Mobile Health Applications in Cardiac Care

Enone Honeyman; Hang Ding; Marlien Varnfield; Mohanraj Karunanithi


Interv Cardiol. 2014;6(2):227-240. 

In This Article

Mobile Health in Cardiac Intervention & Management

Mobile health offers significant, mainly untapped, potential to improve cardiac care from both a patient and a clinical perspective, at every stage of the patient's care journey and in all care locations, with some potential applications highlighted in Figure 2. In this section, we describe and highlight some of the key cardiac interventions where mobile health has been applied or studied in both the acute and longer-term care settings.

Figure 2.

Potential applications of mobile technologies by patients and clinicians at each stage of the care journey.
AED: Automated external defibrillator; app: Application; EMR: Electronic medical record; OHCA: Out-of-hospital cardiac arrest.

These applications include recent advances and some established programs involving mobile health in cardiac arrest, arrhythmias, myocardial infarction (MI) and heart failure (HF) monitoring and management.

Mobile Health in Cardiac Arrest

It is well known that survival to hospital discharge following an out-of-hospital cardiac arrest (OHCA) in a public location is significantly improved through early cardiopulmonary resuscitation (CPR) and defibrillation.[14] Several initiatives have evaluated how healthcare workers' and the public's ubiquitous access to mobile phones can strengthen each link within the chain of survival,[15] with Kovic suggesting a mobile chain of survival,[16] illustrated in Figure 3. Using a mobile phone to contact emergency services in life-threatening situations has already been correlated to improved outcomes when compared with landline contact.[17] Furthermore, application of mobile technologies in the support of CPR training and implementation has been reported in several studies, which are described below.

Figure 3.

Mobile Chain of Survival© by Ivor Kovic.
CPR: Cardiopulmonary resuscitation.

A study involving healthcare professionals and laypeople showed improved cardiac compression rate over 2 min when supported by self-directed CPR training with feedback delivered through a smartphone app in a cardiac arrest simulation, compared with when not using the app, as well as acceptability of the technology.[18] Another study showed lay responders (LRs) receiving CPR and automated external defibrillator (AED) training had improved retention of skills through accessing a video clip via their mobile phone, which they were repeatedly encouraged to watch by SMS text message.[19]

Dispatcher-assisted CPR simulation studies have shown improved confidence[20] and technique[21–23] in bystander CPR when dispatch instructions were accompanied by mobile phone-based video or animation demonstration. Improvements in technique included better rate and depth of chest compressions, correct hand positioning and reduced hands-off events during resuscitation. Even a simple audio program[24] providing CPR instruction increased bystander CPR technique in manikin simulations in 178 subjects. Similarly, advanced life support (ALS)-certified doctors showed improved ALS performance in a simulated medical emergency[25] during a randomized controlled trial (RCT) study when using the Resuscitation Council UK's iResus© app on a smartphone.

The Mobile Life Saver (MLS)[26] is a mobile phone service that uses mobile phone positioning systems to dispatch CPR-trained LRs to nearby suspected OHCA. In a real life RCT study in Stockholm, MLS LRs arrived before the ambulance in 45% of all suspected and 56% of all true OHCAs, performing CPR in 17 and 30% respectively. This demonstrates the potential life-saving role mobile phones can play in ensuring the earliest possible CPR.

Early defibrillation significantly improves survival in OHCA. Sakai et al.[27] developed and tested a novel mobile AED map, which allowed easier access to registered AEDs via mobile phone in emergency situations. Even though their findings did not shorten time to accessing AEDs in a simulated emergency, it significantly reduced the travel distance to access and retrieve the AED. With further technological improvements in mobile location positioning, the system is likely to improve AED usage in emergency situations.

Mobile Health in Arrhythmias

The prevalence of arrhythmias is increasing with an aging population. Various methods exist for the detection and ongoing monitoring of arrhythmias, which is essential in enhancing patient safety and providing optimal care. Patient choice and compliance, clinical indication and cost all play a role in deciding the most appropriate method, as no single option is ideal in every clinical scenario.[28] Although continuous-wear external monitors and implantable devices with atrial ECG analysis capability are most accurate in arrhythmia detection, alternatives have to be available to provide choice and mitigate high cost, risks and compliance issues with these devices.[28]

