The effective therapeutic window for warfarin is very narrow and its risk of bleeding is definitely present, but the risk of thromboembolism from atrial fibrillation is greater without the use of anticoagulants. Therefore, it is worthwhile to risk some bleeding to gain the benefit of preventing thromboembolism, and the overall benefits outweigh the disadvantages. Warfarin should always be monitored during administration. INR stands for International Normalized Ratio, which reflects the anticoagulant effect of warfarin. Generally speaking, INR values within the range of 2.0-3.0 have the best anticoagulant effect, which means that the risk of thromboembolism is minimized and the risk of cerebral hemorrhage is also minimized. It is evident that maintaining a balance of risk and benefit is critical.
Frequency of INR monitoring
Warfarin is currently available in two doses of 2.5 mg and 3.0 mg, with most patients receiving 3.0 mg. Initially, the INR needs to be monitored by weekly blood draws, which can be reduced to once a month as the INR stabilizes. After one or two years of stabilization, monitoring can be done once every 2-3 months.
Treatment when INR value fluctuates
1. When the drug is first started, the dose adjustment of warfarin should be based not only on the measured value of INR, but also on the trend of INR changes. Generally, on the 5th day after the application of warfarin, if the INR has a rising trend, but has not yet reached the lower limit of the treatment target, it should be noted that the dose needs to be reduced if necessary. It should be noted that the INR will change only a few days after warfarin dose adjustment, so dose adjustment should not be too frequent.
2, in general, if the INR value is only a little higher, such as 3.2, 3.3, do not need to stop the drug, after a few days to draw blood to strengthen the monitoring can be; if the decrease a little, such as 1.7, 1.8, also do not need to increase the drug, again, after a few days to draw blood to monitor. If this happens repeatedly, we should consider whether we need to adjust the medication. For example, if the INR of a patient taking warfarin for a long time is measured several times and the results are stable outside the target range, and the target target is 2.0-3.0, for example, and the results of three consecutive INR measurements are 2.0, 1.8, and 1.8, you can consider increasing the warfarin dose appropriately. However, when there is a large difference between consecutive measurements, such as 2.0, 3.0, 1.8, it is best to maintain the original dose. patients with large fluctuations in INR are most likely to have thromboembolic or bleeding complications, and these patients should be reminded to maintain a stable intake of vitamin K in their diet, to take the medication as prescribed, and to monitor INR regularly.
3. However, if the INR value fluctuates widely, for example, if it appears to be 5.0 or even 10.0, it may be necessary to discontinue the medication while looking for reasons, such as whether antibiotics are being taken or if it has not been monitored for a long time.
Finding signs of bleeding
For minor bleeding, such as bleeding gums when brushing teeth, bleeding spots after skin bump, etc., it can be ignored and usually has little effect. For serious bleeding, such as bleeding in the urine or stool, it is important to pay attention to it. Dark stool, like the color of pig’s blood or duck’s blood after eating it, but in fact not eating pig’s blood or duck’s blood-type food, may indicate the presence of digestive tract bleeding in the body. If the urine appears soy sauce colored (normal urine is light yellow or white), it also indicates that there may be bleeding in the body.
A more serious case is brain hemorrhage. When there is a sudden headache, nausea, vomiting, dizziness, etc., or when there is a particularly abnormal condition, there is a high probability that a serious brain hemorrhage, spinal cord hemorrhage, or fundus hemorrhage has occurred. Therefore, patients should be informed that they need to seek immediate medical attention in the event of these conditions.
Be aware of the effects of other drugs on the effects of warfarin
Many medications have an effect on the effects of warfarin, the most common of which are antibiotics. If the medication the patient is taking changes, such as taking antibiotics for several days in a row, it is important to consider whether the medication needs to be adjusted or if monitoring should be increased. However, if the medication taken remains the same year-round, there is no need to worry much about it.
Remedies for missed warfarin doses
If you miss a dose of warfarin on one day, you can add half a tablet the next day; then return to normal on the third day. In addition, there are always inquiries from patients about the time of day when warfarin should be taken once a day, because warfarin is metabolized very slowly, so its effect is not related to the specific time of day it is taken.
Expert tips: need to correct the medication chaos in patients with atrial fibrillation
1, some time ago, to give a lecture to primary care doctors, for atrial fibrillation drug treatment, I told them three words: forget aspirin; forget amiodarone; remember warfarin.
2. Although not absolute, this should be true for most patients. Medication, the most important thing is these three, the rest are not important.
3, among our patients with atrial fibrillation, nearly 70% apply aspirin, which is a common mistake. In fact, aspirin, however, has no real significance in preventing stroke in atrial fibrillation. At present, international studies generally agree that aspirin is ineffective in treating thromboembolism caused by atrial fibrillation, and aspirin for atrial fibrillation has been largely discredited. However, aspirin is effective for thromboembolism caused by coronary heart disease and can reduce the occurrence of myocardial infarction. If a patient has both coronary artery disease and atrial fibrillation, they may need to take warfarin and aspirin at the same time.
4. Amiodarone is the most used and overused, but the least important and least needed. Of the thousands of patients we see in our clinics each year, the most patients use amiodarone, but 80% of them should not. For patients with infrequent episodes of atrial fibrillation, who have several episodes a year, there is no need to take a drug whose side effects far outweigh the benefits; and for patients with very frequent episodes, why should they take long-term medication when catheter ablation therapy is more appropriate.
5. In addition to amiodarone, the most common antiarrhythmic drugs are cardioplegia. Cardioplegia also has side effects and is not as effective as amiodarone, so long-term application of cardioplegia is not very helpful for patients with atrial fibrillation.