A final report on the official outcomes of the ISCHEMIA Studies was recently published online (New Engl J of Med, Mar 30, 2020). In these studies, 5179 patients with moderate to severely blocked arteries were randomly assigned to receive:
• medical therapy alone, or
• stenting or bypass surgery.
In four years of follow-up, the death rates of the two groups were essentially the same. This suggests that most people with clogged arteries do as well with medication and lifestyle changes as they do after undergoing invasive procedures to reopen their blood vessels such as stents, balloon angioplasty or bypass surgery.
Although these results are still somewhat controversial, Drs. James Salazar and Rita Redberg of the University of California San Francisco have written an editorial that should serve as a wake-up call to doctors and heart patients (JAMA Intern Med, Sept 21, 2020). They note that many stents are inserted into arteries leading to the heart without proven benefits to the patient of:
• preventing a future heart attack,
• prolonging life, or
• preventing chest pain.
Inappropriately placed stents may even be shortening lives because stents permanently increase risk for future clots, the main cause of heart attacks and strokes. The authors conclude that “Despite this, patients with stable angina undergoing PCI (stents) have erroneous expectations, including a decreased risk of future heart attacks and reduced mortality, and are under-informed or uninformed of potential complications.”
When Stents Can Help to Prevent Heart Damage
Most doctors agree that heart attacks are not caused by narrowed arteries. They are usually caused by a sudden complete obstruction of blood flow to a part of the heart muscle that deprives it of oxygen. This can cause pain and if allowed to continue for more than a few hours, will cause that part of the heart muscle to die. If the patient does not die, the prolonged lack of oxygen causes that part of the heart muscle to be replaced by scar tissue, which increases risk for irregular heartbeats and heart failure.
If doctors can open the blocked heart artery within a few hours after the start of a heart attack, the heart muscle may not die. Once the blocked heart artery is opened, the doctors must do something to keep it open, or the artery will quickly close down again, so they insert a stent inside the artery to keep it open. However, the stent helps to prevent a heart attack only if it is inserted within a few hours after the artery is blocked. After 4-10 hours, the part of the heart muscle without oxygen is already dead and opening the artery will not bring the heart muscle back to life.
A doctor can diagnose a heart attack with tests for chemicals such as troponin that are released by dying heart muscle, and with an electrocardiogram that suggests that the heart muscle is suffering from lack of oxygen. If a stent is inserted at that time, the doctor can prevent a part of the heart muscle from dying. However, if the stent is inserted when a person is not suffering from an acute heart attack, it is not likely to prevent future heart attacks or reduce the risk of death (N Engl J Med, 2020;382(15):1395-1407; JAMA Intern Med, 2014;174(2):232-240).
Other Studies on Stents vs Medical Management
• Patients with stable angina who had stents gained no significant symptom relief or improvement in quality of life compared with patients who had a placebo procedure. Stenting did not relieve stable angina symptoms (JAMA, Dec 26, 2017;318(24):2419).
• A 15 year follow-up showed that people with heart pain caused by blocked arteries who received stents did not live longer than those who did not receive stents (N Engl J Med, Nov 12, 2015;373(20):1937-46).
• A study of 2287 patients with stable heart disease found that stents were not more effective than medical management in preventing death after both 4.6 and 15 years (N Engl J Med, Nov 12, 2015;373(20):1937-46).
• In studies of 1,557 patients followed for an average of three years, those with stents were only slightly less likely to die than those who received just medical management (Am J Cardiol, May 1, 2015;115(9):1194-9).
• In five studies of 4064 patients with proven plaque obstruction of blood flow to the heart, followed for up to five years, death rates, non-fatal heart attacks, and heart pain were the same for those who received stents plus medical management and those who received only medical management (JAMA Intern Med, Feb 1, 2014;174(2):232-40).
Just about everyone in the field agrees that stents save lives when inserted within a few hours of the start of a heart attack. There is still controversy over whether doctors should put stents in heart arteries at other times. The majority of evidence is that in the absence of an acute heart attack, stents are not superior to sound medical management in preventing future heart attacks or relieving chest pain. Of course, your decisions depend on consultation with your doctor and specialists, not on articles that you have read. For a detailed list of risk factors for heart disease, lifestyle changes to help prevent and treat heart disease, and a discussion on statin drugs, see my report on Heart Attack Prevention