The CROS meta-analysis2 evaluated the effectiveness of cardiac rehabilitation on total mortality and other clinical end points after an acute coronary event, but it considered only clinical studies performed during and after 1995. These strict criteria were chosen to evaluate the role of this intervention in the era of contemporary optimized treatment. The included studies involved mostly patients with stable coronary artery disease (158 781 patients), patients after an acute coronary syndrome (46 338 patients), and patients after a coronary artery bypass graft (14583 patients), and it involved 219 702 patients in total. CROS demonstrated that cardiac rehabilitation reduced total mortality in all populations, but not hospital readmissions and nonfatal cardiovascular events. However, the meta-analysis had several inherent limitations. In several studies, the information on cardiac rehabilitation protocols, content, and the processes used to form the groups was scarce, with different implemented exercise programs and very heterogeneous populations. Furthermore, the distribution and combination of secondary outcomes differed in every study, with a large variation in the statistical methods used. Therefore, it was not possible to perform any subgroup analyses.

Poffley et al published a systematic review on all available cardiac rehabilitation registries at both national and international levels3; it was based on a search of four databases conducted in July 2016. Finally, eleven articles were included that comprised seven national registries and one international registry (of twelve European countries). Data were most often provided to the registry by a web based application and the data collected included individual-level data, such as sociodemographic characteristics, medical history, and clinical measurements). This review showed that there was a large heterogeneity in the registries, mainly due to the differences in cardiac rehabilitation structure, legislation, funding, and national guidelines. Follow-up data were missing and the evaluation of cardiac rehabilitation outcomes limited.

EuroCaReD,4 a multinational cardiac rehabilitation registry in European countries, was created as a platform for putting together information on the clinical status of cardiac rehabilitation across Europe. Although EuroCaReD is one of the first international registries, its preliminary findings showed almost the same disappointing results (in terms of heterogeneity, reliability, and representativeness) as the rest of the registries presented by Poffley et al.

To overcome problems and challenges in developing cardiovascular disease registries in Europe, the creation of specific recommendations by scientific associations and countries, which have a long experience in maintaining cardiac rehabilitation registries, is an emerging need.

The interest of cardiac rehabilitation experts has been recently focused on frail patients. Frailty is a geriatric syndrome characterized by a vulnerability status associated with declining function in multiple physiological systems and the loss of physiological reserves. It correlates to medical outcomes in the elderly, and it has been shown to have prognostic value for patients in different clinical settings, such as in patients with coronary artery disease, patients after cardiac surgery or transvalvular aortic valve replacement, patients with chronic heart failure, or patients after implantation of a left ventricular assist device. The prevalence, clinical relevance, and prognostic relevance of frailty in a cardiac rehabilitation program have not yet been well characterized despite the increasing frequency of elderly patients in this setting, where frailty is likely to influence the onset, type, and intensity of the exercise training program as well as the design of tailored rehabilitation interventions6. Therefore, the need to start looking for frailty in elderly patients entering cardiac rehabilitation programs is emerging, as is the need to have a better understanding of whether exercise-based cardiac rehabilitation may change the course and prognosis of frailty in cardiovascular patients. 

The European guidelines have considered alternative modes of cardiac rehabilitation, such as home-based rehabilitation and telerehabilitation, ie, the use of electronic communication and information technologies to provide and support remote clinical care after an acute cardiovascular event., In a prospective evaluation, home-based cardiac rehabilitation was tested in frail patients awaiting an elective coronary artery bypass graft or valve surgery. No adverse events or cardiac symptoms were reported and there were significant improvements in the clinical frailty score, the 6-minute walking test distance, and the short physical performance battery total score. A large randomized controlled study is required to reveal the potential beneficial effects of home-based cardiac rehabilitation in this patient population.

In the last years, the implementation of mobile computing and communication technologies for health service and information (ie, mHealth) has increased patient engagement while reducing health care costs and improving patient outcomes. A major concern is that the development of mHealth has not been driven by the needs and expectations of healthcare professionals and patients, but mainly by the technical possibility of the devices. However, little is known about cardiac patients' interest in and use of mobile technology, particularly for health reasons, or about whether the usage of mobile technology varies across patient demographics.

A study was conducted to describe cardiac patients' use of mobile technology and determine variations between age groups after adjusting for education, employment, and confidence in using mobile technology. 10 Cardiac patients eligible for attending cardiac rehabilitation (mainly after percutaneous coronary intervention [33.3%, 94/282] and myocardial infarction [22.7%, 64/282]) were recruited from nine hospitals and community sites across metropolitan and rural settings in New South Wales, Australia. The participants showed an unexpectedly high interest and confidence with using mobile technology, willingness and interest in learning, and health-related use. The majority (91.1%) used at least one type of technology device, 70.9% used mobile technology (mobile phone/tablet), and 31.9% used all types. Technology was used by 54% for healthcare purposes, most often to access information on health conditions (41%) and medications (34.8%). Age, school education, and areas of living had an important independent association with the use of mobile technology after adjusting for education, employment, and confidence. The youngest group (<56 years) was over 4 times more likely to use any mobile technology, 5 times more likely to use mobile apps, and 3 times more likely to use technology for health-related reasons than those in the oldest group (>69 years). Participants who had completed high school were twice as likely to use mobile technology apps and mobile technology for health-related reasons as those who had not completed high school. 

Finding innovative and cost-effective care strategies that induce long-term health benefits in cardiac patients constitutes a big challenge today. The feasibility and effi- cacy of a 4-month integrated telerehabilitation home-based program (Telereab-HBP) was evaluated in 112 patients with combined heart failure and lung disease. Telereab- HBP included remote monitoring of cardiorespiratory parameters, weekly phone calls by the nurse, an exercise program, and weekly monitoring by the physiotherapist. After 4 months, the intervention group showed improvements in exercise capacity (A6-min walk test, +60), time free from hospitalization, dyspnea index, physical activity profile, disability (Barthel), and quality of life compared with the control group. At 6 months, these benefits, regarding outcomes, were maintained.

The aim of the Telerehab III follow-up study was to assess whether a 6-month cardiac telerehabilitation program could induce long-term health benefits and remain cost-effective after the teleintervention ended. In 126 cardiac patients, 2 years after completing a multicenter, randomized controlled telerehabilitation trial, exercise tolerance fell significantly in the intervention group at year 2 vs year 1 (24±8 mL/min*kg at year 1 vs 22±6 mL/min kg at year 2; P<0.001), but it remained significantly higher than the control group (P=0.032). Dividing the incremental cost (€878/patient) by the differential incremental quality-adjusted life years (0.22 quality-adjusted life years) yielded an incremental cost-effectiveness ratio of €3993/quality-adjusted life year, demonstrating cost-effectiveness up to 2 years after the end of the intervention.