Many patients (and perhaps physicians) are confused as to how best to utilize personal ECG devices. I received this question illustrating such confusion from a reader recently:
"I first came across your website a year ago during persistent angina attacks, and returning now due to increasing episodes of symptoms akin to Afib [atrial fibrillation]. I bought a Kardia 2 yrs ago for the angina episodes, and looking to buy the Apple Series 4 for the Afib, as I want to try a wearable for more constant monitoring. What I would greatly appreciate is if you had a basic guide for both the Kardia & Apple devices, specifically when and how to best employ them for unstable angina and detecting undiagnosed Afib. As in, what can I as a patient provide to you as a doctor for diagnosis in advance of a formal visit. I'm a U.S. Iraq vet medically retired in the U.K., and most of my concerns get dismissed out of hand as 'anxiety,' not sure why they thought a stent would cure my anxiety though."
First, please understand that none of these devices have any significant role in the management of angina. Angina, which is chest, arm, and jaw discomfort due to a poor blood supply to the heart muscle cannot be reliably diagnosed by the single-lead ECG recording provided by the , the or the .
Even a medical-grade 12 lead ECG doesn't reliably diagnose angina. We rely on a constellation of factors, from the patient's history to advanced testing, to determine how best to manage and diagnose angina.
Second, as you are having episodes "akin to Afib," all of these devices can be helpful in determining what your cardiac rhythm is at the time of the episodes, if they last long enough for you to make an ECG recording.
The single-lead ECG recording you can make from the Apple Watch, the KardiaBand, and from the Kardia mobile device can very reliably tell us what the cardiac rhythm was when you were feeling symptoms.
The algorithms of these devices do a good job of determining if the rhythm is atrial fibrillation. Also, if the rhythm is totally normal, they are good at determining normality.
However, sometimes resulting in an unclassified tracing and (rarely) an inaccurate declaration of Afib. These tracings can be reviewed by a competent cardiologist to sort out what the rhythm really is.
In all of these cases, having an actual recording of the cardiac rhythm at the time of symptoms is immensely helpful to your doctor or cardiologist in determining what is causing your problems.
My recommendation, therefore, would be to make several recordings at the time of your symptoms. Print them out and carefully label the print-out with exactly what you were feeling when it was recorded, then present these to the doctor who will be reviewing your case.
As I've mentioned in previous posts (see ), my patients' use of Kardia with the KardiaPro online service has, in many cases, taken the place of expensive and inconvenient long-term monitoring devices.
Case Example
I recently saw a patient who I think perfectly demonstrates how useful these devices can be for clarifying what is causing intermittent episodes of palpitations.
She was lying on a sofa one day when she suddenly noted her heart "pumping fast" and with irregularity. The symptoms last for about an hour. She had noticed this occurred out of the blue about once a year.
Her PCP ordered a long term monitor, a stress test, and an echocardiogram.
The monitor showed some brief episodes of what I would term atrial tachycardia, not atrial fibrillation, but the patient did not experience one of her once-per-year, hour-long episodes of racing heart during the recording. Thus, we had not yet solved the mystery of the prolonged bouts of racing heart.
She was referred to me for evaluation. I recommended she purchase an AliveCor device and sign up for the which allows me to view all of her recordings online. The combination of the device plus 1 year of the KardiaPro service costs $120.
She purchased the device and made some occasional recordings when she felt fine, and we documented that these were identified as normal by Kardia. For months, nothing else happened.
Then one day in April, she had her typical prolonged symptom of a racing heart and she made the recording below. (She was actually away from home but had the Kardia device with her.)
When she called the office, I logged into my KardiaPro account and pulled up her recordings. Lo and behold, the Kardia device was correct and she was in atrial fibrillation at a rate of 113 BPM.
With the puzzle of her palpitations solved, we could now address proper treatment.
Continuous Monitoring for Abnormal Rhythms
Finally, let's discuss the wearables' ability to serve as a monitor and alert patients when they are in an abnormal rhythm but free of any symptoms.
My reader's intent was to acquire an Apple Series 4 device for "constant monitoring."
This capability is theoretically available with Apple Watch 4's ECG and with the KardiaBand (), which works with Apple Watch Series 1-3.
However, I have not been impressed with Apple Watch's accuracy in this area (see and ) and would not, at this point, rely solely on any device to reliably alert patients to silent or asymptomatic atrial fibrillation.
In theory, all wearables that track heart rate and alert the wearer if the resting heart rates goes above 100 BPM have the capability of detecting atrial fibrillation. If you receive an alert of high heart rate from a wearable without ECG, you can then record an ECG with the Kardia mobile ECG to see if it really is atrial fibrillation.
At $99, the Kardia is the most cost-effective way of confirming atrial fibrillation for consumers.
I hope this post adds some clarity to the often confusing field of personal and wearable ECG devices.
, is a private practice noninvasive cardiologist and medical director of echocardiography at St. Luke's Hospital in St. Louis. He blogs on nutrition, cardiac testing, quackery, and other things worthy of skepticism at , where a version of this post first appeared.