANZCR) website describes the procedure to a patient – Link
Australian Doctor describes the Coronary Calcium Score and it’s recent use in risk-stratifying patients with Type 2 Diabetes in BMJ 2013 paper – Link
Australian Doctor also discusses a 2012 JAMA paper where patients were reclassified from intermediate into high or low risk based on Calcium score – Link
Medical Observer describes both sides of the debate in a discussion in March 2012 – Link
Question 5 – What did I do?!
My understanding is that this gentleman requires risk stratification into high or low risk. I looked for a long time for a guideline for patients, who unlike mine, would fall outside the Framingham (e.g. if he was a 75yo M with atypical chest pains) but struggled to find good guidance (please let me know if anyone knows of any!) It could be argued that this gentleman could just go for angiography based upon age, atypical history, and strong family history. But my guess is that a large majority of my patients over 75yo will have vague symptoms like this from time to time. Do I need to class them all as high risk and send them for an angiogram? Sounds like an expensive and not highly productive use of time or resources – not to mention patient risk.
I will discuss this with the patient and let him decide. I will expect that I will send him for a pharmacologically stress induced MPS. If this shows areas of reversible ischaemia I will be referring him to a cardiologist for angiography. If the MPS is normal, I will advise him lifestyle advice and giving him my usual safety netting information about what to do in the event of central crushing chest pain associated with either SOB, diaphoresis, nausea etc –> Call an Ambulance! That is what they are for!
Please let me know what you think. This format is experimental but could be useful for steering learning for people who are not experienced in the internet or FOAMed (or simply don’t have the time to trawl for hours!)