April 2024 Issue

Wearables and Apps: Heart Health Apps Gain Traction
By Elizabeth S. Goar
Today’s Dietitian
Vol. 26 No. 4 P. 8

Tech Is Expanding RDs’ Potential to Help Patients and Collaborate With Physicians

CVD is the leading cause of death in the United States, claiming about 695,000 lives—or one in every five deaths.1 Meanwhile, about 40% of US adults use health care–related applications, such as medication tracking or nutrition apps, and 35% use wearable health care devices, such as those from Fitbit, as well as continuous glucose, blood pressure (BP), and heart monitors from other brands.2

Together, these statistics form a clear picture of why the market for heart health apps and wearables is booming, and interest in and evidence to support integrating them more purposefully into clinical practice is growing.

“Heart rate and blood pressure monitoring apps prove to be invaluable assets for RDs seeking to elevate patient care and tailor dietary and lifestyle guidance for clients aiming to achieve specific health objectives, such as managing blood pressure,” says Michelle Routhenstein, MS, RD, CDCES, CDN, who specializes in CVD at EntirelyNourished.com in New York City. “RDs can leverage real-time data from these apps to customize nutrition plans, establish and monitor health goals, and evaluate the influence of dietary modifications on blood pressure level, heart rate, and heart rhythm.”

Crowded Market
As mobile technology expands due to these benefits, so does the number and types of wearables available to consumers and clinicians. Falling under the regulatory purview of the FDA, heart health apps and mobile devices existing today range “from simple tracking apps to more advanced ones with special features like real-time electrocardiogram (ECG) monitoring, personalized health insights, and integration with other health metrics,” Routhenstein says.

Mobile health apps and wearables fall into the following three categories:

1. Patient-facing technology for self-care, including devices that monitor and record health statuses like glucose levels and BP or direct specific actions such as alerts for medication adherence.

2. Clinician-facing technology providing medical education or information from a treatment perspective and/or assisting with diagnosis or preventive care, such as calculating stroke risk factor scores.

3. Hybrids between patient- and clinician-facing technology that share data such as patient-measured heart rate, BP, or ECG readings.3

The data wearables collect is automatically recorded and stored on the device or synced to an associated app, where it can be stored locally or in the cloud. Some wearables also permit recorded data to be electronically shared with other apps or the user’s health care professional.

However, it’s important to remember that these technologies are tools, and tools have a specific time and purpose. For instance, heart rate apps are among the most popular and are frequently integrated with fitness trackers. From a clinical perspective, however, they’re also among the least important, according to Andrew Freeman, MD, FACC, cochair and cofounder of the American College of Cardiology Nutrition and Lifestyle Workgroup.

“Everybody’s obsessed with heart rate monitoring, but just because you can measure something doesn’t necessarily mean you need to,” he says. “For the vast majority of people, unless they’re becoming very elite or competitive athletes or we’re looking for specific arrhythmia, heart rate monitoring may not be all that important.”

Smartphone heart rate apps use the camera to automatically detect and record changes in color and opacity as blood is pumped through the skin.

Heart rate devices include pulse oximeters that clip onto a fingertip and use red and infrared light to measure and record blood oxygen levels. Some nonprescription versions—which aren’t cleared by the FDA—sync that information with associated apps. Chest band monitors use a strap embedded with sensors to measure and record direct heart rate. Because they directly measure the heart rate rather than pulse rate, chest bands are the most accurate—but least convenient—option.

Currently, BP self-monitoring is limited to cuffs that connect wirelessly to apps that automatically store and share data. While popular, BP cuffs, in general, suffer from inaccuracy. However, personal cuffs have an advantage over those used in medical offices because they eliminate “white coat anxiety” that can artificially increase a patient’s BP and allow levels to be checked throughout the day for a more accurate longitudinal picture, Freeman says.

“BP [readings] that we get in the office are notoriously inaccurate or not always representative of what somebody’s real blood pressure is,” he says, adding that he recommends using the website ValidateBP.org to determine whether a cuff has been validated for efficacy and reliability.

