PracticeUpdate: Cardiology | Vol1 - No.2 - 2016

ARRHYTHMIAS/HEART RHYTHM DISORDERS

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App-based technology for atrial fibrillation screening By Abhishek J Deshmukh, MBBS and Paul A Friedman, MD Evolving social and digital media platforms are generating seismic shifts in patient behaviour and creating equally disruptive opportunities for healthcare delivery. T his is an exciting field, and multiple platforms on hand- held devices are empower- App-based technology for diagnosing AF is

on device diagnostics could be detrimental. Putting it all together in practice Inexpensive screening for AF, particularly in individuals with hypertension and diabetes, may permit treatment with anticoagu- lation resulting in stroke preven- tion. The widespread availability of smartphones and ease of use enables frequent, inexpensive screening. As with any screening tool, optimal deployment depends on the population tested. In a relatively low-risk population such as that studied by Chan et al, a positive PPG finding indicates an approximate 50% chance of AF ac- tually being present; so a screening program using the PPGmust have an integrated next step for follow- up. In patients at higher risk for AF (such as those who are post AF ablation), a device that records an ECG tracing is preferable. Unlike AliveCor (which uses electrodes that affix to a smartphone to record an actual ECG that is locally ana- lysed and transmitted) and other devices that transmit ECG tracings to providers who can adjudicate rhythms, PPG recordings do not permit a definitive diagnosis, even when transmitted to physicians for review. ECG diagnosis is essential before institution of therapy such as anticoagulation. The goal of widespread inexpen- sive AF identification for stroke prevention is noble and important. App-based technology for diagnos- ing AF is definitely cool; however, chasing AF in a low-risk patient in the absence of an integrated program to manage false-positive results may send us chasing the elusive Pokemon!

Diagnostic performance of a smartphone-based photoplethysmographic application for atrial fibrillation screening in a primary care setting Journal of the American Heart Association Take-home message • This study assessed the diagnostic per- formance of a smartphone camera-based photoplethysmographic (PPG) applica- tion, Cardiio Rhythm, to screen patients with hypertension, diabetes mellitus, and those aged ≥65 years for AF in the primary care setting. A reference stand- ard was established using the AliveCor heart monitor. Of 1013 patients, 28 were diagnosed with AF. Cardiio Rhythm had a diagnostic sensitivity of 92.9%, higher than that of AliveCor (71.4%). Both screen- ing methods had similar specificities and high negative predictive values, but the positive predictive value of Cardiio Rhythm was lower than that of AliveCor. • The smartphone PPG application Cardiio Rhythm detected AF in patients at risk of developing AF and could be used to en- able population-based screening for AF. Abstract BACKGROUND Diagnosing atrial fibrillation (AF) before ischemic stroke occurs is a prior- ity for stroke prevention in AF. Smartphone camera-based photoplethysmographic (PPG) pulse waveform measurement discriminates between different heart rhythms, but its abil- ity to diagnose AF in real-world situations has not been adequately investigated. We sought to assess the diagnostic performance of a standalone smartphone PPG application, Cardiio Rhythm, for AF screening in primary care setting. METHODS AND RESULTS Patients with hyperten- sion, with diabetes mellitus, and/or aged ≥65 years were recruited. A single-lead ECG was recorded by using the AliveCor heart monitor with tracings reviewed subsequently by 2 cardi- ologists to provide the reference standard. PPG measurements were performed by using the Cardiio Rhythmsmartphone application. AFwas diagnosed in 28 (2.76%) of 1013 participants. The diagnostic sensitivity of the Cardiio Rhythm for AF detection was 92.9% (95% CI] 77–99%) and was higher than that of the AliveCor automated algorithm (71.4% [95%CI 51–87%]). The specifici- ties of CardiioRhythmand theAliveCor automat- ed algorithm were comparable (97.7% [95% CI: 97–99%] versus 99.4% [95% CI 99–100%]). The positive predictive value of the Cardiio Rhythm was lower than that of the AliveCor automated algorithm (53.1% [95% CI 38–67%] versus 76.9% [95% CI 56–91%]); both had a very high nega- tive predictive value (99.8% [95% CI 99–100%] versus 99.2% [95% CI 98–100%]). CONCLUSIONS The Cardiio Rhythm smartphone PPG application provides an accurate and reli- able means to detect AF in patients at risk of developing AF and has the potential to enable population-based screening for AF. J Am Heart Assoc 2016;5:e003428 Chan PH, Wong CK, Poh YC, et al.

