A major cardiac study suppressed mortality data related to stents

There are many competing interests involved in high profile medical studies and data can be crunched, endpoints manoeuvred to suit various agendas.

Myupchar December 16, 2019 14:36:20 IST
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A major cardiac study suppressed mortality data related to stents

A major cardiac study, EXCEL, has been caught in a storm since BBC ran a segment on 9 December alleging that the researchers had suppressed vital data which would have changed the complexion of its conclusions. The study randomly divided the treatment regimen of 1905 patients suffering from left main coronary artery stenosis (which involves a narrowing of the main blood vessel of the heart) into surgical intervention (open-heart surgery) and stenting (non-surgical procedure). The primary health outcomes that the study examined were death, myocardial infarction (heart attack) and stroke. The three-year and five-year data suggested that health outcomes were similar for both interventions. 

A major cardiac study suppressed mortality data related to stents

Representational image. Image source: Getty Images.

Different definitions of heart attacks 

The heart of the controversy — and this may come as a surprise to most people — involves the definition of ‘heart attack’. EXCEL was supposed to release findings based on two theories - the ‘universal definition’ which looks at blood tests and heart monitor readings to ascertain anomalies, and the ‘SCAI method’ which looks just at blood tests. But they withheld the conclusions based on the universal method.

Higher difference in mortality rates than suggested

BBC found that according to the universal definition of MI (myocardial infarction), those who had received stents had an 80% higher likelihood of a future heart attack when compared to the open-heart surgery group. Moreover, after 5 years, 10% of those who underwent surgery died as opposed to 13% who got stents. These are significant differences according to David Taggart of Oxford University who was involved with the study. He vehemently criticised the conclusions of the study for neglecting to highlight the significant differences in mortality rates and for suppressing the data in his interview with BBC. The people involved in the study were in their late sixties and had low to moderate variations of the disease. Taggart added that those who did receive stents in this state likely had a subsequently lower quality of life. He has since removed his name from the paper published in the New England Journal of Medicine (NEJM).

This finding does not mean that stents are harmful interventions. In cases where the patient is older and unable to bear the severity of open-heart surgery, stents can be a life-saving option. Symptom relief from the pain of heart disease such as severe angina is regularly reported post stenting and the procedure can raise the standard of life when used appropriately. 

The study framed recommended practices

Another major concern expressed by Taggart and BBC is that the Data and Safety Monitoring Board (DSMB), which publishes guidelines and recommends clinical practices for medical professionals, allegedly expressed concerns on seeing the data attributing higher mortality to stents. According to BBC, the DSMB suggested publishing guidelines highlighting the findings but were discouraged by the EXCEL panel to do this. Similarly, NEJM suggested underlining the differences in mortality but EXCEL again prevailed. No proof has been provided to support these claims. 

Professor Nick Freemantle, who is involved with DSMB, told BBC that the guidelines would have most certainly been different had the data on ‘universal definition’ been known. 

The European Association for Cardio-Thoracic Surgery (EACTS) which represents surgeons has formally rescinded its support to the findings of the study. 

The tug of war between cardiologists and surgeons

The controversy has a lot to say about how modern science is funded. Abbott, the American pharmacological giant, funded this study. All four of the primary researchers acknowledged receiving personal money from the funders. One of the researchers went on to receive a big post from Medtronic, the US-based healthcare company that makes stents. 

Abbott denies any wrongdoing in the study, and while it is difficult to assess this claim, the biases involved in medical studies need to be scrutinized - especially when huge financial interests are involved. Some argue that funding is vital to incentivize research and promote medical science, but others, are wary of the compromises made along the way. 

In fact, the European Society of Cardiology (ESC) which is involved in the industry of stents, has stated that regardless of these new findings, the basic parameters and data from the study are sound and they will not change their guidelines. The SCAI method has been used in other major studies and is considered to be a sound method. 

Dr Ajay Kirtane, MD, SM, associate professor of Medicine at Columbia University, New York and Director of the Cardiac Catheterization Laboratories at NewYork-Presbyterian, was not involved in the study, told TCTM, “The choice of MI definition is more complex than it might appear… My view, not being involved in the trial, would be to allow time for the trial investigators to respond in an open and honest way so we can understand all the issues that have been raised.”

Rebuttal

The EXCEL panel responded to the EACTS dissension. They said sufficient data was not available to disclose conclusive results based on the Universal definition as the study was constrained by on-site costs and couldn’t provide all imaging tests and biomarker assessments like cardiac troponin (required for the universal definition of MI). 

Additionally, the panel debunked claims that DSMB was pressured into not publishing any findings; they claimed that the DSMB was given access to all data and constantly gave their consent in continuing the trial. Finally, EXCEL also said all-cause mortality was a weak secondary indicator and the data was not powered to arrive at authoritative conclusions regarding it. 

There are many competing interests involved in high profile medical studies and data can be crunched, endpoints manoeuvred to suit various agendas. The key, however, is a healthy debate. EXCEL might have unwittingly become a study that will yield uneven but ultimately constructive results.

For more information, please read our article on Heart Attack.

Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health.

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