A third type of heart health app is an ECG monitor, which measures the timing and strength of electrical signals that cause the heart to beat and is used to detect atrial fibrillation (AF or AFib)—when the heart beats chaotically. Most wearable ECG monitors work via external sensor pads that sync with a smart device to collect the data; however, both Apple and Samsung smartwatches have integrated ECG functionality that uses embedded sensors to measure and record electrical signals.

According to Freeman, consumer-facing ECG wearables are a “fantastic technology” that, while not yet medical grade, is particularly useful for anyone at risk of AF or who’s predisposed to stroke.

Efficacy and Accuracy Vary
While most heart health apps earn high marks for convenience, research suggests that accuracy varies significantly.

For example, pulse oximeter accuracy depends largely on blood oxygen levels; they’re most accurate when saturation is at least 90% (healthy levels typically are between 95% and 100%) and are least accurate when it’s lower than 80%.4 In addition, while one study found that portable devices are accurate enough to be clinically useful, another found that the 10 top-selling consumer devices aren’t reliable when it comes to confirming hypoxemia (low blood oxygen levels).5,6

Several other recent studies suggest that accuracy of pulse oximeters may be impacted by skin tone. In one case, researchers found that readings from prescription devices were artificially higher in nonwhite patients,7 while another study found that Black patients were three times more likely than white patients to have occult hypoxemia go undetected by the devices.8

In terms of BP apps, research findings are conflicting regarding their usefulness. One study found that using a smartphone-connected BP monitor with clinically based digital coaching maintained lower BPs for as long as three years.9 Another, however, concluded that using a device paired with a smartphone app wasn’t more effective.10

For ECG apps, study findings also are mixed. In one case, researchers concluded that their use is challenging in patients with abnormal ECGs, although better algorithms and machine learning might improve accuracy.11 Another study found that smartphone-based ECG recorders are five times more effective at diagnosing heart rhythm problems than standard tests and also reduced associated diagnostic costs.12

What’s important, Freeman says, is understanding the limitations when it comes to accuracy and efficacy of today’s heart health apps and taking steps to help maximize their effectiveness. He also recommends calibrating any app or devices against what’s used in the doctor’s office.

“At the end of the day, I think things are getting … pretty reliable overall, but there’s still a lot of cheap and less reliable technology out there that contaminates the field,” Freeman adds, noting that beyond the ValidateBP.org website for BP cuffs, there’s really “no way of knowing, other than price points, which [apps and devices are reliable]. Even then, I’ve gotten some expensive ones that were just absolutely [awful].”

Integrating Apps Into Clinical Practice
RDs can make meaningful use of heart health apps by collaborating with patients’ physicians and making recommendations based on the data these tools gather, Routhenstein says. For example, in cases of low or borderline low BP accompanied by symptoms like lightheadedness, BP app data can assist the physician in making medication adjustments.

“The focus,” Routhenstein says, “should be on clear communication, respecting patient consent, and delivering insightful information to support informed decision-making within the health care team.”

Freeman singles out BP management as an area in which RDs using technology can have a significant impact. Particularly, the impact of eating a predominantly plant-based diet has been shown to significantly lower BP—sometimes as good as or better than medications.

“If I was an RD working with someone with high blood pressure who doesn’t want to take a lot of medications or wants to get off their medications, getting them to lose weight, exercise, eat differently, and then [showing them] the effects of those interventions on blood pressure readings relatively quickly would be pretty tremendous,” Freeman says.

While there are no established guidelines for how to integrate heart health apps into practice, Routhenstein recommends looking for apps that have been validated and tested for accuracy. Also, “check if they provide information on the methodologies used for measurements and whether [those methodologies] align with established standards,” she says.

The American Heart Association offers patient education resources, including how to properly measure heart rate and monitor BP. Available materials also include information on the difference between pulse and BP.

Integrating ECG monitors is another potentially impactful addition to an RD’s practice as “there are some significant conversations [taking place] about diet and weight loss for reducing AFib,” Freeman says.

Along with a diet rich in fruits, vegetables, whole grains, and lean proteins, patients with AF are advised to limit or avoid added sugars, saturated and trans fats, and alcohol. Depending on what blood thinner they’re prescribed, AF patients also may be advised to stay consistent with eating leafy green vegetables, as fluctuating levels of vitamin K can change how some medications work in the body.

