By: Satish Misra MD and Iltifat Husain MD
In our video review, we take a close look at the AliveCor heart monitor’s features and real life functionality. In the text portion of this review, we explain what the device can and cannot do — and attempt to bring clarity to this mobile heart monitor’s capabilities. For example, we touch on how the device does not replace a 12 lead ECG and will miss heart attacks — an impression the general media appears to think is not the case and something the device makers never touted the device can do in the first place. Overall, we walked away impressed with the elegance and simplicity of the device.
We did, however, find ourselves feeling that while anyone, including patients, should be able to readily use this device to capture reasonable single-lead tracings, we did not have a good sense of when (or whether) they should. Also, in defense of his product, Dr. Dave Albert (inventor) has referenced multiple times that AliveCor had 100% sensitivity and 96% specificity in identifying atrial fibrillation — however, published medical literature has shown a simple iPhone 4s camera app without the need of external hardware has a sensitivity of 96% and specificity of 98%, and costs significantly less than the AliveCor heart monitor ($199.99). Something we discuss further in our conclusion.
Potential Use Cases
Event Monitor, but does the literature support its use?
A potential use of the AliveCor heart monitor is as a non-continuous, patient-triggered event monitor. It’s not hard to imagine a patient walking into clinic for palpitations and walking out with one of these devices. The form factor of the device could help drive patient adoption.
This does not mean every patient should get one of these devices. As noted in a 2010 review of ambulatory arrhythmia monitoring in Circulation, these types of event monitors (which have been around for some time) have limitations. For example, they will not catch the initiation of an arrhythmia, which has diagnostic value. They will also miss short arrhythmias.
It’s also important to consider whether a dizzy, lightheaded patient — often the side effect of having active arrhythmias — will actually be able to successfully operate the device, as some studies have found that 25% of patients with continuous event monitors fail to trigger and transmit tracings when they are symptomatic despite nearly all of them being able to do it in a test environment. Patients who were more familiar with technology, at least to the level of using an ATM, were more likely to be successful [1,2].
Finally, as wearable sensors make big strides in miniaturization and connectivity, We wonder whether this device will be able to hold its own, at least for this indication.
The portability, connectivity, and price point of the device all make it seem like a natural fit for settings where access to more advanced equipment like an EKG machine would be difficult. Scenarios range from third world countries to community outreach and home visits.
Use of screening in these situations is one we have heard proposed in other forums and it was the subject of an abstract presented at the 2012 AHA Conference. In terms of what the device would enable screening for, the first thing that comes to mind is rhythm abnormalities like conduction blocks, QT prolongation, atrial fibrillation, and so on. For most of these conduction abnormalities, there are not recommendations to routinely screen healthy individuals. We do not think it would offer much information in regards to screening for prior ischemic heart disease or chamber abnormalities — especially since the device is only a single lead tracing of an ECG.
For patients who have recently had an EP procedure done and do not already have an implanted cardiac device, it could be used for periodic post-procedure follow-up. Imagine a patient who has undergone an atrial fibrillation or atrial flutter ablation; on discharge, they could be given this device and asked to obtain, say, three 2-minute tracings daily plus with symptoms.
There is some evidence that detecting early post-ablation recurrence of atrial fibrillation would have clinical significance, perhaps pushing for an earlier repeat ablation. In these cases, we do not think a non-continuous event monitor such as AliveCor would be sufficient, as silent atrial fibrillation is quite common, and the intermittent nature of AliveCor would not be ideal for this pathology.
Silent Atrial Fibrillation
There has been some debate about silent atrial fibrillation and CVA risk, with some recent studies identifying higher rates of silent atrial fibrillation in cryptogenic CVA patients when applying 30-day continuous monitoring as opposed to 24-48 hour monitoring. However, as far as large population screenings go, large trials have found no difference between simply palpating a pulse and getting an ECG in episodic screening interactions; in fact, palpation with follow-up ECG if needed is the recommendation of the European Society of Cardiology.
Perhaps one could make a case that the follow-up ECG could be replaced by a lower cost single lead tracing by AliveCor and potentially save an individual a trip to the clinic (and associated costs). However, with a new diagnosis of atrial fibrillation, we would think at least a history and physical exam would be warranted to evaluate for contributing etiologies (e.g. pulmonary disease, cardiomyopathy, etc) and a 12-lead ECG, not a single lead (AliveCor) in this case.
