Miguel Ángel Cobos Gil, MD, PhD
Acknowledgment: The author thanks Paloma del Álamo for providing the Apple Watch; Javier Cobos del Álamo for language corrections; Luisa Lozano Gallego and Ana Martín Gómez for recording the ECGs; and José Luis de Unzueta, José Juan Gómez de Diego, Daniel Morales Salinas, and Angela McInerney for contributing to the video.
Disclosures: The author has disclosed no conflicts of interest. The form can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M19-2018.
Reproducible Research Statement:Study protocol: See the Supplement. Statistical code: Not available. Data set: Available from Dr. Miguel Ángel Cobos Gil (e-mail, email@example.com).
Method to record the CR leads.
The back of the watch is placed on the precordium, and the digital crown is touched by a right-hand finger. Artwork by Anna Magda Sajek Tuleja, based on the Michelangelo's frescoes in the Sistine Chapel. CR = chest–right arm.
Electrocardiograms obtained using the Apple Watch versus conventional electrocardiography from a healthy person (the author) (top), a patient with non–ST-segment elevation myocardial infarction (middle), and a patient with ST-segment elevation myocardial infarction (bottom).
All of the standard limb leads (I, II, and III) are identical, and the precordial leads (V1 to V6 vs. CR1 to CR6) bear a great resemblance. CR = chest–right arm.
In this video, Miguel Angel Cobos Gil, MD, PhD, offers additional insight into the article, "Standard and Precordial Leads Obtained With an Apple Watch."
Dr Brian White-Guay
University of Montreal
November 26, 2019
Beware of patients with ICDs or pacemakers
We welcome this innovative application of the Apple Watch to extend standard and precordial leads activity measurement.We would suggest however that caution be exercised in patients with a heart device such as ICD,CRT or pacemaker in light of the risks of interference until further experience is obtained.
Miguel Ángel Cobos Gil, MD, PhD
Hospital Clínico San Carlos
December 9, 2019
Dear Dr White-Guay:
Thank you for your comment. An official document from Apple (1) states that “Apple Watch contains components and radios that emit electromagnetic fields. Apple Watch contain[s] magnets. These electromagnetic fields and magnets may interfere with medical devices, such as pacemakers and defibrillators. Consult your physician and medical device manufacturer for information specific to your medical device. Stop using Apple Watch if you suspect they are interfering with your medical device.” Thus, although I have seen several patients with pacemakers wearing Apple Watches, and recording ECG without problems, your word of caution seems sensible.
1. Important safety information for Apple Watch. Accessed at https://support.apple.com/en-gb/guide/watch/apdcf2ff54e9/watchos on 7 december 2019.
Peter W. Macfarlane
Peter W. Macfarlane, Emeritus Professor, University of Glasgow, Institute of Health and Wellbeing, New Lister Building, Royal Infirmary, Glasgow G31 2ER, Scotland.
December 23, 2019
Apple Watch for Precordial Leads
Apple Watch for Precordial Leads (Published 26th November, 2019 DOI: 10.7326/M19-2018)I read with interest the paper by Dr Gil pointing out how a bipolar chest lead could be recorded using the Apple Watch Series 4 and 5 (1). I thank him for referring to my own description of such leads (2). While I accept that it is indeed feasible to record a bipolar chest leads, in this case CR leads, using the Apple Watch, it is evident from the examples that there are differences in amplitudes of all components of the ECG waveform between the standard precordial leads and the bipolar CR leads. These may be irrelevant in looking for gross change but could lead to discrepancies if recommended criteria are to be used in decision making such as for an acute myocardial infarction (3). Muhlestein et al (4) used the single channel AliveCor device for this purpose in 2015. An even bigger concern which this author would have is that placement of precordial leads more often than not leaves much to be desired. I recently pointed out a case of gross error in positioning of the 10 electrodes used to record a 12 lead ECG (5) in a hospital and posted on social media, and I dread to think what might happen if inexperienced individuals were to be encouraged to record bipolar chest leads using the Apple Watch at “anytime and anywhere” as suggested.Technology is such nowadays that a complete 12 lead ECG can be recorded using a very small electrode/amplifier system linked to a mobile telephone with the appropriate App downloaded. A complete interpretation can even be obtained using such a device. If a medical professional wishes to have the capability of utilising low weight, easily portable equipment for recording a 12 lead ECG, then I would venture to suggest that while the Apple Watch can be used to record leads singly in the manner described by Dr Gil, there are much better methods available which I believe would best be used by professionals. References:1. Gil MAC. Standard and precordial leads obtained with an Apple Watch. Ann Int Med 2019; DOI: 10.7326/M19-20182. Macfarlane PW. Lead Systems. In: Comprehensive Electrocardiology. Eds. PW Macfarlane, A van Oosterom, O. Pahlm et al. Springer, London. 2011. Vol 1. pp377-425.3. Thygesen K, Alpert JS, Jaffe AS et al. Fourth Universal Definition of Myocardial Infarction. Circulation. 2018;138:e618–e651 4. Muhlestein JB, Viet Le PA, Albert D et al. Smartphone ECG for evaluation of STEMEI: Results of the ST LUIS pilot study. J electrocardiol 2015;48:249-59.5. Macfarlane PW, Malik M. ECG electrode positioning deserves better attention. https://blogs.bmj.com/bmj/2018/12/19/macfarlane-and-malik-ecg-electrode-positioning-deserves-proper-attention/ Read 23rd Dec 2019.
Miguel Angel Cobos Gil, MD, PhD
January 7, 2020
Authors' Response to Macfarlane
We appreciate Dr. Macfarlane’s thoughtful comments on my recent article in Annals of Internal Medicine(1).Dr. Macfarlane notes that “it is evident [...] that there are differences [...] between the standard precordial leads and the bipolar CR leads”. I agree. It’s evident and mathematically obliged since CRn = Vn - ⅔ aVR. However, in practice, as my examples, and the literature have shown(2, 3), the CR leads have enough diagnostic potential to detect significant ST abnormalities.We could not agree more about the importance of a correct placement of the precordial leads and patient education is mandatory to use my method of ECG self-recording.Dr. Macfarlane notes that a dedicated ECG kit, linked to an App in a smartphone, can be a better method to record a complete 12 leads ECG. That’s is true. However, how many of such ECG kits, are there now? Not many. Meanwhile, there are now (probably) around fifteen million people wearing an “ECG machine” on their wrist, and the ability to obtain a “self ECG” anytime and anywhere will change our approach to patients with known or suspected heart disease. REFERENCES 1. Cobos Gil MÁ. Standard and Precordial Leads Obtained With an Apple Watch. Annals of Internal Medicine. 2019.2. Muhlestein JB, Le V, Albert D, Moreno FL, Anderson JL, Yanowitz F, et al. Smartphone ECG for evaluation of STEMI: results of the ST LEUIS Pilot Study. J Electrocardiol. 2015;48(2):249-59.3. De Gasperi RN, McCulloh DH. CR leads in cardiac emergencies. A preliminary study. Chest. 1991;99(4):904-10.
Cobos Gil MÁ. Standard and Precordial Leads Obtained With an Apple Watch. Ann Intern Med. 2019;:. [Epub ahead of print 26 November 2019]. doi: https://doi.org/10.7326/M19-2018
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Published: Ann Intern Med. 2019.
Acute Coronary Syndromes, Cardiac Diagnosis and Imaging, Cardiology, Coronary Heart Disease, Emergency Medicine.
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