ARTICLE IN BRIEF
A new study found that patients and their caregivers could be successfully taught to distinguish between normal or arrhythmic pulse indicating possible paroxysmal atrial fibrillation.
With proper training, acute ischemic stroke (AIS) patients and/or their caregivers can learn to distinguish paroxysmal atrial fibrillation from normal heart rhythm by taking a simple wrist pulse measurement, according to a study published in the July 23 online edition of Neurology.
Measured peripheral pulse (MPP) is the only technique recommended by international guidelines to detect paroxysmal atrial fibrillation (pAF), but many false alarms could be prevented if it is done at home, according to Bernd Kallmünzer, MD, and colleagues at the Universitätsklinikum Erlangen, in Erlangen, Germany.
The researchers tested the accuracy of home-monitored MPP in a prospective study involving 256 patients trained to take their wrist pulse and detect pAF using a stopwatch. The study included all AIS patients treated at a single tertiary care facility between April 2012 and February 2013. They compared data on simultaneous blinded electrocardiogram (ECG) for diagnostic accuracy and reviewed outcomes.
Patients and caregivers were taught how to distinguish between normal or arrhythmic pulse indicating possible pAF. If two subsequent measurements were accurate after training, it was considered a success. Patients with known pAF were included only if they were unaware of their current heart rhythm at the outset and during MPP.
Prior studies have shown that pulse taking by health care professionals had repeatedly high sensitivity for AF detection, ranging from 92 percent 100 percent.
In this study, the accuracy in taking MPP by health care professionals or patient's relatives had a diagnostic sensitivity of 96.5 percent and 76.5 percent, respectively, they found, with 94.0 percent and 92.9 percent specificity in detecting AF. Among competent patients, 89.1 percent reliably performed self-measurements, with a diagnostic sensitivity of 54.1 percent and 96.2 percent specificity. Further, the rate of false positives was low — at only 2.7 percent of cases — with a positive predictive value of 76.9 percent and a negative predictive value of 90 percent.
“Survivors of ischemic stroke are at high risk for paroxysmal atrial fibrillation, although the episodes are often asymptomatic,” Dr. Kallmünzer told Neurology Today. “Although the episodes are often asymptomatic, the patients with AF should be offered antithrombotic treatment to prevent cardioembolism and recurrent stroke.”
The prevalence of AF is 5-20-fold higher among ischemic stroke survivors than in the general population, the study authors noted.
“Taking peripheral pulse is easy, free, and non-invasive, but highly effective as a first-step screening tool,” said Dr. Kallmünzer. “Many patients can be educated to distinguish between normal and absolute arrhythmic pulse sensation although they suffer from neurologic deficits from their stroke, and for patients with more severe handicaps, family members may perform the pulse measurements with a remarkable high sensitivity and specificity. Therefore, as a first-step in detecting atrial fibrillation, MPP offers a powerful tool in identifying patients needing additional cardiologic care and thorough ECG monitoring.”
The study authors noted that every case of pathologic MPP requires an ECG to confirm or refuse the diagnosis of AF.
AIS patients are susceptible to a wide range of different cardiac arrhythmias in addition to AF, many of which are associated with irregularities of the peripheral pulse, but MPP may be beneficial in identifying these as well. The study did not investigate its performance in arrhythmias other than atrial fibrillation.
“Notably, there were no cases of atrial flutter in this study, which may be missed by MPP in case of rhythmic atrioventricular conduction depending on the resulting pulse rate,” according to the researchers. Moreover, a history of Afib or oral anticoagulation, and the subtype of Afib (paroxysmal vs. persistent/permanent) could bias the accuracy of MPP by patients and relatives, even though a subgroup analysis of patients with detected and undetected AF episodes did not show this to be the case, they wrote.
LARGER STUDY UNDERWAY
MPP has been included in guidelines by the European Society of Cardiology in the highest class of recommendations and with the second-highest level of evidence.
Inclusion in the guidelines is largely based on data from a multicenter clinical trial involving 14,802 patients in the United Kingdom, where selective ECGs guided by preceding MPP has been shown to be equally effective for AF detection compared with primary repeated ECG.
“Given these promising results and the high prevalence of pAF among patients with stroke of unknown cause, we suggest that MPP-guided ECG diagnostics should be considered for all secondary stroke prevention programs,” Dr. Kallmünzer said.
Because the study was conducted at a single tertiary care unit, and in a relatively small number of subjects, other studies are needed to confirm the findings, he noted. The team has initiated a prospective clinical trial with MPP guided ECG diagnostics, which is already recruiting.
‘VALUABLE FIRST STEP’
In a 2008 study published in Neurology, a team of researchers reported that continuous cardiac telemetry monitoring can accurately detect pAF in patients with cryptogenic stroke. The findings were confirmed in a 2012 study.
Lead author Ashis Tayal, MD, medical director of the Comprehensive Stroke Center at Allegheny General Hospital and a neurologist with Western Pennsylvania Allegheny Health System in Pittsburgh, told Neurology Today that this new study represents “a valuable first step” in advancing self- and mobile-monitoring devices.
“This is an exciting study because it adds another piece of the puzzle in pAF after stroke,” he commented.
“Many pAF episodes are silent and are often very short, so I am very encouraged by this paper. It provides an elegant, simple technique that can reliably detect pAF. A number of studies since our 2008 paper have been conducted, but the technology has yet to catch up.”
Today, 24-hour Holter monitoring for two to four weeks, or implantable loop recorders, are the most common options for patients with arrhythmias, but both have a number of challenges, including cost and appropriate application, he noted.
Dr. Tayal said that one day it might be possible for a patient to wear a wristwatch-like monitor that could detect episodes of pAF on an ongoing basis, providing data on rhythm changes that would be very valuable in helping better guide treatment decisions, he added. “But until then, having them able to monitor themselves, or with assistance from a family member, is a good start.”
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