Doctor's Review: Medicine on the Move

August 16, 2017

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The 2012 CCC took place blocks away from Nathan Phillips Square in downtown Toronto.

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2012 Canadian Cardiovascular Congress

Arresting developments

There are medical meetings that disseminate knowledge, and then there are those that change practice. With nine new guidelines or guideline updates, the Canadian Cardiovascular Congress, held October 27 to 30 in the Metro Toronto Convention Centre, fell into the latter category. If you skipped it, you may have some reading to catch up on.

There were guideline updates on atrial fibrillation and stroke prevention; on antiplatelet therapy; on dyslipidemia; and on acute and chronic heart failure. There were also new Canadian guidelines on pediatric heart failure and cardiac resynchronization. And the Canadian Cardiovascular Society laid out its positions on imaging radiation exposure, transcatheter aortic valve implantation, and remote monitoring of cardiovascular implantable electronic devices.

Perhaps the biggest single change in all these guidelines is that warfarin is now definitively on the way out. Dabigatran, rivaroxaban and apibaxan (approved since the conference ended) are the new anticoagulants of choice for stroke prevention in atrial fibrillation.

In antiplatelet therapy, the Canadian Cardiovascular Society now ranks clopidogrel behind the more bioavailable prasugrel and ticagrelor, the latter of which has been first choice in Europe for some time. Patients receiving dual antiplatelet therapy should take ASA 81 mg, the guidelines suggest. There are also several changes to risk calculation and treatment selection in dyslipidemia.

Pediatric heart failure

One set of guidelines that has never before existed in Canada deals with heart failure in children, an underappreciated problem plagued by avoidable misdiagnosis. About one case in two ends in death or for a lucky few, heart transplant.

“Providing guidance in this area may help to solve one of the biggest challenges we have: that children with heart failure are usually not recognized early and treated effectively,” said guideline chairman Dr Paul F. Kantor, head of pediatric cardiology at the Stollery Children’s Hospital, University of Alberta.

“Often children are brought to the emergency room with shortness of breath and some cough and are thought to have asthma, when in fact they have very severe heart failure,” said Dr Kantor. “The clues of a very unusually fast heart rate and low blood pressure are sometimes overlooked and these children will be sent home with a puffer for their breathing problems, which are actually due to heart failure.”

Cardiomyopathy, often genetic in origin, should be excluded when a child presents with unexplained rapid heart rate or rapid breathing. Children who present with abdominal pain and vomiting and have signs of poor circulation should prompt consideration of myocarditis. Echocardiography should be performed by a pediatric specialist, urged Dr Kantor. “It’s very important that these children receive expert care because they tend to deteriorate rapidly. They need to be admitted to a hospital that has pediatric expertise and be evaluated by a children’s heart specialist, with echocardiography done by that specialist.”

Dr Andrew Krahn of the University of British Columbia presented a study on cardiac arrests among the young, analyzing 176 sudden deaths that struck down Ontarians aged 2 to 40 in 2008.1 The findings dispel the myth that such deaths are closely linked to sports and exercise, with 72% occurring at home. Only 33% of pediatric sudden cardiac deaths, and 9% of young adult deaths, occurred during exercise of any kind. “Put it this way,” explained Dr Krahn: “If you have a 13-year-old kid who is not the star athlete who dies at home watching TV, it doesn’t make the news. But if the same kid is a high school quarterback or hockey star, then it’s covered.” He advocates careful screening of young people who faint.

Shot to the heart

The recent American Heart Association conference heard research suggesting that the winter spike in cardiovascular events is actually due to a spike in viral respiratory illnesses.2 This notion cropped up again at CCC 2012, with two research papers showing protective effects from flu vaccination. A small meta-analysis led by Dr Jacob Udell of Women’s College Hospital and the University of Toronto found that flu vaccination reduced cardiovascular events by 50% and all-cause death by 40% in the 12 months following vaccination, compared to placebo, in a population in which about half had recognised heart disease.3 Obviously this goes far beyond any effect that could be expected by merely reducing flu cases, and argues for anti-inflammatory pleiotropic effects from the vaccine itself. Likewise, Dr Ramanan Kumareswaran of Sunnybrook Health Sciences Centre and his team found a trend towards fewer shocks in patients with implantable cardiac defibrillators in the season following flu vaccination.4

The effect size in the former study elicited skepticism from all quarters – even the authors – but all agreed that a large North American study is needed. We haven't heard the last on this issue.

Road sense

CCC 2012 hosted a highly entertaining debate on reporting serious medical conditions to the Ministry of Transportation as most Canadian provinces require – a debate that ended with both speakers and almost the entire audience cheerfully agreeing that such laws are useless and should largely be ignored. Dr Christopher Simpson of Queen's University in Kingston laid out a convincing argument that reporting conditions such as syncope would prevent almost no accidents – Ontario data shows that only 1.6% of accidents involve a driver with a serious medical condition and it usually isn't a factor even then. Physicians would have to report 18,000 cardiac patients to save one life. "Can you think of a single drug that you would give to 18,000 patients, which would cause side effects in every one of them, to save one life?" he asked. His debate opponent, Dr Carlos Morillo of McMaster University – who wrote the CCS 2003 guidelines on assessing fitness to drive in the cardiac patient – tried dutifully to counter these arguments but his colleagues knew he was only playing devil's advocate and in fact largely agrees with Dr Simpson. It has already been shown in epilepsy that mandatory physician reporting just drives patients to conceal their illness and miss vital treatment. And so the current, common sense arrangement is likely to be maintained: very few patients will be reported and almost no physicians will be punished for failure to report.

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