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and is associated with a risk of serious sequelae, including stroke, HF and mortality.[29] It can be asymptomatic or associated with nonspecific symptoms, and is often paroxysmal and short-lived. Accurate and easily accessible methods for detection and monitoring of AF are required.[30] McManus et al.[31] developed a novel iPhone 4S application analyzing pulsatile time series from recordings using the phone's inbuilt camera placed directly on a finger, and tested it in a prospective cohort study involving 76 hospitalized patients with AF pre- and post-cardioversion. They were able to accurately distinguish between AF and normal sinus rhythm. Although further studies are required to test accuracy, acceptability and feasibility in a real-world environment and include a broader spectrum of arrhythmias, it holds promise as a readily available, user-friendly and cheap tool for assisting in diagnosis and monitoring of AF and eventually other arrhythmias, in real time and on a variety of mobile devices. Similarly, the US FDA-approved AliveCor iPhone ECG device,[32] which has two metal electrodes on the back of the phone case that record heart rhythms when held by a user with both hands or placed against their chest, has a demonstrated 98% sensitivity and 97% specificity for automated diagnosis of AF against 12-lead ECG, making it a potential tool for AF screening in the wider population at low cost.

Gussak et al.[28] tested a wireless handheld monitor capable of 12-lead ECG reconstruction for arrhythmia detection rate compared with serial Holter monitoring in 25 patients following AF ablation procedure over a 6-month period. They demonstrated that wireless monitoring was more sensitive than periodic Holter monitoring in detecting AF and atrial flutter (AFL). The system detected both symptomatic and asymptomatic AF and AFL during daily remote monitoring (RM) and enabled differential diagnosis of symptomatic arrhythmias. Patients complied well with the monitoring schedule, suggesting acceptance of the device.

Lin et al.[33] described the development of an ambulatory, real-time and autoalarm intelligent telecardiology system, consisting of a lightweight, power-saving wireless ECG device that communicates via Bluetooth to a mobile device. The mobile device transmits an alert to a remote server if ECG abnormalities are detected and can trigger an emergency medical alarm system when required. In testing, they were able to correctly identify AF, sinus tachycardia, sinus bradycardia, wide QRS complex and cardiac asystole with approximately 94% accuracy in 30 patients tested. Similarly, HeartSaver[34] is a mobile medical device developed for real-time monitoring of a patient's ECG, which automatically identifies several cardiac pathologies, including AF, MI and atrioventricular block through detection algorithms. When an abnormality is detected via the device's sensor and ECG processing unit, a microcontroller sends a signal to a cell phone triggering an app to send a text message with the patient's condition and location to a nominated recipient (e.g., carer or healthcare professional). The inclusion of the patient's GPS location is a novel idea and important in locating individuals quicker in case of emergency.

In Italy, a study[35] of an emergency medical service (EMS) aimed at reducing Emergency Department (ED) time to diagnosis described the use of prehospital ECG assessment transmitted via mobile phone to a 24/7 telemedicine support hub, where a cardiologist provided ECG interpretation. ECGs were transmitted back to the EMS team or cardiologist on their smartphones. They found that, in 27,841 consecutive EMS patients screened with prehospital ECG for suspected heart disease between October 2004 and April 2006, the rate of at-home AF diagnosis increased from twofold (in 40-year-olds) up to sevenfold (in 70-year-olds). Of the 27,841 EMS patients, syncope was reported in 2,648 patients[36] and, in just under 2% of these patients, serious cardiac rhythm abnormalities requiring urgent cardiology admission were identified, leading to potential reductions in wrong diagnoses and treatment delays. Furthermore, Shacham et al.[37] reviewed medical records on 649 patients (1886 episodes) who contacted a 24/7 subscription telemedical system who had an episode of paroxysmal AF (PAF) over several years. All subscribers to the system were provided with a cardiobeeper capable of transmitting a three- or 12-lead ECG via a mobile phone, thereby giving them virtually unlimited access to the system's medically staffed call center irrespective of their location. They found that 80% of PAF episodes could be managed successfully out of hospital, thereby ensuring prompt and safe management and reducing unnecessary visits to EDs and hospitalizations.

Cardiovascular implantable electronic devices (CIEDs) are being used for increasingly wider arrhythmia indications and many, including PMs, implantable cardioverter defibrillators (ICDs), implantable cardiac resynchronization therapy (CRT) devices, insertable cardiac monitors (ICMs), can be interrogated remotely.[38] Data downloaded from the device via the built-in transmitter are communicated via a landline or, increasingly, via mobile Global System for Mobile (GSM) communication networks and made available to the treating physician after analysis.[38] With increasing use of these devices comes a rising demand on cardiac services for device surveillance. Improvements in the technology have made RM a viable route to improving patient safety while also enhancing service delivery. RM enables faster clinical response times when abnormalities are detected,[39] and also enables the patient to be a more active participant in their own care. Automated device status checks ensures enhanced safety and frees up clinical time as unnecessary clinic visits can be avoided.

