Effectiveness of the innovative Austrian phase III cardiac rehabilitation model on cardiovascular risk factors: a nationwide registry

Abstract

Introduction

The Austrian model of outpatient cardiac rehabilitation (CR) begins right after discharge from the acute care hospital. During phase II (OUT-II), it provides a facility-based, professionally supervised, multidisciplinary programme of 6 weeks. The subsequent, supervised phase III (OUT-III) lasts 6 months. In 2017, a 3–6 months lasting unsupervised home-based training has been added, which is followed by a 4-week facility-based evaluation and training period, called ‘refresher’. We aimed to assess the effectiveness of this programme using a nationwide registry.

Methods

Anthropometric data, resting blood pressure, lipid profile, maximum exercise capacity (P_max), anxiety (HADS-A) and depression (HADS-D) of all patients (n=1458) who participated in OUT-III between 1 January 2018 and 30 August 2022 were analysed. Data were assessed at the beginning of OUT-III (OUT-III_start), end of the supervised period (OUT-III_end) and during the refresher (OUT-III_refresher).

Results

From OUT-III_start to OUT-III_end, P_max (155±1.4 W to 167±1.6 W; p<0.001) and high-density lipoprotein (HDL) increased (49±0.4 mg/dL to 51±0.4 mg/dL; p<0.001), low-density lipoprotein (LDL) decreased (82±1.0 mg/dL to 79±1.1 mg/dL; p<0.001), while total cholesterol (CHOL) remained statistically unchanged (150±43.3 mg/dL to 149±43 mg/dL; p<0.999). From OUT-III_end to OUT-III_refresher, P_max slightly decreased (164±1.6 W; p<0.001), HDL further increased (52±0.5 mg/dL; p<0.020), whereas LDL (79±1.3 mg/dL; p<0.999) and CHOL remained unchanged (149±41 mg/dL; p<0.999).

Anxiety (4.8±0.1 aU, 4.2±0.1 aU; p<0.001, 4.0±0.1 aU; p<0.001) and depression (3.7±0.1 aU, 34±0.1 aU; p<.001, 3.1±0.1 aU; p<0.001) continuously decreased from OUT-III_start to OUT-III_end and the OUT-III_refresher.

Conclusion

OUT-III CR resulted in sustained improvement in P_max, blood lipids, anxiety and depression.

Correspondence to Dr Bernhard Reich; [email protected]

WHAT IS ALREADY KNOWN ON THIS TOPIC

• Cardiac rehabilitation (CR) is a structured programme with an IA level of evidence to support patients with heart-related conditions to recover faster after cardiac events, surgeries or chronic heart disease. Although evidence shows that CR significantly reduces the risk of recurrent cardiovascular events, improves exercise capacity, quality of life, morbidity and mortality, sustainability of these programmes is often challenging. In Austria, this issue has been addressed by implementing an extended phase 3, which includes an unsupervised period of 12 weeks on average before patients are reassessed during an on-site refresher of 1 month. This study aimed to assess the effectiveness of this programme.

WHAT THIS STUDY ADDS

• Evaluation of this unique and newly implemented rehabilitation programme revealed the following beneficial effects: increased exercise capacity, increased high-density lipoprotein, decreased low-density lipoprotein as well as decreased anxiety and depression. Since during the 12-week home-based period, patients maintained the beneficial changes previously achieved, it can be concluded that our prolonged rehabilitation programme facilitated the transition from institutional to home-based lifelong lifestyle changes.

HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

• The Austrian CR model can serve as a template or at least inspiration for implementing or improving CR programmes in other countries. It demonstrates that and even how a phased approach can be integrated within a healthcare system. It also documents the effectiveness of long-term CR programmes in fostering sustainable lifestyle changes.

Introduction

Cardiac rehabilitation (CR) is a multidisciplinary therapeutic intervention aimed at maintaining or regaining long-term occupational and social integration. Medical societies rate CR class IA, the highest level of evidence.¹

The Austrian model of CR consists of four phases. Phase I refers to mobilisation and early rehabilitation in the acute care hospital. Phase II can follow right after discharge in an inpatient or outpatient setting and phase III relates to a continuation of phase II, however, with less frequent visits to the CR facility in order to taper of institutionalised CR.² Phase III aims to foster long-term healthy lifestyle habits, including home-based exercise (figure 1), by offering patients ongoing, but reduced support from a multidisciplinary team.

