Tag Archives: Chest Pain

Cheesecake files: A new test to rule out heart attacks in just a few minutes.

Your chest hurts, you go to the hospital (good move), you get rushed through and a nurse takes some blood and measures the electrical activity of your heart.  A doctor asks you some questions.  While she does so, the blood is being tested – the results are back already! Yeah, they are negative and everything else is OK, it’s not a heart attack – you can go home.  This is the likely scenario in the near future thanks to new blood test technology which we, in Christchurch hospital’s Emergency Department, have been fortunate to be the first in the world to trial in patients. The results of our pilot study have now been published ( in a Journal of the American Medical Association (JAMA Cardiology).

About 65,000 patients a year are investigated for heart attacks in New Zealand emergency departments, yet only about 15% of them are actually having a heart attack.  New Zealand leads the world in having become the first country in the world in which all patients are assessed by an accelerated diagnostic pathway that enables rapid evaluation of the patients and can send people home after two blood tests taken two to three hours apart (see here for more).  This means many patients who once-upon-a-time would have been admitted to hospital overnight, are now able to be reassured after 4-6 hours that they are not having a heart attack and can go home.  Nevertheless, there are enormous advantages for both patient and health system to being able to come to the conclusion that the pain isn’t life threatening earlier. The cork in the bottle preventing this happening is the time it takes for a blood sample to be analysed for signs of damage to the heart. These blood tests typically take 1 to 2 hours from the time of sampling (within ~15 minutes of arrival in the ED) until the results are available for the doctor to review.  Because doctors are dealing with multiple patients at a time, their review and decisions around whether to allow the patient to go home, or to be admitted for more investigation, are further delayed.  A point-of-care test is one that happens with a small machine near the bedside and can produce results available to the doctor even while they are still examining the patient.  Until now, though, the precision of these machines has not been good enough to be used in emergency departments.  When one manufacturer told us that their new technology may now have sufficient precision we were keen to test it,  so we, in a first-in-the-world study, undertook a study in patients entering the emergency department of Christchurch hospital whom the attending doctor was investigating for a possible heart attack.

Thanks to the volunteer patients (I love volunteers) who gave some extra blood we measured the troponin concentration by this new point-of-care test (called the next generation point of care troponin I: TnI-Nx). Troponin comes from the heart muscle and is released into the blood during a heart attack. When the troponin concentrations in the blood are very very low we can be confident that the source of the patient’s discomfort is not a heart attack.  Low concentrations require a very precise measurement test. Often, a very low concentration means the patient can safely go home. In 354 volunteers we measured troponin with the TnI-Nx assay when they first came to the emergency department.  Their treatment didn’t change, and all clinical decisions were based on the normal laboratory based troponin (measured on entry to the emergency department and again 2 hours later). From the blood samples we collected and measurements we made, we could work out what could have happened if we had used the TnI-Nx results instead.

In our study the TnI-Nx troponin measurement was as good as, and possibly slightly better, than the laboratory based troponin measurement at ruling-out a heart attack. We found 57% of the patients being investigated had troponin concentrations measured with TnI-Nx below a threshold at which we could be confident that they were not having a heart-attack.  All 57 patients who were actually having a heart attack had higher concentrations.

When implemented our results may mean that instead of waiting 3-6 hours for a results, half of patients being investigated could know within about 30 minutes of arriving at the ED whether they are having a heart attack or not.  This early reassurance would be a relief to many, as well as reducing over-crowding in the emergency department and freeing up staff for other tasks.  But before we implement the new test, we must validate it in more patients – this is a study we are carrying out now.  Validation will enable us to more precisely determine a threshold concentration for TnI-Nx for clinical use which we can, with a very high degree of certainty, safely use to rule-out a heart attack.

The test also should allow people living in rural areas to get just as good care as in emergency departments because it could be deployed in rural hospital and general practices.  This would save many lengthy, worrying, and expensive trips for people to an urban emergency department.

