At its annual September event last week, Apple announced the Apple Watch Series 4, which will run separate electrocardiography (ECG) and irregular heart rhythm apps. The ECG app will be “capable of generating an ECG similar to a single-lead electrocardiogram” within 30 seconds, after a user places their finger on the smartwatch’s digital crown, which has electrodes built in. The irregular heart rhythm app will be able to detect most cases of arrhythmia, or irregular, too fast or too slow, heart rhythms, Apple said. A crystal electrode at the back of the watch will read the heart’s electrical impulses from the wearer’s wrist.
Apple said it had “FDA clearance” for these features. Does that mean we now have a wearable ECG device that will do away with the need to visit a hospital or other diagnostic centre for an electrocardiogram?
What does FDA clearance mean?
The Food and Drug Administration is the US federal public health regulator. FDA clearance, which the Series 4 has got, is not the same as FDA approval. The USFDA classifies some 1,700 generic types of medical devices, each of which is assigned to one of three regulatory classes based on the level of control necessary to assure the safety and effectiveness of the device. The Series 4 is a Class II device (which means it must have special labelling and meet mandatory performance standards, and the company shall conduct post market surveillance); Class III devices are the most complicated devices, and need compulsory pre-market approval as well.
The FDA clearance notes that the ECG feature is not meant for those under 22 years of age and for anyone with known arrhythmia or other heart-related problem. The app is “electrocardiograph software for over-the-counter use” that can “analyse” and “display electrocardiograph data” and “provide information for identifying cardiac arrhythmias”. The data displayed by the app “is intended for informational use only”, and “is not intended to provide a diagnosis”, the FDA says. Users must not “interpret or take clinical action based on the device output without consultation of a qualified healthcare professional”.
The “software-only” medical application can “create, record, store, transfer and display” a single channel ECG, which, according to the FDA, will be similar to a 1-lead ECG. A 1-lead ECG records the electrical activity of only the lateral wall of the left ventricle, which is the thickest of the heart’s four chambers, and pumps oxygenated blood to all tissues of the body.
The FDA clearance on the irregular heart rhythms app, too, says it should not be used by those under age 22, or those with a known history of irregular heart rhythms. “It is not intended to provide a notification on every episode of irregular rhythm suggestive of AFib (atrial fibrillation or arrhythmia) and the absence of a notification is not intended to indicate no disease process is present; rather the feature is intended to opportunistically surface a notification of possible AFib when sufficient data are available for analysis,” the FDA clearance says.
Essentially, then, while the watch can detect unusually low or high heart rates or irregular heart rhythms and warn a wearer, it may not detect all issues. And it cannot replace traditional methods of diagnosis by a doctor.
Is this the first time the USFDA has given such clearance?
No. A Mountain View, California-based medical device and artificial intelligence company called AliveCor received FDA clearance last year for a similar electrocardiograph software for OTC use. Its KardiaMobile app works with most smartphones and tablets (both Android and iOS) and, according to the company, “captures a medical-grade EKG in 30 seconds anywhere, anytime”. A more premium KardiaBand is available, which “replaces (the) original Apple Watch band providing access to an EKG anytime, anywhere”. The machine learning algorithms running on the device reports result like ‘Normal’, ‘Possible Atrial Fibrillation’, ‘Unclassified’, and ‘Unreadable’.
Apple submitted to FDA the results of the Apple Heart Study done in partnership with Stanford Medicine, which found the software could accurately identify AFib in over 98% of patients. The study included 588 individuals, half of whom had AFib, the rest had healthy heart rates.
How does an ECG device work, and how is it different from the ECG app?
In cardiology, ECG is treated as the gold standard for diagnosis of cardiac arrhythmias and other abnormalities. The heart is a 2-stage electrical pump, and an ECG assesses its muscular and electrical functions — the rate and rhythm of the heartbeat, and indirect evidence of blood flow to the heart’s muscles. A conventional ECG device has 12 leads, and 10 electrodes are placed on the patient’s limbs and chest. The electrodes, which are typically wet sensors that use a gel to increase conductivity with the skin, pick up electrical activity and produce 12 electrical views of the heart. It is a very simple test; however, only a trained specialist can interpret an electrocardiogram.
Arrhythmia only means irregular heartbeats that can both indicate a medical emergency, or be harmless. They can occur for broadly five reasons: heart disease, healing process after heart surgery, injury from a heart attack, changes in heart muscles, and an imbalance of electrolytes — sodium or potassium — in the blood.
Arrhythmias can be of several types. The Apple ECG app can only determine AFib, a common irregular rhythm that occurs due to poor blood flow, and causes the upper chambers of the heart to contract abnormally. While there may be no symptoms in some cases, most commonly patients experience shortness of breath, fatigue and palpitations. It can result in blood clots, stroke, heart failure and other complications.
Other types of arrhythmias include premature atrial contractions or “extra beats” that originate in the upper chambers and are considered harmless; “skipped heartbeats”, or premature ventricular contractions that are usually caused by excessive intake of caffeine or nicotine, stress, electrolyte imbalance, or heart disease; and atrial flutter that occurs in the first week after heart surgery. Only a specialist can determine the reasons and treatment for such arrhythmias.
So does this mean that the new health apps in the Apple Watch Series 4 are going to be of no help?
While it might appear that Apple is overselling somewhat its ECG and irregular heart rhythm features, these are, indeed, extremely helpful apps in today’s stressed out times. Data from the Apple Watch can help alert a wearer to a possible cause for alarm. Smartwatch wearers, including wearers of earlier series Apple watches have reported being alerted to possible heart attacks by the heart rate sensor in their devices, with the danger having been confirmed subsequently by emergency room tests. Clearly, there are advantages to the new health monitoring apps — and Apple has itself underlined that they are not meant to replace the doctor.