In the Journals

Mobile cardiac monitoring system predicts AF similarly to ECG

Khaldoun G. Tarakji

A mobile cardiac monitoring system detected atrial fibrillation in patients comparable to 12-lead ECGs when automated interpretation was provided, according to a study published in HeartRhythm.

“This study is the first independent validation of this smartphone monitor system in the clinical setting using near simultaneous 12-lead ECGs,” Khaldoun G. Tarakji, MD, MPH, staff physician in the section of cardiac pacing and electrophysiology, Robert and Suzanne Tomsich Department of Cardiovascular Medicine, Sydell and Arnold Miller Family Heart & Vascular Institute at the Cleveland Clinic, and a Cardiology Today Next Gen Innovator, said in a press release. “In addition to providing an instantaneous rhythm interpretation, this smartphone monitor system is able to transmit a recording to a secure server where the recordings can be directly reviewed.”

Amila D. William, MD, of the department of cardiovascular medicine at Cleveland Clinic, and colleagues analyzed data from 52 patients (mean age, 68 years; 67% men) with a history of persistent or paroxysmal AF who were admitted for the initiation of antiarrhythmic drugs. Patients also had a baseline corrected QT interval less than 470 ms or 500 ms with a QRS duration greater than 120 ms.

Patients were given a mobile cardiac monitoring system (Kardia, AliveCor) with a WiFi-enabled smart device (iPod, Apple) while admitted for antiarrhythmic drug initiation, when patients were given sotalol or dofetilide twice per day for six monitored doses. After each dose, patients underwent a 12-lead ECG. Electrical cardioversion was performed in patients who were in AF after the fourth dose.

According to the researchers, the mobile cardiac monitoring system has an algorithm that automatically reads the rhythm strip and interprets it as normal, possible AF or unclassified.

Of the 225 simultaneous 12-lead ECG and mobile cardiac monitoring system recordings, 27.6% were considered unclassified according to the mobile cardiac monitoring system algorithm.

Readings comparable

After excluding the unclassified readings, the automated algorithm interpretation had 94.1% specificity and 96.6% sensitivity vs. physician-interpreted 12-lead ECGs (kappa coefficient = 0.89; 95% CI, 0.82–0.97). Mobile cardiac monitoring system recordings interpreted by physicians had 100% sensitivity and 89.2% specificity compared with ECGs read by physicians (kappa coefficient = 0.85; 95% CI, 0.78–0.92).

Of the unclassified mobile cardiac monitoring system recordings, 57 were able to be interpreted by physicians, which had 100% sensitivity and 79.5% specificity compared with 12-lead ECG interpretations (kappa coefficient = 0.71). Physician-interpreted mobile cardiac monitoring system recordings had a false-negative rate of 0% and a false-positive rate of 20.5%.

“Given the predefined algorithm operating parameters and high rate of ‘unclassified’ recordings with resultant missed AF instances, the [Kardia Mobile Cardiac Monitor] algorithm is not suited to be a replacement for physician analysis,” William and colleagues wrote. “However, given its highly accurate performance when able to provide an interpretation, it holds potential as an adjunct to clinical decision making. The [Kardia Mobile Cardiac Monitor] provides patients and clinicians with a noninvasive and longitudinal modality to assess the presence of AF.”

Guidance on best use

Physicians should consider these products complementary, Tarakji said in the release.

“The ability to record your own rhythm strip and directly visualize it and share it with your physician was fictional up until a few years ago. We live in an exciting era in which technology is evolving at an unprecedented pace. As a medical community, we have a duty to test these products, assess their accuracy, and more importantly, examine their ability to change outcomes. Abundance of data could become noise if it does not come with guidance about proper management of the information. Our obligation through proper clinical studies is to provide guidance about the best use of these tools. As physicians, we should not view these products as threats, but rather as an opportunity to provide better and more effective care for our patients,” he said. – by Darlene Dobkowski

Disclosures: The Kardia Mobile Cardiac Monitors and iPods used in this study were provided by AliveCor. William reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.