Freeman also suggests having patients pair heart health monitors with other time-tested tools like nutrition and fitness apps, which “will make RDs’ work more reliable. Combining patient wearables, vitals, and other data [they gather] could really make a big push for how important lifestyle programs are to modern medicine.”

Sharing data with a patient’s physician remains problematic. While some remote monitoring companies have figured out how to interface with the patient’s EMR, it remains “a hodgepodge of things,” Freeman says.

Nonetheless, he advises RDs to collaborate with their patients’ physicians to determine how best to share self-monitoring data, as doing so will ultimately lead to better outcomes.

“It takes a village to take care of people these days, and using technology to connect the team—RDs and cardiologists—is a great way to provide better patient care,” Freeman says. “The number of referrals from cardiology to RDs is nowhere near where it should be, and this might be a great opportunity to collaborate better.”

— Elizabeth S. Goar is a freelance health writer based in Benton, Wisconsin.


1. Heart disease and stroke prevention. New York State Department of Health website. https://www.health.ny.gov/diseases/cardiovascular/heart_disease/#:~:text=About%20695%2C000%20people%20die%20of,Americans%20have%20a%20heart%20attack. Updated October 2023. Accessed February 2, 2024.

2. Zipp R. The public’s use of health apps and wearables has increased in recent years. but digital health still has room to grow. Morning Consult website. https://pro.morningconsult.com/trend-setters/use-of-digital-health-apps-wearables-growing. Published February 21, 2023. Accessed February 2, 2024.

3. Marvel F, Dowell P, Mossburg S. Emergence of application-based healthcare. perspectives on safety. Agency for Healthcare Research and Quality website. https://psnet.ahrq.gov/perspective/emergence-application-based-healthcare. Published August 5, 2022.

4. National Institute of Biomedical Imaging and Bioengineering. Getting an accurate read on pulse oximeters. MedlinePlus Magazine. https://magazine.medlineplus.gov/article/getting-an-accurate-read-on-pulse-oximeters. Published January 13, 2024,

5. Schrading WA, Page DB. Portable, consumer-grade pulse oximeters are accurate for home and medical use: Implications for their use in patients with COVID-19. Ann Am Thorac Soc. 2021;18(7):1260-1261.

6. Harskamp RE, Bekker L, Himmelreich JCL, et al. Performance of popular pulse oximeters compared with simultaneous arterial oxygen saturation or clinical-grade pulse oximetry: a cross-sectional validation study in intensive care patients. BMJ Open Respir Res. 2021;8(1):e000939.

7. Gottlieb ER, Ziegler J, Morley K, Rush B, Celi LA. Assessment of racial and ethnic differences in oxygen supplementation among patients in the intensive care unit. JAMA Intern Med. 2022;182(8):849-858.

8. Sjoding MW, Dickson RP, Iwashyna TJ, Gay SE, Valley TS. Racial bias in pulse oximetry measurement. N Engl J Med. 2020;383(25):2477-2478.

9. Gazit T, Gutman M, Beatty AL. Assessment of hypertension control among adults participating in a mobile technology blood pressure self-management program. JAMA Netw Open. 2021;4(10):e2127008.

10. Pletcher MJ, Fontil V, Modrow MF, et al. Effectiveness of standard vs enhanced self-measurement of blood pressure paired with a connected smartphone application: a randomized clinical trial. JAMA Intern Med. 2022;182(10):1025-1034.

11. Are smartwatch health apps to detect atrial fibrillation smart enough? ScienceDaily website. https://www.sciencedaily.com/releases/2022/10/221012103146.htm. Published October 12, 2022. Accessed February 4, 2024.

12. Smartphone ECG could be used in A&E to detect serious heart conditions. British Heart Foundation website. https://www.bhf.org.uk/what-we-do/news-from-the-bhf/news-archive/2019/march/smartphone-ecg-could-be-used-in-ae-to-detect-serious-heart-conditions. Published March 4, 2019. Accessed February 4, 2024.