Tag Archives: Christchurch Hospital

An even quicker way to rule out heart attacks

The majority of New Zealand emergency departments look for heart muscle damage by taking a sample of blood and looking for a particular molecule called a high-sensitivity troponin T (hsTnT).  We have now confirmed that rather than two measurements over several hours just one measurement on arrival in the ED could be used to rule out heart attacks in about 30% of patients.

What did we do?

We think this is a big deal. We’ve timed this post to meet the Annas of Internal Medicine timing for when our work appears on their website – here.  What we did was to search the literature to find where research groups may have measured hsTnT in the right group of people – namely people appearing in an emergency room whom the attending physician thinks they may be having a heart attack. We also required that the diagnosis of a heart attack, or not, was made not by just one physician, but by at least two independently.  In this way we made sure we were accessing the best quality data.

Next I approached the authors of the studies as asked them to share some data with us – namely the number of people who had detectable and undetectable hsTnT (every blood test has a minimum level below which it is said to be “undetectable” in hsTnT’s case that is just 5 billionths of a gram per litre, or 5ng/L).  We also asked them to check in these patients if the electrical activity of the heart (measured by an electrocardiogram or “ECG”) looked like there may or may not be damage to the heart (a helpful test, but not used on its own to diagnose this kind of heart attack).  Finally, we asked the authors to identify which patients truly did and did not have a heart attack.

What did we find?

In the end research groups in Europe, UK, Australia, NZ, and the US participated with a total of 11 studies and more than 9000 patients.  I did some fancy statistics to show that overall about 30% of patients had undetectable hsTnT with the first blood test and negative ECGs.  Of all those who were identifiable as potentially “excludable” or “low-risk” only about 1 in 200 had a heart attack diagnosed (we’d like it to be zero, but this just isn’t possible, especially given the diagnosis is not exact).

VisualAbstract AnnalsIM 170411

Pickering, J. W.*, Than, M. P.*, Cullen, L. A., Aldous, S., Avest, ter, E., Body, R., et al. (2017). Rapid Rule-out of Myocardial Infarction With a High-Sensitivity CardiacTroponin T Measurement Below the Limit of Detection: A Collaborative Meta-analysis. Annals of Internal Medicine, 166(10). http://doi.org/10.7326/M16-2562 *joint first authors.

What did we conclude?

There is huge potential for ruling out a heart attack with just one blood test.  In New Zealand this could mean many thousands of people a year can be reassured even more swiftly that they are not having a heart attack. By excluding the possibility of a heart attack early, physicians can put more effort into looking for other causes of chest-pain or simply send the patient happily home.   While not every hospital performed had the same great performance, overall the results were good.  By the commonly accepted standards, it is safe.  However, we caution that local audits at each hospital that decides to implement this “single blood measurement” strategy are made to double check its safety and efficacy.


Acknowledgment: This was a massive undertaking that required the collaboration of dozens of people from all around the world – their patience and willingness to participate is much appreciated. My clinical colleague and co-first author, Dr Martin Than provided a lot of the energy as well as intelligence for this project. As always, I am deeply appreciative of my sponsors: the Emergency Care Foundation, Canterbury Medical Research Foundation, Canterbury District Health Board, and University of Otago Christchurch. There will be readers who have contributed financially to the first two (charities) – I thank you – your generosity made this possible, and there will be readers who have volunteered for clinical studies – you are my heroes.

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Cheesecake files: A world second for heart attacks

Going to the Emergency Department with chest pain no longer means an almost certain night in hospital.  Friday saw the publication online of our randomised controlled trial comparing two different strategies to rapidly rule-out heart attacks in people who present with chest pain to hospitals.  Here’s a précis:

What’s the problem?

  • Chest pain is common – 10% or so of presentations to ED are for chest pain.
  • Heart attacks are not so common – only ~10-15% in NZ (and less overseas*) actually have a heart attack.
  • It is devilishly difficult for most chest pain to rapidly rule out the possibility of a heart attack.
  • Consequently, most people get admitted to hospital (in 2007 93% of those presenting with chest pain).

But – led by Dr Martin Than in Christchurch and an international group including Dr Louise Cullen in Brisbane – a series of observational studies and one randomised control trial have resulted in a gradual increase in the proportion discharged.  The trial was the first of its kind, it compared standard practice at assessing chest pain to a purpose built accelerated diagnostic pathway (ADP), which we called ADAPT.   In that study 11% of patients in the standard practice (control) arm and 19.3% in the ADAPT ADP arm (experimental arm) were discharged home from ED within 6 hours.  A great improvement which led to that ADP being adopted in Christchurch hospital.

So why another study?