Figure 1. Illustration of the Austria Outpatient Cardiac Rehabilitation Model (2017-24). Upper row illustrates places of execution, namely the rehabilitation centre and/or patient’s home; the four tracks visualise exercise training, physical examination by a medical doctor, health literacy and personalisable modules assigned according to the patient’s needs. Tally list illustrates the number of sessions in each track per phase. Out-III start , OUT-III end and OUT-IIII refresher depict time points of measurement in this study.

This aims to improve adherence to lifestyle change in preparation for lifelong phase IV, which is one of the key challenges post-CR. Previous analyses of an Austrian nationwide registry demonstrated that the Austrian out-patient model is effective in improving cardiovascular risk factors including exercise capacity. Specifically, Reich et al² reported that cholesterol (CHOL) significantly improved (data are arithmetic mean and range) from 172 mg/dL (62–473) to 156 mg/dL (64–393), p<0.001; LDL from 98 mg/dL (17–335) to 84 mg/dL (6–263), p<0.001; triglyceride from 124 mg/dL (17–1020) to 117 mg/dL (7–1020), p<0.001; and exercise capacity from 130 W (20–330) to 150 W (30–373) equivalent to a 14% increase. Furthermore, a retrospective cohort study indicated lower mortality in OUT-III patients compared with control.^{3 4}

The model of CR investigated here was introduced in 2017, it continued to provide CR for up to 12 months just like its predecessor but was divided into two parts: part 1 now lasts six months and includes 60 sessions lasting 50 min, each of which 33 sessions consist of supervised exercise training, up to 12 of health literacy courses, and up to 5.5 of medical examinations including exercise testing at the beginning (OUT-III_start) and end (OUT-III_end) of part 1 (ie, OUT-III_start till OUT-III_end). The remaining 9.5 sessions can be used according to patients’ needs.

After OUT-III_end, patients are advised to conduct home-based and unsupervised exercise training for three to six months. The purpose of this part of phase III is to support patients in integrating training into their social environment and daily life, in order to foster sustainable, that is, lifelong lifestyle changes. Subsequently, patients are called in for part 2: a one month ‘refresher’ to the rehab centre, in order to assess the outcome of the home-based period and to support patients with additional 11 sessions including one medical examination and exercise testing (OUT-III_refresher) at the beginning of the ‘refresher’, at least three supervised exercise training sessions, and at least four educational, individual psychological and nutritional counselling sessions.

The novelty of this newly implemented system lies in (1) the shortening of OUT-III from 12 to six months, (2) the introduction of a subsequent home-based phase lasting three to six months and (3) a four-week refresher that follows thereafter.

This unique CR model, which could serve as a blueprint for other European countries, but has not yet been evaluated. Thus, the effectiveness of the Austrian phase III programme on cardiovascular risk factors, such as body mass, blood pressure, exercise capacity, blood variables including CHOL and its subfractions, remains unknown. Therefore, it was the aim of this study to evaluate the reorganised phase III of the Austrian model of CR in respect of these cardiovascular risk factors by aggregating patient-related data from seven outpatient Austrian rehabilitation facilities, representing a nationwide registry.

Methods

Study design

From 1 January 2018 till 30 August 2022, seven Austrian outpatient CR centres accredited by the Austrian Society for Prevention and Rehabilitation prospectively entered data of all patients assigned from the social security holder to OUT-III into our nationwide registry (N=1458). Data were collected at OUT-III_start, OUT-III_end and during OUT-III_refresher. Diagnoses that qualify for CR in Austria have been published elsewhere in greater detail and comprise among other acute coronary syndrome, percutaneous coronary intervention, stable coronary heart disease, aortocoronary bypass surgery, other surgeries of the heart or the big vessels, heart and lung transplantation, chronic heart failure, pulmonary hypertension, peripheral artery occlusive disease, prevention in motivated high-risk patients, electrophysiological intervention, implantation of a cardiac pacemaker or a defibrillator, haemodynamically stable arrhythmia, sustained ventricular tachycardia and cardiac arrest.⁵

Data acquisition

At all timepoints (OUT-III_start, OUT-III_end, OUT-III_refresher) patients underwent assessment of body height and mass. Body mass index was calculated according to the formula of Keys.⁶

Venous blood samples were drawn after a 10 hours overnight fast. Participants were prompted to refrain from exercise training at least 16 hours before blood drawing. Blood samples were analysed at certified laboratories for total CHOL, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides and glucose.

