FOAM4GP Map – Cardiac stress testing

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 CardiologyLink

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?

Myocardial Perfusion results

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

What to do?

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!)

Cheers, Rob.

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6 thoughts on “FOAM4GP Map – Cardiac stress testing

  1. Hi Rob,
    Thanks for your great summary.

    This quote is from ‘Uptodate’ and the AHA guidelines regarding CTCA which was not on your list:

    “Noninvasive coronary angiography is reasonable for symptomatic patients who are at intermediate risk for coronary artery disease after initial risk stratification, including patients with equivocal stress test results”

    A recent article in MJA is even more positive about CTCA – Med J Aust 2012; 196 (4): 246-249

    I reckon if I was a sun-tanned bloke from the land with more to do than travel to and from the big city every week I reckon I would surmise the following:

    Stress ECG – a test that will end up equivocal while I wait for an angiogram
    Stress Echo – a test that will give some excellent information about my ejection fraction and mild mitral regurgitation but not visualise the plaque about to rupture in my LCA
    Perfusion Study – a test that will give hazy and imprecise (albeit colourful) images representative of myocardial perfusion in institutions that offer perfusion scanning of the myocardium….once again I may need an angiogram
    Angiogram – a night in hospital with a sore groin but a clear picture of whether I need to change my lifestyle or not and exactly how big that LCA plaque is…they might even sneak in a stent depending upon several patient and hospital factors…
    CTCA – 98% sensitivity, 88 % specificity compared to angiogram and the same (yes same!) radiation load. Walk in, walk out, back home to check the cattle that afternoon. And…if my coronaries are a bit dodgy then it can help plan the CABG or stent. Less cardiology bills, less trips to the big city, more knowledge sooner…

    Random thought while typing – ‘If the sprinklers aren’t working in the back paddock you check whether the irrigation pipe is blocked not whether whether the cotton crop is still growing!!’ Perfusion scanning, stress echo and stress ECG appear to be surrogate markers for IHD and the studies showing how they compare to invasive angio and CTCA seem to support this.

    I think the format you put forward is good Rob.

    Find a cardiologist who will refer your patient for a CTCA. If it is clean get him to do the lifestyle stuff regardless as this will decrease his likelihood of cancer and depression which may be his real life threats.

    Regards

    Daryl Pudney

    • Hi Daryl,

      Brilliant comments thanks very much! I have tried not to reference UpToDate too much because most readers will not be able to access it (but have my own access and it is invaluable).

      The CTCA is not something I knew alot about. I have now had a look at some of the literature and it looks brilliant?! I am looking for the catch? I will ring my local hospital later in the week and see if they do it and if I can access it. If this is the case then I might organise that and then I will add another section onto the FOAM Map for CTCA.

      ADDIT: I have had a look at the MBS and it says that only a specialist can order it? Is this another case of GP’s being unable to order the most appropriate test for the clinical situation? (E.g. Radicular back pain MRI vs CT?) I will dig further if I can but this does put a dampener on the whole idea. I might have to then refer him to the cardiologist (who he cannot afford). I have not had a lot of success convincing specialists to allow me to order investigations in their name?

      Just a last question. Is your background GP Daryl or Cardiology or something else?
      Thanks again for the insights – this is what I want to generate discussion like this
      Cheers, Rob.

      • Hello Rob
        Not smart enough for cardiology myself but cardiological screening is an interesting debate because there is a lot of research and lots of disagreement. It is also interesting in Australia because we have a two tiered health system and an infinitely tiered geography. What is most appropriate depends upon context more than evidence.

        If your local cardiologist has a stress echo in his rooms and looks after your patients (both public and private) and you can call him/her direct when your worried about old Mrs Jones’ new murmur on a Friday arvo when there is sick kid in the waiting room then stress echo it is!! Relationships help your patients if you hang out with the right crowd.

        I wouldn’t lament not being able to get the most evidence based test for your patient. Just understand the limitations of the ones you have available.

        Personally I think CTCA makes sense and is coming however the take up of newer technology in medicine seems to lag other fields of human endeavour. CTCA is very patient friendly and it is what I would want. Maybe we can divert some of the funds from subsidising statins to roll out some more access to scanners?

        Regards
        Daryl

      • Hi Daryl,

        If you’re smart enough to be a GP then you’re smart enough to do anything – I think it’s one of the hardest specialties in regards to uncertainty, diagnostics, epidemiology, and management. Hard to be an expert on everything (but with my adult ADHD I am going to try!)

        The comment on context vs evidence is very very true and we shouldn’t forget that. You treat the patient in front of you based upon the patient in front of you – we use evidence to guide us but patients rely upon our common sense and intelligence to work out when to apply it and when not to.

        I look forward to seeing CTCA on the MBS for GPs. Like all CT’s, they are better used in the older population where radiation side effects are less likely to apply.

        Thanks for the thoughts Daryl,
        Cheers, Rob.

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