Personal ECG devices like Apple Watch and KardiaMobile are wonderful for most people at recording a single-lead ECG and determining cardiac rhythm. With both devices, however, it is not uncommon to get an inconclusive (Apple’s term) or unclassified (AliveCor’s term) reading at times.
I’ve discussed some fixes for KardiaMobile here. Often recordings can be drastically improved by moistening the skin contacting the two electrodes, thereby improving the conductance of the electrical signal. Minimizing movement helps many cases. But for some, this is the norm no matter how elaborately fingers are lubricated or how aggressively motion is eliminated.
A reader emailed me with his very frustrating case which typifies this problem:
“Not sure if you can help me but I wanted to reach out based on a post I saw from you online. I have advanced CAD (CT scan calcium score of 2,300) and purchased an Apple Watch 5 about a year ago to be able to monitor my heart rate and do ECGs. I am unable to get a consistent Sinus Rhythm even though I know I have a normal ECG.
“In fact the display when I am taking an ECG is all over the map – many times it looks like a three-year-old coloring with a crayon. I have worked with Apple support, they sent a new watch but the same issues. I then was asked to submit my data file to engineering after I replicated the issue, and that was done in February. Now when I call support they basically tell me ‘don’t call us we will call you’ and the standard answer is ‘engineering is still looking into it.’
“I am convinced there is something with me physiologically that prevents the watch from doing consistent ECGs with me. I believe Apple engineering knows there is a deficiency and no solution so just ignoring it. I am not sure what recourse I have other than to try and find others with similar issues and go down a class action lawsuit rat hole. I was curious though if you had come across this issue in the past and/or you know of groups that might be organizing to pursue some type of action from Apple.”
I asked him to send me examples of his inconclusive Apple Watch (AW) ECGs, and it was clear that this individual (we’ll call him Don) suffered from what I term “Low Lead I Voltage Syndrome.”
Here’s a typical recording for him. Note that the squiggles that correspond to electrical activation of the ventricles (the QRS complexes) can be barely be discriminated from the background noise of the tracing. Understandably, the AW algorithm can make neither heads nor tales of such a scribble. Even the Skeptical Cardiologist, who prides himself on interpret