Two reasons: First, 19% still means that there are many patients being admitted who potentially don’t need to be in hospital.  Second, the ADP was based around a risk assessment tool designed to rule-in heart attacks rather than rule-out.  In the meantime, the team had constructed a purpose build risk assessment tool that in observational studies looked like it could rule out 40-50% of patients.

What is the study just published?

The world’s second randomised controlled trial of assessment of chest pain compared the ADAPT ADP in use (now the control arm) with a new ADP based on the new Emergency Department Assessment of Chest pain Score (EDACS)[the experimental arm].  The only difference between the two arms of the study was the risk assessment tool used. The tool gave a risk score. Patients with a low score, no unusual electrical activity in the heart, and no elevated heart muscle injury proteins in either of two blood samples measured 2 hours apart, were considered low risk.

An important aspect of the study was that it was pragmatic.  This means that the doctors didn’t have to follow the ADP and could decide to send a patient home, or not send them home, based on any factors they thought clinically relevant.  This makes it very tough to run a trial, but it makes the trial more “real life.”

What were the results?

558 patients were recruited.  They all volunteered and are marvellous people.  I love volunteers.

The primary outcome was the proportion of patients safely discharged home within 6 hours.  We assessed safety by looking at all medical events that happened to a patients over 30 days to check to see if any patients discharged home had a major cardiac event that could potentially have been picked up in the ED.

34% of the control arm and 32% of the experimental arm were discharged within 6 hours.  In other words, there was no difference in early discharge rates between the two arms.  The surprising feature of this is that between 2012/3 (when the first trial was run) and 2014/15 the proportion of patients the first ADP ruled out increased from 19% to 34%.  This was unexpected, but pleasing. There were no safety concerns with any patients.

The secondary outcome was simply the proportion each arm of the study classified as low risk (ie not considering whether this led to early discharge or not).  The control (ADAPT ADP) classified 31% and the experimental (EDACS ADP) 42%.  This was a real and meaningful difference which suggests that there is “room for improvement” in early discharge rates as the clinicians become more familiar with the EDACS ADP.

Since 2007 in Christchurch hospital over three times more patients who present with chest pain can be reassured from within the ED that they are not having a heart attack and discharged home (see the infographic).EDACS infographic v2

What was your role?

My role: I managed aspects of the data collection for the later 2/3rds of the patients recruited, did the statistical analysis and co-wrote the manuscript.  In reality, there were a lot of people involved, not least of whom were the wonderful research nurses and database manager who did a lot of the “grunt work”.

What now?

Over the last year all EDs in New Zealand have implemented or in the process of implementing an accelerated diagnostic pathway.  The majority have chosen to use the EDACS pathway.  I am part of a team nationwide helping implement these pathways and monitor their efficacy and safety.

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This study was funded by the Health Research Committee of New Zealand. The work was carried out with the collaboration or the University of Otago Christchurch, Christchurch Heart Institute, and the Canterbury District Health Board Emergency Department, Cardiology Department, General Medicine, and Canterbury Health Laboratories. My salary is provided through a Senior Research Fellowship in Acute Care funded Canterbury Medical Research Foundation, Canterbury District Health Board and the Emergency Care Foundation.

*Not because we have more heart attacks, just an efficient and well funded primary care sector that keeps the very low risk patients out of the ED.

**Featured Image: Creative Commons Share-Alike 3.0 http://tcsmoking.wikispaces.com/heart%20attack

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Christchurch Hospital’s latest study: IDENTAKIT-HF

If it weren’t for your kidney’s, where would you be? You’d be in the hospital or infirmary (with apologies to Fred Dagg). The heart and kidneys are not just linked by a pipe, but the health of one is very much dependent on the health of the other. Acute Kidney Injury (AKI) is a phenomenon whereby there is a sudden loss of all or some of the kidneys’ filtration ability. This can have dire immediate consequences with a greater increased risk of mortality & longer hospital stays. It can also increase the risk of developing a chronic kidney disease or even later cardiac problems. Unfortunately, AKI is devilishly difficult to detect, and therefore there are no early treatments. It is also very common – some 4-5% of all hospital patients. Those with heart failure are particularly vulnerable.

IDENTAKIT-HF is a new project all about identifying AKI biomarkers inheart failure. Two weeks ago it enrolled its first patient. It is a collaborative project involving myself, the Christchurch Heart Institute, and a biomarker laboratory in Prince of Wales Hospital, Sydney headed by former Christchurch nephrologist Professor Zoltan Endre. Not only are blood samples being taken from patients with heart failure and potential AKI, but also urine samples. This is because various novel protein markers in the urine appear to respond much more quickly to AKI than markers in the blood. It is now recognised, that not one marker, but a panel of markers is needed to identify AKI and provide information about how to target any treatments. IDENTAKIT-HF will identify the likely members of such a panel and then test if they really do identify the disease and predict its course. This will form the platform for future intervention trials to develop treatments and improve patient outcomes.

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