ONE of the leading causes of the most disabling and even most fatal of strokes is Atrial Fibrillation (AF), which happens to be the most common type of heart arrhythmia or irregular heartbeat.
In AF, the heart’s turbulent rhythm may cause blood to pool in its upper chambers, or the atria, and form into clots. Blood clots may then dislodge from the heart and shoot into the brain, blocking blood flow, causing a stroke. The worst part? All of it can happen in a snap. There’s a reason why stroke is called the “Silent Killer.”
According to Dr. Gilbert Vilela, one of the country’s leading cardiologist, AF was previously thought of a complicated heart disease, nothing more. He said advancements in the medical field debunked this assumption. In the Philippines, as per data from the Philippine Neurological Association and the Department of Health, AF is the fifth risk factor for stroke among Filipinos.
“AF increases the risk of stroke by five times,” Vilela said in a recent media briefing in Makati City. “Without preventive treatment, approximately 1 in 20 patients with AF will have a stroke.”
Vilela added that at risk for AF are patients with enlarged heart, hypertension or diabetes, as well as those over 65 years old. With Asia’s rapidly aging population, the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation, or GARFIELD-AF, estimated that by 2050, the continent will have 72 million cases of AF, with 2.9 million among them suffering from an AF-associated stroke.
The obvious solution to blood clotting is, of course, blood thining. For decades, Warfarin was the only drug used to deliver this effect, called anticoagulation, or the reversal of the process wherein blood changes from a liquid state to a solid or semi-solid state.
But just because it was the lone anticoagulant treatment for AF didn’t mean it was perfect.
Warfarin is a drug with numerous interactions. Patients who take it as a maintenance med have to watch their diet to an almost obsessive degree.
For one, conventional knowledge teaches us to eat our greens when sick, but this doesn’t apply to patients with AF. Green, leafy vegetables are rich in Vitamin K, which plays a key role in helping the blood clot. The drug also interacts with other drugs, such as mefenamic acid, which can worsen the bleeding of a patient.
Meanwhile, Vilela cited a former patient on Warfarin who had his molars extracted. The patient didn’t disclose his intake of the drug and went on with the surgery. Since he was on blood thinners, he bled profusely and was rushed to the ICU. Vilela said the patient survived, but his pocket barely did.
This is just an extreme case of Warfarin’s financial impact, but there are other manifestations, too. The drug itself is affordable. However, its dosage is notoriously difficult to get right, which leads patients to frequent visits to the doctor for recalibration. Too small of a dose renders the drug ineffective. Too much can lead to internal bleeding.
The fear of bleeding internally is also the reason that has kept most Filipinos and Asians in general at bay with the use of Warfarin, and, by extent, treatment to AF. As compared to other races, Asians were thought of as heavy bleeders, based mostly on diet and genetics.
To shed light on this assumption, a recent “real-world” study on the prevention of stroke in Asian AF patients was done on new anticoagulants simply called Novel Anti-Coagulants (NOACs).
The study, titled XANAP, followed 2,273 Asian patients from 435 sites across Asian sites, including the Philippines, in routine clinical practice.
Observed were elderly patients with a mean age of 70.5 years old, who had varying levels of stroke risk, with significant medical co-morbidities including heart failure, hypertension and diabetes mellitus, among others.
The study yielded positive results of a low bleeding rate of 1.5 percent per year and low stroke rate of 1.7 percent per year in AF patients treated with non-vitamin K antagonist oral NOAC Rivaroxaban, a drug marketed under the brand name Xarelto, from German multinational pharmaceutical and life science company Bayer. Over 96 percent of patients treated with the drug did not experience any major bleeding, stroke/systemic embolism, or all-cause death.
This means NOACs like Rivaroxaban match Vitamin K Antagonists (VKA) like Warfarin in stroke prevention, but with easier administration and significant reduction of risk from life-threatening bleeding. Other benefits include predictable anticoagulation, eliminating frequent trips to the doctor, thus saving patient’s money; reduced potential for food and drug interactions, as well as simplified and fixed dosage. It is taken once a day, just like a vitamin supplement. (Before initiating therapy with anticoagulant medicines, physicians should carefully assess the benefit and risk for the individual patient.)
Moreover, the world has already taken notice of NOAC’s benefits, according to GARFIELD-AF. Between 2010 and 2015, patients receiving anticoagulant treatment for stroke prevention have increased from 57 percent to 71 percent. Conversely, the same period recorded a fall in use of VKA and antiplatelet (combined or not) from 83.4 percent to 50.6 percent.
However, the study revealed that in Asia, almost 20 percent of AF patients receive no therapy. Meanwhile, more than 60 percent still receive either VKA (with or without antiplatelet therapy) or antiplatelet therapy only. The figures show that the benefit of NOACs over VKA is still not fully understood by the general public, but the findings of XANAP look to change that.
According to Professor Young-hoon Kim of Korea University Medical Center, XANAP principal investigator, while NOACs offer a new standard of care in preventing AF-related strokes, major bleeding is a key consideration of doctors when prescribing NOACs for AF patients. But with the XANAP’s findings, they can operate with more clarity.
“This data confirms the low bleeding risk of Rivaroxaban in Asian patients, thus reaffirming its positive benefit/risk profile, and demonstrate its value in preventing the negative impact of stroke on patients and society,” Kim said in a statement.
Echoing the sentiment is another XANAP principal investigator, Professor Chia-Ti Tsai of National Taiwan University Hospital. He said that while it is important to consider a patient’s individual risk factors to prescribe the right NOAC for AF stroke prevention, Rivaroxaban’s robust experience and evidence in patients across different risk profiles, including those with high stroke risk, will best support doctors and patients in their treatment decision in AF management.