This study was carried out by the Christchurch Emergency Department research group (director and senior author Dr Martin Than) in conjunction with the Christchurch Heart Institute (University of Otago Christchurch).  My colleague, Dr Joanna Young did much of the hard yards, and we thank our clinical research nurses and assistant for all they did to take blood samples, collect data, and lend a hand around the ED.  The manufacturer of the blood test, Abbott Point-of-care, provided the tests free of charge, but they were blinded to the results and all analysis was conducted independent of them.

How we envisage TnI-Nx may be used in the future to allow very early rule out of heart attacks

Please note – patients experiencing sudden onset chest-pain should always seek immediate medical attention.

I am fortunate to hold a Senior Research Fellowship in Acute Care sponsored by the Canterbury Medical Research Foundation, the Emergency Care Foundation, and the Canterbury District Health Board which enables me to participate in these studies.

ps.  You’ll have to read some of my older posts if you want to know why “Cheesecake files”

 

Major government health directive monitored for efficacy and safety

Last year I was fortunate to become part of a team at Christchurch hospital led by emergency care physician, Dr Martin Than. About 7 years ago in response to some local issues with how patients presenting with chest pain were being evaluated for potential heart attacks, Dr Than began a research program that investigated what clinical, demographic, and biological (blood) factors could best be used to safely and efficiently rule-out a heart attack.

Someone turning up at the doors of the Emergency Department with chest pain desperately wants to hear those reassuring words “You are not having a heart attack.” Unfortunately, for the ED staff this a very difficult conclusion to come to rapidly. As a result, around the world, as many as 90% of patients being assessed for possible heart attack end up being admitted to hospital overnight or longer, although only 20% of them end up being diagnosed with a heart attack. Obviously this is not good for the patient or the hospital – especially given tight budgets and lack of bed space. Dr Than’s work addressed the problem with a large multi-national observational study which assessed if a decision making pathway (called an accelerated diagnostic pathway or ADP for short) could increase the proportion of patients who could potentially not be admitted to hospital instead referred for some outpatient testing(1). This was further refined in another observational study which reduced the number of blood biomarkers that needed testing(2). Finally, and uniquely a randomised controlled trial of the new ADP verse standard practice was run at Christchurch Hospital. This was very successful, nearly doubling the proportion of patients who could be discharged to outpatient care within 6 hours of arriving in the ED(3). More has been done since on refining the ADP … but that is for another post.

The Ministry of Health liked what they saw as did ED physicians and Cardiologists throughout the country. This has resulted in the MOH asking all EDs within New Zealand to implement an accelerated diagnostic protocol. In doing so they will join all of Queensland, and a sprinkling of hospitals throughout the world that have recently adopted an ADP. This kind of positive outcome to local research is what every scientist dreams of, and Dr Than and his team have a right to be proud. But wait, as they say, there is more. Thanks to a Health Innovation Partnership grant from the Health Research Committee we are able to put in place a mechanism to monitor the effect and safety of an ADP at eight hospitals around New Zealand. This is where I come in, as I am collecting, collating and analysing the data for this project.   It is very exciting to be involved not only in helping implement a change of practice, but to be able to assess if that change is effective across a range of New Zealand hospitals from major inner-city hospitals to small rural hospitals, each of which has to adapt an ADP to meet their own particular circumstances. As I write Middlemore, North Shore, Wellington, Hutt Valley, Nelson and Christchurch hospitals all have new ADPs in place. Most if not all EDs will have them by the end of the year.

Some of where accelerated diagnostic pathways have been implemented.

Some of where accelerated diagnostic pathways have been implemented.

The model of observational research -> randomised controlled trial -> local implementation with further research -> mandatory national implementation -> research the effect of that change on local and national levels -> refine processes etc, is I believe a very good one and one that should be standard practice for major health initiatives. The MOH, HRC, and various district health boards that have bought into this process should be commended. There are other similar initiatives happening around the country and a look forward to when as a health consumer I can have confidence in any procedure I may face as been similarly thoroughly assessed.