Patients performed incremental cycle ergometer tests until volitional exhaustion or until criteria for termination were reached.^{7 8} Test protocols were in accordance with the Austrian guidelines for ergometer testing⁷ and were kept identical for each patient during all tests. During ergometer testing, cardiac activity was continuously monitored by a 12-lead ECG. Blood pressure was measured manually at rest and immediately before each increment.

Psychological assessments were performed with the ‘Hospital Anxiety and Depression Scale’ (HADS)⁹ questionnaire. Work-related medical issues were assessed with the Screening Instrument for Identification of a Demand for Medical-Vocational Oriented Rehabilitation—Chronic Diseases (SIMBO-C) questionnaire, an instrument to identify patients with chronic diseases and resulting extensive work–health-related problems.¹⁰

Finally, physicians defined individual rehabilitation goals together with the patient. At OUT-III_refresher, both evaluated the individual goals and rated if these had been reached, partly reached or not been reached using the Goal Attendance Score—GAS.

Exercise training

An exercise scientist specialised in medical exercise therapy or a physiotherapist supervised all training sessions. During each endurance training session, a physician was present at the institute. Endurance and strength training sessions were carried out during every visit and lasted up to 50 min each.

Endurance training consisted of continuous cycle ergometer training at 60%–70% of heart rate reserve (HRR; that is, peak heart rate minus resting heart rate)¹¹ or high-intensity interval training of up to 85%–95% HRR, depending on the patient’s fitness and health status. Warm-up and cool-down were performed at 50% HRR. During endurance training sessions, heart rate was monitored using a three-lead ECG or electric heart rate chest belt and monitor. In addition, patients were asked to perform home-based endurance training on at least two more days per week.

Strength training protocols focused on major muscle groups of the upper and lower body. For each exercise, the weights were selected so that a maximum of 15 repetitions resulted in local muscular exhaustion. The initial training session was used to determine individual weight for each exercise. During training sessions, the supervising staff increased the weight whenever patients were able to execute more than the targeted 15 repetitions.⁵

During both the supervised and unsupervised part of phase III patients were asked to be as active as possible and to meet the recommended physical activity of 75–150 min of vigorous or 150–300 min of moderate intensity plus two strength training sessions per week.¹² Patients were asked to document training sessions and barriers that eventually hindered them to meet these recommendations.

Statistical analysis

We applied the mixed model procedure in SPSS (SPSS V.27, Chicago, Illinois) to calculate differences between time points while accounting for repeated testing and different sample sizes at OUT-III_start, OUT-III_end and OUT-III_refresher. ‘Timepoint’ was used as a fixed effect and ‘subject’ was added to the selected heterogeneous first-order autoregressive covariance structure. P values for main effects were calculated within the model, and in case of significant main effects, pairwise post hoc testing was performed via Bonferroni tests. Level of significance was set to p≤0.05.

Data are presented as arithmetic mean and SE or SD. Differences between OUT-III_start, OUT-III_end and OUT-III_refresher are presented as absolute or relative values.

Ethics and dissemination

All subjects provided written informed consent before study inclusion. The results will be disseminated through a publication. Data will be shared for suitable collaboration projects, if requested. Patient and public involvement is not applicable.

Results

Data of 1458 patients were analysed (average age: 60.0±11.9 years; average age of men (n=1174, 80.5%) was 56.2±9.2 years and of women (n=284, 19.5%) was 56.0±10.4 years). 77.5% of all participants completed the supervised part of OUT-III and 62.1% the refresher. Two patients died at home from unknown causes during the observation period. Occupational status, educational level and smoking status are presented in table 1, diagnoses are presented in table 2.