Khaldoun G. Tarakji

A mobile cardiac monitoring system detected atrial fibrillation in patients comparable to 12-lead ECGs when automated interpretation was provided, according to a study published in HeartRhythm.

“This study is the first independent validation of this smartphone monitor system in the clinical setting using near simultaneous 12-lead ECGs,” Khaldoun G. Tarakji, MD, MPH, staff physician in the section of cardiac pacing and electrophysiology, Robert and Suzanne Tomsich Department of Cardiovascular Medicine, Sydell and Arnold Miller Family Heart & Vascular Institute at the Cleveland Clinic, and a Cardiology Today Next Gen Innovator, said in a press release. “In addition to providing an instantaneous rhythm interpretation, this smartphone monitor system is able to transmit a recording to a secure server where the recordings can be directly reviewed.”

Amila D. William, MD, of the department of cardiovascular medicine at Cleveland Clinic, and colleagues analyzed data from 52 patients (mean age, 68 years; 67% men) with a history of persistent or paroxysmal AF who were admitted for the initiation of antiarrhythmic drugs. Patients also had a baseline corrected QT interval less than 470 ms or 500 ms with a QRS duration greater than 120 ms.

Patients were given a mobile cardiac monitoring system (Kardia, AliveCor) with a WiFi-enabled smart device (iPod, Apple) while admitted for antiarrhythmic drug initiation, when patients were given sotalol or dofetilide twice per day for six monitored doses. After each dose, patients underwent a 12-lead ECG. Electrical cardioversion was performed in patients who were in AF after the fourth dose.

According to the researchers, the mobile cardiac monitoring system has an algorithm that automatically reads the rhythm strip and interprets it as normal, possible AF or unclassified.

Of the 225 simultaneous 12-lead ECG and mobile cardiac monitoring system recordings, 27.6% were considered unclassified according to the mobile cardiac monitoring system algorithm.

Readings comparable

After excluding the unclassified readings, the automated algorithm interpretation had 94.1% specificity and 96.6% sensitivity vs. physician-interpreted 12-lead ECGs (kappa coefficient = 0.89; 95% CI, 0.82–0.97). Mobile cardiac monitoring system recordings interpreted by physicians had 100% sensitivity and 89.2% specificity compared with ECGs read by physicians (kappa coefficient = 0.85; 95% CI, 0.78–0.92).

Of the unclassified mobile cardiac monitoring system recordings, 57 were able to be interpreted by physicians, which had 100% sensitivity and 79.5% specificity compared with 12-lead ECG interpretations (kappa coefficient = 0.71). Physician-interpreted mobile cardiac monitoring system recordings had a false-negative rate of 0% and a false-positive rate of 20.5%.

“Given the predefined algorithm operating parameters and high rate of ‘unclassified’ recordings with resultant missed AF instances, the [Kardia Mobile Cardiac Monitor] algorithm is not suited to be a replacement for physician analysis,” William and colleagues wrote. “However, given its highly accurate performance when able to provide an interpretation, it holds potential as an adjunct to clinical decision making. The [Kardia Mobile Cardiac Monitor] provides patients and clinicians with a noninvasive and longitudinal modality to assess the presence of AF.”

Guidance on best use

Physicians should consider these products complementary, Tarakji said in the release.

“The ability to record your own rhythm strip and directly visualize it and share it with your physician was fictional up until a few years ago. We live in an exciting era in which technology is evolving at an unprecedented pace. As a medical community, we have a duty to test these products, assess their accuracy, and more importantly, examine their ability to change outcomes. Abundance of data could become noise if it does not come with guidance about proper management of the information. Our obligation through proper clinical studies is to provide guidance about the best use of these tools. As physicians, we should not view these products as threats, but rather as an opportunity to provide better and more effective care for our patients,” he said. – by Darlene Dobkowski

Disclosures: The Kardia Mobile Cardiac Monitors and iPods used in this study were provided by AliveCor. William reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.

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