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Thanks to my Acute Care Fellowship sponsors: Sponsors

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and to the grant funding body:

HRC

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References

  1. Than, M. P., Cullen, L., Reid, C. M., Lim, S. H., Aldous, S., Ardagh, M. W., et al. (2011). A 2-h diagnostic protocol to assess patients with chest pain symptoms in the Asia-Pacific region (ASPECT): a prospective observational validation study. Lancet, 377(9771), 1077–1084. doi:10.1016/S0140-6736(11)60310-3
  2. Than, M. P., Cullen, L., Aldous, S., Parsonage, W. A., Reid, C. M., Greenslade, J., et al. (2012). 2-Hour accelerated diagnostic protocol to assess patients with chest pain symptoms using contemporary troponins as the only biomarker: the ADAPT trial. Journal of the American College of Cardiology, 59(23), 2091–2098. doi:10.1016/j.jacc.2012.02.035
  3. Than, M. P., Aldous, S., Lord, S. J., Goodacre, S., Frampton, C. M. A., Troughton, R., et al. (2014). A 2-hour diagnostic protocol for possible cardiac chest pain in the emergency department: a randomized clinical trial. JAMA Internal Medicine, 174(1), 51–58. doi:10.1001/jamainternmed.2013.11362

Oh hell

Oh Hell, that hurts!  I sat down in a hurry. My first thought was “I’m having a heart attack.”  My second was “Don’t be silly you’re only 49 and probably just gobbled lunch too quickly, again.”  Jess came up to me and said “Gosh, you look pale.”  I mumbled something about a bit of pain.  It bit again, Jess noticed my grimace and said the inevitable “We should call a doctor.”  I tried to argue but to be honest, felt lousy and a little bit scared.  Before, I knew it I was bundled up off to the Emergency department.

Rule #1: Never ignore chest pain!

Rule #1: Never ignore chest pain!

As soon as I got in ED there were nurses and doctors questioning me, taking some blood, and sticking little metal electrodes all over my chest.  I later found out they were measuring in my blood something called troponin which goes up with a heart attack (well… they used the words like myocardial infarction and acute coronary syndrome … but all I cared about was whether I was having a heart attack or not).  The electrodes I learnt were measuring the electrical activity of my heart – they called it an ECG.  They told me that if either the troponin levels were high or the ECG squiggles were not where they were meant to be then I would be admitted to the cardiology ward.  They were going to repeat all the measurements a couple of hours later.  I was a little annoyed by all the questions to start with, but I soon learnt that sometimes the troponin levels are low and the ECG negative but people can still have a serious heart problem.  They use the questions to come up with a risk score which helps them make a clinical judgment.  The questions were about the usual stuff – smoking, family history of heart disease etc as well as some specifically about where the pain was, what kind of pain (mine was definitely sharp), and whether it moved to the arms or shoulders.

Pretty soon after I arrived someone came up to me who called herself a research nurse and asked if I would consider joining a study. She was lovely. She explained the study was all about trying to rapidly rule out a heart attack.  Apparently only a quarter of those presenting with chest pain actually have a heart problem needing attending too.  However, it’s difficult to tell quickly if someone is in that quarter or not and so a huge percentage of patients get admitted to hospital, usually staying overnight, and certainly costing the tax payer heaps.  Well, I’d just paid a massive tax bill so I signed up pretty darn quick.  Also, I can’t stand hospitals and so I’ll support anything that keeps me out of them!  Of course, this research wasn’t going to help me now, but who knows in the future.  Actually, for the price of another round of questions and a little more blood (fortunately they didn’t need to stick any more needles in me) it seemed a small price to “do my bit” for science… ‘All I have to offer you is blood, sweat…’

After a couple of hours and a repeat of all the tests, I was told they had all come out negative and my risk score was low.  The docs saw nothing else that rang alarm bells.  They signed me up for a treadmill test the next day “just in case” (served me right, I’d been avoiding the gym) and sent me on my way.  I felt a bit of a berk, but they were so good to me and kept reiterating that it is much much better to be safe than sorry.  Besides, I got to participate in some science which was rather cool.

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Author’s note:  Research in Christchurch Hospital Emergency Department lead by Dr Martin Than has enabled nearly a doubling of the numbers of people in whom a heart attack can be ruled out early.  I have been fortunate to join the team this year as we run a randomised controlled trial of two scoring regimes to see if one will increase the rates of safe early discharge.