Although several of the novel monitoring devices and systems described above have demonstrated potential to monitor AF and related arrhythmias, most require further study to demonstrate safety and efficacy in real-world application. However, they provide a glimpse of future possibilities, where mobility for patients will not be impaired by their health-monitoring devices, where they can receive immediate information about their current clinical status and where the burden on cardiac services can be reduced through early detection and intervention in a wide clinical application and at relatively low cost.

Mobile Health in MI

MI remains a leading cause of morbidity and mortality worldwide.[40] Through the application of evidence-based therapies, post-MI survival rates have improved and led to an increase in the population of survivors at risk of a subsequent event and who are therefore candidates for secondary prevention.[41] Most mobile health studies related to MI have looked at acute, prehospital ST-elevation MI (STEMI) care and demonstrated significant improvements in outcomes.

Early reperfusion improves outcomes following STEMI and many initiatives have focused on reducing time-to-treatment or door-to-balloon time (DBT).[42] In-hospital STEMI care systems have been successfully and widely implemented, and small improvements are unlikely to bring further significant benefit.[42] The prehospital STEMI care system now holds the main opportunity for reducing total ischemic time and time-to-treatment and hence for improving outcomes.[42] In their review, Al-Zaiti et al.[43] found prehospital diagnosis of STEMI via ECG can potentially shorten DBT, decrease infarct size, limit reduction in ejection fraction, improve specialized care access, reduce hospital length of stay (LOS), reduce unnecessary referrals and costs and, in asymptomatic middle-age adults, improve risk stratification. Several telehealth initiatives have trialled prehospital ECG transmission using mobile technologies and similarly found reduced DBT.[44] Brunetti et al.[45] found mobile-transmitted ECGs by EMS improved rates of immediately diagnosed MI, importantly including for atypical presentation, in a large elderly population accessing emergency services, resulting in reduced time to treatment. Recent advances in technology have also enabled accurate interpretation of prehospital ECGs by cardiologists on smartphones in real time,[46] thereby enabling appropriately triaged MI transfers directly to percutaneous coronary intervention (PCI) centers and significantly decreasing DBT.[47] The STAT-MI trial[48] used a fully automated wireless network for communicating automatic 12-lead ECGs to offsite cardiologists' smartphones, which facilitated direct triage of STEMI patients to a cardiac catheterization laboratory. They found patients had shorter DBT, significantly lower peak troponin and creatine phosphokinase, higher left ventricular ejection fractions and shorter hospital LOS compared with control patients. Automated systems such as STAT-MI can go some way to addressing transport delays and inconvenience to EMS caused by ECG transmission issues.[43] Integrating EMR access and historical ECG details to support ECG interpretation on cardiologists' smartphones[43] can also improve diagnostic accuracy and help resolve potential high false-positive rates of activating PCI laboratories unnecessarily.

There is extensive evidence that secondary prevention programs to reduce CVD risk factors can improve CVD morbidity and mortality in MI survivors,[41,49–50] with even modest treatment effects providing cost-effective benefits. CR as a recommended approach to secondary prevention is not limited to patients with recent MI or acute coronary syndrome – it is also indicated for those with chronic stable angina, HF and following coronary artery bypass surgery, PCI, valve surgery or cardiac transplantation.[51] Although these programs are traditionally delivered from a hospital outpatient exercise clinic, cost and access constraints have necessitated the development of alternative home-care CR models and the utilization of telemonitoring.[41] Mobile devices offer new opportunities for delivering CR through SMS messaging, journaling apps, connected measurement devices, coaching and continuous and RM and supervision of patients.[9]

The Care Assessment Platform (CAP) is a CR model that uses a journaling app on patients' smartphones to collect health-related information (e.g., physical activity, food intake, weight, BP, stress and amount of sleep), which is then graphically displayed to both the patient and their CR coordinator to monitor the patient's achievements against individually set CR goals over time.[3] Early findings of this study have been reported to show significantly improved CR completions rates.[52] New innovations like HeartCycle's guided exercise (GEX) system,[53] where patients wear a shirt with embedded sensors that can live-stream health parameters (e.g., ECG, heart rate [HR], breathing rate and activity) via a mobile device, will further support exercise-based CR, independent of location.

