I’ve been using AliveCor’s Kardia personal ECG devices to help manage my patients with atrial fibrillation (AF) for 7 years now. Early on, I pointed out (see here) that Kardia was easily confused by extra beats, both premature atrial contractions (PACs) and premature ventricular contractions (PVCs).
Such rhythms were sometimes diagnosed incorrectly as atrial fibrillation but more commonly were designated “unclassified.” For patients, especially those not connected like mine are to a cardiologist through KardiaPro, the inconclusive readings were often a source of consternation. This problem was not solved by the six-lead Kardia.
Kardia is not alone in being confused by PVCs and PACs. Apple Watch has the same problem. Even highly-sophisticated, computerized interpretations of 12-lead ECGs often confuse premature beats with atrial fibrillation. Such misdiagnoses trigger cardiology consults routinely. Even board-certified cardiologists, especially if they are reading rapidly and carelessly, not infrequently misread sinus rhythm with PACs as atrial fibrillation.
It was exciting, therefore, to read AliveCor’s announcement that the company has been given 510(K) clearance by the FDA for use of new interpretive ECG algorithms (AI V2) that are designed to recognize and diagnose these premature beats.
I recently had the opportunity to discuss AI V2 with David Albert, MD, founder and chief medical officer of AliveCor.
The focus of the improved algorithm, Albert said, was to reduce the number of unclassified Kardia recordings and help patients deal with irregular heart rhythms or palpitations that are not atrial fibrillation.
The AI algorithm has been improved by analysis of 90 million ECGs AliveCor has access to, so Kardia’s accuracy at detecting atrial fibrillation will be substantially better with AI V2, Albert indicated.
AliveCor’s internal studies indicate that this combination of accurate identification of PVCs and PACs plus improved AF recognition will lower the number of unclassified Kardia ECGs by 80%.
Albert indicated the accuracy of AI V2 recognizing PVCs and PACs as determined by internal testing of thousands of ECGS is high with both sensitivity and specificity >90%.
Lead I Versus Lead II
Both the original Kardia single-lead device and the newer six-lead KardiaMobile utilize Lead I (left arm-right arm electrodes) information to identify cardiac rhythm, so users can anticipate a diagnostic improvement in both versions when the new software is released in early 2021. Albert indicated that several external researchers are eager to test AI V2 in real-world patients at that time.
Of course, KardiaMobile 6L has lead II (left arm-left leg electrodes) available for rhythm analysis, and Albert indicated that AliveCor will “very soon” receive approval for utilization of lead II analysis for rhythm determination. Lead II is often superior to lead I for detecting p waves, the hallmark of normal sinus rhythm.
Atrial flutter, because it is often very regular, is often misdiagnosed by computerized algorithms that are utilizing only lead I, whereas it is typically easy to spot in lead II.
Albert anticipates that KardiaMobile 6L utilizing lead II analysis will receive approval for diagnosing atrial flutter and will be proven even more superior for diagnosing PVCs, PACs, and AF.
I am eager to see the accuracy and utility of AI V2 in my Kardia-carrying patients and will update readers when I have my own evaluation of the new algorithms.
I’ll talk more about AliveCor’s recently-announced KardiaCare program and about lead II recordings with Apple Watch in future posts here.
Anthony C. Pearson, MD, is a noninvasive cardiologist and professor of medicine at St. Louis University School of Medicine. He blogs on nutrition, cardiac testing, quackery, and other things worthy of skepticism at The Skeptical Cardiologist, where a version of this post first appeared.