Table 1

Occupational status, education level and smoking status

Occupation/education/smoking	% of patients
Employed	70.7
Sick leave	5.3
Job seeking	5.1
Pension	17.2
Other occupations	1.5
Compulsory education	8.7
Apprenticeship	24.9
Skilled worker	26.1
High school diploma	10.2
University degree	10.4
Non-smoker	37.5
Ex-smoker	43.1
Smoker	10.0
Unclassified	9.3

Table 2

Patients’ main diagnosis

Diagnosis	ICD	%
Ischaemic heart disease (IHD)	I20-25	69.2%
Other forms of heart diseases	I30-I52	11.7%
Presence of cardiac and vascular implants grafts including heart transplant status	Z94.1 and Z95	8.6%
Other diseases		4.0%
Unclassified		6.4%

ICD, International Classification of Diseases.

Baseline data

Baseline data for exercise capacity, resting blood pressure and blood markers at OUT-III_start are given in table 3 and table 4.

Table 3

Exercise capacity, body mass, BMI, blood pressure and blood markers

	OUT-IIIstart	OUT-IIIend	OUT-IIIrefresher	Tfix	OUT-IIIstart vs OUT-IIIend	OUT-IIIend vs OUT-IIIrefresher	OUT-IIIstart vs OUT-IIIrefresher
Pmax, W	155±1.4 (152–158) (1361)	167±1.6 (163–170) (1174)	164±1.6 (161–167) (902)	<0.001	<0.001	<0.001	<0.001
Pmax/kg, W/kg	1.82±0.02 (1.78–1.85) (1360)	1.95±0.02 (1.92–1.99) (1126)	1.98±0.02 (1.88–1.96) (869)	<0.001	<0.001	<0.001	<0.001
Body mass, kg	87.0±0.4 (86.1–87.9) (1423)	87.3±0.5 (86.4–88.2) (1138)	87.6±0.5 (86.7–88.5) (873)	<0.001	0.01	<0.001	0.06
BMI, kg.m2	28.3±0.1 (28.0–28.6) (1358)	28.4±0.1 (28.1–28.6) (988)	28.5±0.1 (28.2–28.8) (803)	<0.001	0.03	<0.001	0.005
RRsys, mm Hg	120±0.5 (119–121) (1357)	120±0.5 (119–121) (1176)	120±0.6 (120–122) (905)	0.400	0.999	0.999	0.529
RRdia, mm Hg	78±0.3 (77–78) (1358)	77±0.3 (77–78) (1176)	78±0.3 (77–78) (902)	0.440	0.999	0.999	0.833
CHOL, mg/dL	150±1.3 (147–152) (1118)	149±1.4 (146–152) (775)	149±1.5 (146–152) (574)	0.833	0.999	0.999	0.999
HDL, mg/dL	49±0.4 (48–50) (1330)	51±0.4 (50–52) (987)	52±0.5 (51–53) (779)	<0.001	<0.001	<0.001	0.020
LDL, mg/dL	83±1.0 (81–84) (1347)	79±1.1 (77–81) (994)	79±1.3 (76–82) (777)	0.001	<0.001	0.999	0.022

Numbers in square brackets represent 95% CI; italic numbers in round brackets represent sample size.

BMI, body mass index; CHOL, cholesterol; HDL, high-density lipoprotein; LDL, low-density lipoprotein; P_max, maximum exercise capacity; P_max/kg, maximal exercise capacity per kg body mass; RR_dia, diastolic blood pressure; RR_sys, systolic blood pressure.

Table 4

Relative numbers of patients at given values for blood pressure and blood markers at the beginning of OUT-III_start

RRsys (mm Hg)	≤120	120–139	>140	Not reported
(%)	52	30.5	10.6	6.9
RRdia (mm Hg)	≤80	81–89	>90
(%)	61.7	18.1	13.4	6.9
LDL (mg/dL)	≤50	50–114	>115
%	14.9	61.5	16	7.6
HDL (mg/dL)	≥45
%	52.2			10.8
GLU (mg/dL)	≤110
%	61.9			10.6
TG (mg/dL)	≤150
%	67.8			8.7

Results for the Goal Attendance Score are given in table 5.

TG triglyceride GLU, fasted blood glucose; HDL, high-density lipoprotein; LDL, low-density lipoprotein; RR_dia, diastolic blood pressure; RR_sys, systolic blood pressure.