Extending the study of the use of mobile technologies to other types of MIs and wider care settings is likely to highlight many new opportunities for improving patient outcomes and service delivery. CR seems a likely candidate for significantly benefiting from the use of these technologies, and publications of outcomes from RCTs evaluating its utilization are eagerly anticipated.

Mobile Health in HF

HF is a life-threatening progressive disease and is often associated with dramatically diminished quality of life (QoL) and high levels of comorbidity.[54] It places a huge economic burden on the healthcare system, especially due to high rehospitalization rates.[55]

Although some arrhythmia detecting and monitoring initiatives discussed above could apply to HF, the majority of HF mobile health studies have focused on the long-term management of nonpharmacological (e.g., fluid and dietary sodium restriction, physical activity and weight gain) and pharmacological therapies that could be delivered in patients' homes. This focus has been driven by poor adherence to self-care, with previous studies showing that the least frequently performed self-care behaviors include daily weighing, restricting fluid intake, informing the care team of HF-related symptoms and recognizing weight gain.[56]

A few studies have explored the feasibility of portable home-monitoring devices wirelessly connected to a smartphone to monitor HF patients[57–59] and demonstrated high transmitted ECG diagnostic quality and integrity of BP and bodyweight measurements. Another study validated remote echocardiographic interpretation on a website-enabled smartphone utilizing software designed for this purpose against workstation reading by expert echocardiographers, demonstrating minimal loss of diagnostic accuracy when using the smartphone.[60]

Piotrowicz et al.[59] demonstrated that home-based telemonitored CR in HF was safe, even when patients felt unwell and had episodes of AF, through monitoring ECG fragments recorded automatically on a telemonitoring device during CR and transmitted to a monitoring center via a mobile phone.

Weight monitoring is particularly important for patients with HF, as rapid weight gain is strongly associated with hospital admission[61] and high mortality.[62] Daily weight monitoring is a key recommendation for self-management of congestive heart failure in major guidelines.[63–65]

Despite these recommendations, a review found that only approximately 40% of patients regularly monitored their bodyweight, and approximately a third of patients did not take any action when they gained weight.[66] To address this issue, a major component of mobile health-enabled HF care programs is to assist patients in adhering to weight management.

Seto and colleagues[67] tested a rule-based clinical decision-support system aimed at improved self-care and clinical management that generated alerts and instructions based on patients' weight, BP, HR and symptoms. Over the 6-–month RCT, 1620 alerts were generated in 50 HF patients, leading to various clinical interventions, including 105 medication interventions. Findings indicated that using the HF rule set improved patients' QoL and self-care. Although their trial was underpowered to detect differences in hospitalization, mortality and ED visits between groups, the telemonitoring group had high levels of adherence to daily weighing (70% completed at least 80% of possible daily readings) and showed significant improvements in QoL and self-care maintenance compared with the control group. Another recent study used weight monitoring from a wireless weight scale, transmitted to a mobile phone, combined with an algorithm to improve sensitivity in predicting clinical deterioration in 87 HF patients.[68] The HeartPhone algorithm, based on alerts generated from moving averages of daily weight data deviations above the norm for each individual patient, predicted HF events with significantly more sensitivity than guideline weight change methods. The TEMA-HF 1 RCT[69] evaluated the impact of intensive management of 160 HF patients through a telemonitoring-facilitated collaboration between general practitioners (GPs) and a HF clinic. The intervention group used electronic devices that automatically transmitted daily weight, BP and HR data via mobile phones to a database. Automated alerts to the GP and HF clinic were generated when predefined limits were exceeded to initiate clinical interventions. They found significantly lower all-cause mortality and reduced number of days lost to hospitalization, death or dialysis in the telemonitored HF patients compared with usual care.

However, not all mobile-enabled telemonitoring studies have confirmed these improved outcomes in terms of hospitalization rates, morbidity and mortality. Koehler et al.[70] found that RM had no significant effect on HF hospitalization, cardiovascular death or all-cause mortality in 710 stable HF patients, despite good compliance with daily data transfers, compared with usual care. Further subgroup analyses[71] showed improved outcomes in specific HF patient groups, but further studies are required to identify those who stand to benefit most. Although meta-analyses[72,73] of HF telemonitoring systems have been performed to overcome underpowered RCT studies, their observations have not evaluated the effect of the mobile health components on outcomes of hospitalization, morbidity and mortality. On the other hand, approaches in HF telemedical management and mobile health are based primarily on ongoing monitoring and early detection of clinical deterioration, with corresponding timely interventions, in which case the focus on keeping HF patients maintained and out of hospital is justified.