The mortality of patients having undergone coronary bypass surgery is close to that of the general population. But after 10 years, it is skyrocketing.
Patients suffering from coronary insufficiency in whom drug treatments (beta-blockers, statins, antiplatelet agents, etc.) and possible angioplasties have not worked often undergo coronary bypass surgery.
It is a heavy surgery, open heart, but for which the prognosis is good. Surgical progress made over the past thirty years now gives patients who have benefited from it a survival almost identical to that of the general population.
But between 8 and 10 years after the operation, mortality increases very sharply.
62% more mortality
This is what epidemiologists at Aarhus University Hospital (Denmark) observed, thanks to a study of more than 50,000 patients operated on between 1980 and 2009, which they publish the results in the review Circulation: Cardiovascular Quality and Outcomes.
Comparing their 30-year survival to that of a cohort of 500,000 people, they found that it was almost the same for the eight years after the operation – with the exception of the first month, when it is between 20 and 25 times higher.
Then, between 10 and 20 years, it is higher by 62% in operated patients, and between 20 and 30 years, by 76%.
Return of insufficiency?
“We now have precise figures to establish prognoses, including long-term ones, for patients who have undergone bypass surgery,” explains Dr Kasper Adelborg, from the Department of Clinical Epidemiology at Aarhus University Hospital, and lead author of the study.
Researchers have formulated a few hypotheses to explain this sudden increase in risk. The progressive extension of atherosclerosis and the hardening of the walls of the coronary artery, which cause coronary insufficiency, as well as the aging of the material implanted during the surgery, are undoubtedly responsible.
Control visits could therefore be stepped up after 10 years.
What is a coronary bypass surgery used for?
When a patient suffers from coronary artery disease, it is most often due to atherosclerosis in the main coronary artery, or in one of its bifurcations.
A collection of lipids, complex carbohydrates, blood products, calcium deposits and minerals obstruct the vessels, causing its diameter to narrow and its elasticity to be lost, thus limiting blood flow.
The heart muscle, whose survival depends on the influx of blood from the coronary arteries, is then in pain and functions poorly: it is an angina pectoris or a myocardial infarction.
Coronary bypass surgery (which can be double, triple, quadruple or even quintuple) involves bypassing the narrowed portion of the coronary artery by grafting one (or more) other vessel (s) (thigh vein or mammary artery for example) downstream of the narrowing that causes insufficiency, and on the other side, to the aorta.
Circulation is then reestablished in the coronary arteries which again supply the heart muscle.
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