Table 5

Goal Attendance Score (GAS)

GAS	OUT-IIIend regularly	OUT-IIIend premature	OUT-IIIrefresher
Reached	36.4%	4.9%	56.5%
Partly reached	18.1%	7.9%	17.4%
Not reached	1.7%	18.3%	1.7%
Not available	43.9%	69.2%	24.5%

Changes in anxiety and depression

At OUT-III_start, OUT-III_end and OUT-III_refresher HADS-A was 4.8±0.1 aU, 4.2±0.1 aU (p<0.001) and 4.0±0.1 aU (p<0.001), while HADS-D was 3.7±0.1 aU, 3.4±0.1 aU (p<0.001) and 3.1±0.1 aU (p<0.001), respectively.

Discussion

We assessed the effectiveness of the Austrian-extended outpatient CR phase III programme released in 2017 by analysing prospectively entered data of a nationwide registry. The main results of the analysis are that an extended phase III programme induced significant and clinically meaningful improvements in exercise capacity within the first six months of supervised training and also beneficial changes in blood-borne cardiovascular risk factors as well as concomitant changes in depression and anxiety scores. During the subsequent three to six months unsupervised home-based CR, exercise capacity decreased slightly; however, several risk factors improved even further, indicating sustainable effects of this innovative outpatient CR model.

Supervised period of outpatient phase III (OUT-III_start–OUT-III_end)

Exercise capacity is the strongest prognostic marker for cardiovascular and all-cause mortality in both healthy populations and cardiac patients.^{13 14} Therefore, improving cardiovascular fitness during CR is of utmost importance.^{3 15 16} Our data indicate that exercise capacity significantly increased during the centre-based first part of OUT-III by approximately 12 W, which, in view of the test–retest reliability of 13 W, must be regarded as a true change.¹⁷ The efficacy of the intervention becomes particularly evident when considering that the level of exercise capacity at OUT-III_start was already elevated by approximately 20 W (14.3%) due to the physical training conducted in phase II CR.^{2 18} Hence, the six-month supervised training in OUT-III led to additional and meaningful improvement.

Also, CHOL and LDL are prominent risk factors, especially in patients with coronary artery disease.¹⁹ Our data show a significant decrease in LDL between OUT-III_start and OUT-III_end, while HDL increased, which is beneficial especially in patients with coronary artery disease.²⁰ Mean RR_sys and RR_dia remained within target range throughout OUT-III.

Since also anxiety and depression scores also improved, all risk factors either improved or remained within the specific target ranges during the supervised period from OUT-III_start to OUT-III_end.

Unsupervised period of outpatient phase III (OUT-III_end–OUT-III_refresher)

At OUT-III_refresher, that is, the end of the unsupervised phase of OUT-III, exercise capacity slightly decreased by 3 W. The extent of this change is marginal and clearly within the range of daily variability in cardiac patients¹⁷ and should therefore not be interpreted as a meaningful deterioration. Patients were thus able to maintain an exercise capacity, which was significantly above the level at OUT-III_start.

HDL and LDL significantly improved compared with OUT-III_start and improved even further relative to OUT-III_end. CHOL remained unchanged, as did blood pressure, both variables lying already within the normal range at OUT-III_start.

The vast majority (73.9%) of patients reported that they had fully or at least partly achieved their individual rehabilitation goals with the support of a professional, multidisciplinary team. Patients who demonstrate high levels of adherence to the rehabilitation programme appear to be more successful in achieving their goals. Conversely, those who discontinue participation in the rehabilitation programme are less likely to achieve their goals. However, it is at least theoretically possible that the latter group of patients cease involvement due to the rehabilitation programme or setting being unsuitable for them. This aligns with the recent calls for greater personalisation in rehabilitation in order to further enhance rehabilitation outcomes.²¹

In addition, further benefits of the refresher model became apparent. First of all, the refresher starts with a standard assessment of follow-up data that is embedded in clinical routine, thereby providing a highly standardised quality control of the CR. It also provides an opportunity to reiterate to patients the importance of adapting and maintaining a healthy lifestyle in a professional environment tailored to their individual medical history. Finally, the refresher allows to optimise individual training prescription, especially with regard to exercise intensity. Our data indicate that the refresher phase may be beneficial in terms of long-term sustainability, particularly with regard to maintaining exercise capacity. In addition, the follow-up after the home-based period allows for a structured re-evaluation of the individual patient and provides an opportunity for personalised recommendations. However, organising this phase poses practical challenges for both centres and patients. A potential solution may involve conducting medical assessments and exercise testing onsite, while shifting counselling and individual sessions to virtual formats such as telerehabilitation. This approach could reduce time demands and may help improve participation in the refresher phase and would save time for patients and centres and might increase patient participation in the refresher programme.

