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Using Shared Decision Making to Improve Erik's Hospital Stay, Part 2: Treating Afib
August 15, 2016
Atrial fibrillation (afib) is by itself usually a benign and easily treated condition. However, it does increase the risk of stroke, and that is its most concerning ramification impacting treatment options. Erik developed atrial fibrillation a few days into his hospital stay, and the ensuing recommendations by the medical team regarding how to address it lead to the most contentious part of Erik’s hospitalization. What is afib, and how is it best treated? And how was Erik’s situation unique? The BRCT on the left depicts the most important aspect of the treatment of afib never discussed with Erik during his stay.
Afib is an irregular heart rhythm in which our heart’s pacemaker sends signals to the atrium (the smaller part of our heart that does very little pumping) so quickly that the atrium quivers rather than pumps. Some of those signals move also to the ventricle (the main body of our heart) causing it to beat very quickly and irregularly. People with afib often notice dizziness, shortness of breath, and palpitations from their rapid heartbeat. Those symptoms can be mitigated by certain medicines to the point that afib can be fully controlled in most cases. The condition itself will not cause other heart problems such as heart attacks.
However, because the atrium quivers and hardly moves, blood clots can develop on the heart wall, and very rarely pieces of those clots can break off and move up to the brain, causing a stroke. The vast majority of people with afib do not get strokes, and even among those who do the strokes are usually small and silent, or they cause symptoms that completely resolve. But for those with large strokes due to afib, the consequences are obviously devastating. The risk of developing a stroke can be reduced by taking some form of “blood thinner,” usually an anti-platelet agent such as Aspirin, or an anti-coagulant such as Warfarin (Coumadin is the brand name). Studies have demonstrated that Warfarin is significantly more effective than Aspirin in preventing strokes among people with afib, cutting the risk by 50% compared to those who take Aspirin. But since disabling stroke (which is a stroke that leave permanent symptoms) is so rare, one has to ask if a 50% reduction is actually significant, and also if there are any untoward consequences of taking Warfarin compared to aspirin.
None of those questions were addressed by the medical team taking care of Erik. When Erik developed afib it was a brief episode that resolved on its own and was without any symptoms. This is not uncommon after heart attacks, and typically it is transient and does not recur. Still, Erik’s team insisted that he take Warfarin immediately to reduce his risk of stroke. He was already on two anti-platelet agents (Plavix and Aspirin) due to his stents, but they believed strongly that Warfarin was necessary for stroke prevention. They cited a 4% chance of his having a stroke unless he took the Warfarin. They did not discuss any downsides of taking the Warfarin, nor did they suggest alternatives. When Erik stated that he was willing to take a 4% risk, the medical team felt that was a very poor decision, and they talked to him several times trying to push him to take the medicine.
What were Erik’s actual risks and benefits of Warfarin? In fact, given his unique situation, the benefits of Warfarin were likely inconsequential, and the risks may have been substantial. That is because Erik’s afib was brief and likely not to return. For clot to develop, and then break off to cause a stroke, a patient needs to be in afib for a reasonable amount of time, usually many months. Certainly a mere few minutes of afib, or even a few days, is not enough time for Warfarin to provide any benefit. It would not have been unreasonable for Erik to wear a monitor after he left the hospital so the doctors could ascertain if he continued to be plagued by afib, in which case Warfarin may provide some benefit in stroke prevention. What would have been the actual benefits and risks for Erik had he continued to be in afib after his hospital stay? Would his risk of stroke be 4% as his medical team suggested?
Multiple studies have suggested that the risk of a disabling stroke is typically lower than the 4% risk cited by Erik’s doctors, and the impact of adding Coumadin confers far less benefit than the often cited 50% risk reduction would suggest. The disabling Stroke rate without any treatment in afib varies with age and other risk factors, from .5% to 2% a year, not all of which is caused by the afib itself. Aspirin can reduce that risk to some extent, as it can with all strokes. How much better does Warfarin work?
As is noted by the BRCT, in one year approximately 6 people out of 1000 in afib will avoid a disabling stroke if they take Warfarin compared to 1000 people who take Aspirin. In other words, 994 people out of 1000 have a similar outcome whether they take Aspirin or Warfarin. Is there any harm to taking Warfarin? In fact, out of 1000 people who take Warfarin compared to 1000 who take Aspirin, approximately 6 will either bleed into their brain causing a hemorrhagic stroke or will die of a bleed, and 40/1000 will have severe bleeding leading to hospitalization. Thus, the life-threatening risks of taking Warfarin are often higher than the benefit of taking Warfarin; while taking it cuts back the risk of ischemic stroke by a small amount, it also increases the risk of having an equally severe hemorrhagic stroke or dying by an equal amount and to bleed by a much larger amount. As with all medical interventions, there is uncertainly in the use of Warfarin, not simple right and wrong answers.
In Erik’s case, the benefits of taking Warfarin were far less than even 6/1000 since his afib was so brief in its duration and the fact that he had virtually no other risk factors. It is very unlikely he would have had any benefit at all. Contrarily his risk of taking Warfarin were quite substantial. That is because the risk of bleeding increases when people combine an anti-platelet agent with Warfarin, and Erik was on two anti-platelet agents (Plavix and Aspirin) because of his stents. Erik’s additional risk of severe bleeding if he added Warfarin to those medicines, according to several studies (Hanson, JAMA IM, 2010; Khurram, J. Invasive Cardiology, 2006) would be 70/1000 in a year, as shown in the BRCT at the top of this blog. In addition, it is also very likely that his risk of having a hemorrhagic stroke and death would have been higher than the 6/1000 for those only on Warfarin. This, while his benefits would be dubious, his risks of taking Warfarin would have been significant and certainly worthy of a discussion by the medical team.
Why, then, did Erik’s medical team push him so hard to take Warfarin despite the hard data that would have suggested he do otherwise, and why were they unwilling to have a discussion with him about the risks and benefits of using the drug? And why did they quote him a 4% risk of having a stroke if he refused to take Warfarin when such a number is both misleading and erroneous? Erik’s contentious relationship with his medical team regarding Warfarin is instructive of several problems that plague medical care today. First, doctors often use inaccurate relative risk/benefit numbers that verge sharply from medical reality. Second, they typically emphasize benefit and minimize or neglect risk. Third, they rarely individualize treatment to patients. And fourth, they do not take the patient’s own preferences into consideration when making decisions. BRCTs can bridge the gap between doctor and patient, enabling a sensible and constructive conversation about medical interventions. Their use would have helped Erik’s medical team manage his afib in a much more helpful way.