Cardiologist Eric Topol, MD, often shares his compelling story of using a prototype device he happened to be carrying in his pocket to diagnose a fellow passenger on a transcontinental flight with an acute STEMI. As a result, the plane made an emergency landing and the patient received care right away. The device? AliveCor's iPhone ECG case, which received FDA approval in December 2012 and became available to US medical professionals this month.

The growing presence of smartphones and tablets in the health care setting has led to a concomitant rise in apps and devices meant to make diagnostic information available anywhere, more rapidly, and at a lower cost. We've covered many of these in previous columns, but perhaps what makes AliveCor so compelling is its refusal to let its iPhone ECG be branded as a health toy or gimmick. The company pursued Class II Medical Device recognition through the difficult FDA 510(k) approval process, rather than following the direct-to-consumer model chosen by many manufacturers of smartphone-enabled devices. As further evidence of AliveCor's commitment to proving its device's clinical relevance, a poster entitled "iPhone Rhythm Strip—The Implications of Wireless and Ubiquitous Heart Rate Monitoring," which described pilot results from an 8-week study of 54 participants who used the iPhone ECG, was presented at ACC.12.

I first became acquainted with AliveCor and its Oklahoma-based founder, David Albert, MD, in 2011 after he posted a YouTube video demonstrating an early model of the device, which he had conceived of 2 years prior. Later that year I met Dr. Albert at the mHealth Summit and within a few weeks had my own review copy of the device. While it took me a few days to feel comfortable replacing the protective armor of my OtterBox case with the ECG case that offered limited protection (and then, on only one side), it soon became a permanent fixture on my phone. I've since measured one-lead ECGs on myself and dozens of friends and patients, and now have a library of hundreds of recordings of varying amplitude ranging from 15-60 seconds.

Each of these strips can be sent directly to a printer or emailed, thus transforming the device into a real-time event monitor that can be quickly turned on by a patient, for example, whenever he or she is having palpitations. One issue, though, is that the device is sensitive to the slightest movements and disturbances, and usually requires 5-10 seconds for the signal to equilibrate and display a heart rate. The signal can be improved, however, by moistening the two electrodes with ethanol. In terms of battery life, I had to replace the $2 battery once after about 6 months of regular use, but AliveCor claims that its newly approved model can record up to 12,000 30-second ECGs before needing a battery change.

Admittedly the case initially proved more useful as a conversation-starter than a diagnostic tool, but I soon found myself preferentially using it to measure my patients' heart rates. I've placed the two fixed-position electrodes on hundreds of hands, chests, and legs to record leads I, II, III, and various precordial leads, and have detected sinus bradycardia, AF, and—inadvertently—inappropriate sinus tachycardia in one of the deans at my institution. While these individuals already knew about their conditions, Dr. Albert told me after the ACC meeting that they have had an "incredible" diagnostic yield with the iPhone ECG, explaining that they "diagnosed ventricular tachycardia in a previously asymptomatic 35-year old man; a new case of Wolff-Parkinson-White syndrome in a 41-year old man, who is now being ablated; paroxysmal supraventricular tachycardia in a 20-year-old college athlete who had been blown off by her coaches; and atrioventricular nodal reentry tachycardia in a 17-year-old congenital heart patient who was not diagnosed after a 2-week Holter study."

AliveCor has since presented additional validation studies at the 2012 Heart Rhythm Society and AHA meetings, and, according to Dr. Albert, is currently conducting research to explore the device's utility in post-ablation follow-up, medication-induced QT duration response monitoring, preventive pediatric care, and long-term AF remote monitoring, just to name a few. Until these results come out, some remain skeptical about the clinical utility of a one-lead ECG and wonder if the hype is justified. Silicon Valley certainly believes so: AliveCor has received close to $15 million in funding from heavy-hitters such as Burrill & Company, Qualcomm Ventures, and Khosla Ventures, and the team has grown to about three dozen people in less than a year.

At this point, the ECG case is retailing for $199 and is compatible with the iPhone 4 and 4S running iOS 5.1, and they are working on adapting the case for other smartphones. And though the company has been secretive about future potential product offerings, based on their demo at the mHealth Summit they may be interested in developing additional cardio monitoring tools and improving upon or expanding their current offering. They have been selling the iPhone ECG case for veterinary purposes for months now, and in the future they may explore adding more movable electrodes, as well as developing software that can aid with the analysis of rhythm strips.

Regardless of what happens with AliveCor's device, the transformation that cardio technology has taken, since Willelm Einthoven recorded his first electrocardiographs almost 100 years ago using a machine that weighed 600 pounds and required five people to operate, is remarkable. We can hope that 2013 brings with it even greater developments.

Shiv Gaglani is an MD/MBA candidate at the Johns Hopkins School of Medicine and Harvard Business School. He writes about trends in medicine and technology and has had his work published in Medgadget, The Atlantic, and Emergency Physicians Monthly.

Keywords: Electrodes, Tachycardia, Ventricular, Wolff-Parkinson-White Syndrome, Ethanol, Tachycardia, Atrioventricular Nodal Reentry, Tachycardia, Sinus, Bradycardia, Electrocardiography, Heart Rate, ACC Publications

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