One important point is this device has significant limitations in the acute evaluation of chest pain associated with heart attacks. A single lead I tracing will miss many real ischemic events, enough that even if it was stone cold normal it would not change our suspicion of myocardial ischemia. If there are significant elevations or depressions, it would probably raise our suspicion for myocardial ischemia, but we would still need a 12 lead ECG, begging the question of how it changes management. This doesn’t even touch on NSTEMI patients who do not necessarily show acute or dynamic ECG findings when having a heart attack and associated chest pain. The lay public is often unaware a heart attack can be present without acute ischemic changes on ECG findings.
The issue of false positives
One additional issue worth considering is that of false positives. If this device does in fact expand screening for cardiac disease, there will certainly be an increased rate of false positives and it’s important to consider the consequences for those individuals. Perhaps it will be as simple as a follow-up 12 lead ECG. Or perhaps it will be detection of ST-segment deviations in asymptomatic individuals that will lead to trips to the local ER. In making determinations about the best application of this device, it will be important to consider and quantify these risks so we can ensure the benefits outweigh the risks.
Excessive screening and potential harm
The United States Preventive Services Task Force as recently as last year reinforced their screening ECG criteria, giving a Grade D recommendation for ECG screening in asymptomatic low risk individuals. Grade D meaning they recommend against this type of medical practice. They went on to say there is evidence that suggests screening asymptomatic, low risk adults could result in harms, such as unnecessary invasive testing and procedures, over treatment, and labeling. Even the American Heart Association and American College of Cardiology’s guidelines suggest risk factors such as diabetes and hypertension necessary for screening ECGs.
All in all, the AliveCor Heart Monitor is wonderfully designed and easy to use; these are key strengths for adoption in healthcare. That is — if appropriate uses can be identified.
Before we would prescribe this device to a patient, there are many questions we would want answered first.
- How well does it function with real-world, symptomatic patients?
- Does the form factor overcome the limitations of an intermittent event monitor?
- If its proposed use is screening, is it really better than current techniques (e.g. palpating a pulse for atrial fibrillation)? Or even using a cheaper camera app to do this?
- Does the device allow me to find pathology that leads to an intervention that helps my patient without exposing them to unnecessary tests/procedures due to false positives?
This is our analysis on a device that, in some ways, has become the poster-child for mHealth devices. That status can largely be attributed to the elegant design, ease of use, and low cost that make it far less intrusive and far more portable than traditional medical tools.
However, when it comes to clinical use, question remain. Other disruptive technologies, such as camera apps for arrhythmia detection or wearable sensors may provide more clinically relevant data at lower costs. Furthermore, there are important outstanding questions regarding appropriate utilization of the AliveCor Heart Monitor to ensure we are in fact benefiting our patients and not harming them or wasting their resources with unnecessary testing — we encourage readers to click the medical literature hyperlinks in this article so you can see the data warrants real concern.
Overall, we’ve put the cart before the horse with the hype surrounding the AliveCor Heart Monitor, as is the case with many mHealth devices, by not understanding how we will use the information we gather before touting our ability to gather it in the first place.
We welcome your thoughts, especially your critiques of these points. As with much of mHealth technology, this device is in the earliest stages of its use in healthcare. For mobile health devices to truly succeed, it is important we are able to recognize their appropriate use and also their limitations — otherwise we are only left with their hype, and worse — no improvement in patient outcomes.
As usual, there are no relevant disclosures for iMedicalApps. iMedicalApps does not allow advertising from app developers and has no financial relationships with app developers or mobile hardware companies — unlike every other medical app/device/analyst/review site.
1. Gula, L. J., Krahn, A. D., Massel, D., Skanes, A., Yee, R., & Klein, G. J. (2004). External loop recorders: determinants of diagnostic yield in patients with syncope. American heart journal, 147(4), 644–8. doi:10.1016/j.ahj.2003.10.036
2. Sivakumaran, S., Krahn, A. D., Klein, G. J., Finan, J., Yee, R., Renner, S., & Skanes, A. C. (2003). A prospective randomized comparison of loop recorders versus Holter monitors in patients with syncope or presyncope. The American Journal of Medicine, 115(1), 1–5. doi:10.1016/S0002-9343(03)00233-X