ing our patients with access to diagnostic tools at a fraction of the cost of traditional tests. Although acceptance of such technology is likely to be higher in a “non-atrial fibrillation age group,” it offers an opportunity for our patients to have the diagnostic tools in their pockets at all times. In the United States, smartphone ownership among the elderly continues to increase rapidly, with 27% of people age ≥ 65 years and 54% of those aged 50 to 64 years owning a smartphone. Dr Chan and coauthors investi- gated the diagnostic performance of a standalone smartphone app for AF screening in a primary care setting. The Cardiio Rhythm smartphone app determines R-R intervals (and thus the rhythm) by having the user place a finger over the smartphone camera and by using the phone’s LED flash to record a photoplethysmography (PPG) waveform. This requires no equipment beyond the phone itself, making the tool widely available. It accurately identified patients with AF in the primary healthcare setting with a high sensitivity (92.9%) and specificity (97.7%). The authors were able to screen 1098 patients with a history of hypertension and/or diabetes mel- litus or were ≥ 65 years of age. Of 1013 patients, 920 (90.82%) were deemed to be in sinus rhythm based on the two cardiologists’ interpretation of the single-lead ECG recording. AF was diagnosed in 2.76% of patients and confirmed with a standard 12-lead ECG. The false-positive results identified by the Cardiio Rhythm smartphone application were due to sinus rhythm (69.6%), premature atrial contractions (13%), premature

definitely cool; however, chasing AF in a low-risk patient in the absence of an integrated program to manage false-positive

results may send us chasing the elusive Pokemon!

ventricular contractions (13%), and sinus arrhythmia (4.3%) The majority of false positives originat- ed from pulse waveforms that were corrupted by finger movement ar- tifacts that may have affected the detection algorithm, despite use of the app with instruction from trained observers. Is this good news for the patients? With diagnostic testing handy, patients can record symptoms and rhythm and receive real-time feedback. With a negative pre- dictive value of 98.8%, a normal

result is reassuring, sparing ad- ditional medical care. Can it be a double-edged sword? Since diagnostics are from the app itself, there might be more use of the app, increased anxi- ety to look for change in case of “real” or perceived change, and in- creased risk of false-positive find- ings, particularly if the app were used in the community without the benefit of trained observers present. Inappropriate medica- tion changes without consulting with a healthcare provider based

Dr Deshmukh is Electrophysiol- ogy Fellow, Mayo Clinic, Minnesota. Dr Friedman is Vice-Chair, Cardi- ovascular Medi- cine, Mayo Clinic, Medical Director,

Remote Moni- toring, Center for Connected Care, Mayo Clinic, Minnesota.

JOURNAL SCAN Survival after secondary prevention ICD placement Journal of the American College of Cardiology: Clinical Electrophysiology Take-home message

included. Kaplan-Meier survival analysis was used to assess mortality. Cox proportional hazards survival modeling was used to assess the risk of death in these groups, adjusting for patient characteristics. RESULTS In the study cohort of 46,685 patients (mean age 66 ± 14 years, 73.5% male, 85% white), 78% had SCD/VT and 22% had syn- cope. Overall mortality was 10.4% at 1 year and 16.4% at 2 years. Com- pared with patients having SCD/VT, the adjusted hazard of death at 1 year was lower in the patients having syncope (hazard ratio: 0.89; 95% confidence interval: 0.83 to 0.96) but was not significantly different by 2 years (hazard ratio: 0.96; 95% confidence interval: 0.90 to 1.01). CONCLUSIONS Nearly 9 of 10 patients receiving a secondary prevention ICD in clinical practice are alive 1 year after implantation. The risk of death varies by indication and is highest among patients who survive SCD or sustained VT in the first year after device implantation. Survival after secondary prevention implantable cardioverter- defibrillator placement: an analysis from the NCDR ICD Registry. JACC Clin Electrophysiol 2016 Sep 07;[Epub ahead of print], Honarbakhsh S, Baker V, Kirkby C, et al

• This study evaluated the outcomes of ICDs for secondary prevention of sudden cardiac death (SCD). Patients with a physician- designated secondary prevention indication for an ICD and history of tachycardia arrest or sustained ventricular tachycardia (SCD/ VT) or syncope without SCD/VT were selected from the National Cardiovascular Data Registry’s ICD Registry. Mortality in the overall study cohort was 10.4% and 16.4% at 1 and 2 years, respectively. In the syncope group, mortality risk at 1 year (but not at 2 years) was reduced compared with the SCD/VT group (HR, 0.89). • Patients with a history of a tachycardia arrest or sustained VT and an ICD for secondary prevention of SCD have a higher risk of death in the first year following ICD implantation. Abstract

METHODS Patients enrolled in the National Cardiovascular Data Registry’s (NCDR) ICD Registry from 2006 to 2009 with a physician- designated secondary prevention indication for ICD implantation were identified and linked to the Social Security Death Master File. Those patients with a history either of tachycardic arrest or sustained ventricular tachycardia (SCD/VT) or of syncope without SCD/VT were

OBJECTIVES This study sought to define the characteristics and risks of death of patients receiving a physician-designated secondary prevention implantable cardioverter-defibrillator (ICD) in contemporary clinical practice. BACKGROUND Data on utilization and outcomes of ICDs for the second- ary prevention of sudden cardiac death (SCD) are limited.

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