A majority of people and especially cardiac patients need to reduce sedentary time and to increase the volume of moderate to vigorous physical activity.²² Freene et al²³ demonstrated that a six-week phase II CR intervention resulted in an increase in low-intensity physical activity, which remained at a similar level until the end of a 12-month programme. In that study, also moderate-to-vigorous PA was increased 12 months after CR and sedentary time was decreased. However, WHO-recommended levels of PA were not achieved in that unsupervised setting, and sedentary time remained too high (11 hour/day). This indicates that supervised training is superior to unsupervised training for various reasons. These include the binding of training appointment agreements, the fact that participants are a social part of a rehabilitation training group, the extrinsic motivation experienced by participants through the rehabilitation staff to maintain or increase training intensity and the perception of safety while being supervised. The presence of experienced therapists with immediate access to medical support in the event of an emergency, along with the availability of access to medical or therapeutic experts in the event of questions, collectively provides patients with the necessary support to engage in regular training at moderate-to-vigorous intensities.

The training-mediated increase in exercise capacity, cardiovascular fitness and beneficial effects on risk factors achieved during the complete OUT-III are very likely to reduce the risk of CV and all-cause mortality.^{1 4 24} The results of this phase III CR programme initiated in 2017 are similar to our results of the previous phase III of the Austrian outpatient rehabilitation model that was applied until 31 December 2017.^{2 18}

Limitations

Our study has some limitations worth mentioning: medication reports were incomplete. Therefore, the individual effects of medication versus exercise training on cardiovascular risk factors cannot be assessed in full detail. Furthermore, not all patients agreed to participate in the refresher and those who did were free to participate anywhere between three and six months, thus resulting in relevant differences in duration of the home-based part. Furthermore, our dataset did not include information that would allow for an analysis of the reasons for these dropouts. Also, GAS was not reported by all participating centres. Finally, although all patients allocated to OUT-III by the social security authorities were included in the analysis, this registry is subject to unavoidable selection bias due to barriers in the healthcare system, which might prevent particular groups from accessing the CR scheme.

Conclusion

The Austrian model of extended, professionally supervised comprehensive phase III outpatient CR successfully supports patients in their attempt to sustain improvements in cardiovascular risk factors beyond phase II and to gain an additional improvement in exercise capacity that is maintained up to 12 months after the event or the first contact to rehabilitation. This makes the Austrian phase III model, attractive for other European countries, and we recommend that it can be discussed at the level of policymakers and healthcare providers.

Special thanks go to our patients who agreed to participate in this registry. Also, we owe thanks to the Austrian outpatient rehabilitation centres and their employees for their great work in collecting and entering data into our database and to the ÖGPR for its unremitting efforts for outpatient CR in Austria. We also thank Priv.-Doz. Dr. Wolfgang Hitzl, MSc, MSc for his statistical advice.

Data availability statement

Data may be obtained from a third party and are not publicly available. Data will be shared for suitable projects if requested.

Ethics statements

Patient consent for publication

Not applicable.

Ethics approval

This study involves human participants and was approved by Ethical Board of the Paracelsus Medical University, Salzburg, Austria Nr.: SS22-0029-0029. Participants gave informed consent to participate in the study before taking part.

Footnote

X @GunnarTreff, @Mayr

BR and GT contributed equally.

Contributors BR, GT and JN contributed to conception, KM, HO, AP, MP, HT, MW-D, SW, WZ, AK contributed to acquisition, GT and BR evaluated the data and drafted the manuscript. All authors critically revised the manuscript, gave final approval and agreed to be accountable for all aspects of work ensuring integrity and accuracy. JN is the guarantor.

Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests None declared.

Provenance and peer review Not commissioned; externally peer-reviewed.

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