A study published this week suggests that stents placed in arteries leading to the heart have not been shown to cure chest pain (Lancet, Nov 2, 2017). Placing stents in people who have heart pain from narrowed arteries and giving them medication is not more effective in relieving pain than just giving them medication and no stents. Stents do help to prevent the heart muscle from dying when put in place within the first few hours after the start of a heart attack. If stents are placed in the heart arteries several hours after the heart attack starts, it can be too late if the heart muscle, deprived completely of oxygen for more than a couple hours, has already died.
The Study Doctors enrolled 230 patients with chest pain while exercising (stable angina) and narrowing of one artery leading to their hearts. All of the patients were given medications for six weeks to help relieve their symptoms. Then in all of the patients, doctors inserted a catheter through the leg or wrist arteries up to the narrowed artery leading to the heart. Half of the patients were given stents and half did not receive stents. The patients and their doctors were not told whether or not they had received a stent. Compared to those who did not receive stents, those who were given stents:
• did not have a greater improvement in their chest pain, and
• were not able to exercise longer on the standard exercise tests.
Tests for Blocked Arteries The test to see whether a person has a blocked artery leading to the heart is called Coronary Computed Tomography Angiography (CCTA). The doctor inserts a catheter into a leg or wrist artery and threads it up to the arteries leading to the heart. They can see if there is any obstruction of heart arteries by looking at special x-rays. Compared with a stress test (running on a treadmill at increasing intensity until a person feels chest pain), CCTA has been shown to pick up potential heart attack victims more effectively so that the person can be treated with medication and lifestyle changes to reduce a person's chances of suffering a heart attack. However, CCTA has not yet been shown to prevent death or hospitalizations for heart disease (JAMA Intern Med, Oct 2, 2017).
Why Do Doctors Put Stents in Heart Arteries? Plaques accumulate over many years on the inner lining of arteries leading to the heart, but heart attacks are not caused by plaques that partially obstruct blood flow through a heart artery. Heart muscle must get oxygen from the bloodstream 24 hours a day. A heart attack means that a part of the heart muscle dies when blood flow to part of the heart muscle is blocked completely for more than a few hours. A heart attack occurs when a part of a plaque breaks off, the area bleeds and clots, and then the clot extends to block completely any flow of blood through that artery. Then the heart muscle has no source of oxygen and starts to die. If a cardiologist runs a tube into a completely blocked artery and opens the artery with a balloon, blood flows freely to the heart muscle and the heart muscle does not die. Then the cardiologist inserts a stent (metal or otherwise) into the previously blocked artery to keep it from closing again and the cardiologist has saved that person's life.
However, there is little solid scientific evidence of benefits from a stent placed in a heart artery that is not completely blocked. Stents are foreign bodies in an artery and they can cause other plaques to break off and form further clots to block that artery completely again. Everyone who has received one or more stents must take anti-clotting medication for the rest of his life. A stent puts a person at increased risk for forming clots that can cause strokes and heart attacks for the rest of his life. To counter this problem, medical device companies have developed stents that eventually disappear from the arteries and stents that release anti-clotting medication into the bloodstream. However, after three years in place, the bioresorbable and drug-eluting stents had higher rates of heart attacks and clot formation than the metal stents (J Am Col Cardiol, Oct 31, 2017).
Other Studies Showing Lack of Benefits from Stents
• Earlier studies have shown the same lack of benefit of putting stents in people with chest pain on exercising (N Engl J Med, 2007; 356:1503-1516).
• Stents have not been shown to reduce the risk of heart attacks, strokes, or death compared to optimal medical therapy alone with medications and lifestyle interventions in patients with stable coronary disease (Arch Intern Med, 2012;172(4):312-319 and 2007;167(15):1604-9).
• Stents have not been shown to prevent heart attacks in patients with chest pain on exercise unless a patient has severe lack of blood flow to the heart (Circulation, 2012;125(8):e412). Atherosclerosis occurs in many blood vessels, so placing a stent in one artery is unlikely to prevent heart attacks because it does nothing to improve the other narrowed arteries that were not stented.
My Recommendations Stents definitely save lives when they are placed within the first few hours after a person starts to suffer a heart attack. There is little good evidence to show that stents placed in heart arteries that are not completely blocked will decrease chest pain or prevent heart attacks. If your doctors recommend stents to treat chronic chest pain, discuss this new study with them and do your research. All people who receive stents must be on anti-clotting drugs for life because stents increase risk for strokes, irregular heartbeats, heart attacks, bleeding, kidney damage and serious allergic reactions (Report from the National Heart, Lung, and Blood Institute, 2010). More than 500,000 North Americans receive stents each year at a cost of $20,000 to 50,000 per procedure. See Too Many Stents
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