Cardiovascular (CV) disease is the leading cause of morbidity and mortality in Portugal, which highlights the impact of atherosclerosis on public health and the need to implement primary and secondary prevention measures.1 Cardiac rehabilitation programs (CRPs) were established to promote early recovery after an acute event and were designed to fully reintegrate patients into society. Their aims are to inform patients about their condition and to educate them on ways to prevent recurrence by controlling CV risk factors and prescribing physical exercise based on CV risk stratification in order to improve their functional capacity and quality of life.2

The last 10 years have seen growing evidence of the benefits of CRPs in coronary artery disease (CAD), with mortality reduced by 20–30% compared to patients not undergoing cardiac rehabilitation.3–7 Despite these proven benefits, data from a 2007 survey by the European Association of Cardiovascular Prevention and Rehabilitation show that Portugal, together with Spain and Eastern European countries, enroll less than 5% of eligible candidates on such programs, compared to the European average of 30%.3

There are few studies assessing the long-term effects of CRPs in terms of maintaining the preventive measures instituted in their initial phase, especially with regard to the situation in Portugal.

The Cardiovascular Prevention and Rehabilitation Unit (CVPRU) of Centro Hospitalar do Porto – Hospital de Santo António is coordinated by a physiatrist and a cardiologist, and also includes specialists in vascular surgery, urology, psychiatry and endocrinology, as well as physiotherapists, nutritionists and nurses. The CRPs at the CVPRU consist of three distinct, consecutive phases, as recommended in international guidelines.8 Patients are referred to a CRP from cardiology outpatient clinics or during hospitalization in cardiology wards.

Phase I, begun in the hospital, includes the patient's medical history, investigation of comorbidities and education of patients and their carers concerning their condition and CV risk factors; patients are also encouraged to return to activity, under supervision, as soon as possible.

Phase II begins 2–3 weeks after hospital discharge, with assessment by the specialist in physical medicine and rehabilitation in the CVPRU. The educational process continues and an overall clinical evaluation is performed that includes the patient's medical history and cardiorespiratory, neurological and musculoskeletal exams, as well as functional assessment. Diagnostic exams are then scheduled (exercise testing and laboratory tests) for stratification of CV risk, on which an exercise program is based according to the current guidelines.9 Patients are also referred for other consultations at the CVPRU depending on clinical indications, such as nutrition, psychiatry, smoking cessation, urology and vascular surgery. This stage usually lasts 8 weeks but can vary between 6 and 12 weeks depending on clinical needs and the patient's response to exercise. It consists of weekly educational sessions on subjects related to CV risk factors and disease, and therapeutic exercise sessions. The latter are held twice weekly under the supervision of the physiatrist and cardiologist, in accordance with international guidelines on the level of supervision and monitoring appropriate to each case.9 In addition, patients are advised to exercise during the rest of the week, based on the general principles of the program, and are encouraged to increase their level of activity in a safe manner. Each session lasts between 60 and 90minutes; the exercise protocol includes a warm-up period, aerobic training (treadmill and arm and leg ergometers), strength training (using dumbbells, exercise balls and other strength training equipment), a cool-down period and flexibility exercises. The intensity of each exercise component is determined for each individual patient based on their exercise heart rate calculated by the Karvonen formula9 using the data obtained from exercise testing; this is complemented by the patient's rating of perceived exertion on the Borg scale.9 Each session includes a brief clinical assessment, including a questionnaire on relevant symptoms and compliance with medical therapy. Any change in drug therapy, including optimization of dosage when indicated, is the responsibility of the CVPRU's cardiologist in consultation with the attending cardiologist.

During phase III (follow-up), the patient is assessed and encouraged to maintain exercise, healthy behaviors and compliance with prescribed therapy. Follow-up is by outpatient consultations in the physical medicine and rehabilitation clinic, with laboratory tests and functional reassessment through exercise testing at 6 and 12 months after the beginning of phase II, which serves as the basis for a review of the training components prescribed, particularly their intensity, adjusted on the basis of the exercise heart rate whenever necessary.

The present study aims to assess the effects of a CRP in CAD patients over a 12-month follow-up period with regard to control of CV risk factors.

Of a total of 329 patients, 73 were lost to follow-up. The study population thus included 256 patients, most of whom (81.6%) were referred for CRP during hospitalization in the cardiology ward. The majority were men (76.2%), and mean age was 61.1±10.6 years (30–83). The most common admission diagnosis (65.3%) was acute coronary syndrome (ACS) (Table 1).

The prevalence and changes in CV risk factors over the study period are presented in Tables 2–4.

The main aim of this study was to assess the long-term effects of an exercise-based CRP in CAD patients with regard to the modifiable CV risk factors of obesity, waist circumference, hypertension, dyslipidemia, diabetes, smoking and sedentary lifestyle.

A high proportion of our study population had dyslipidemia at admission (74.2%), which is in agreement with the literature.12,13 The relationship between TC, LDL-C and HDL-C levels and atherosclerosis is based on solid evidence. Triglycerides are also linked to greater risk of CAD, although their role in atherosclerotic CV disease is less well established.8,14 The risk associated with hypercholesterolemia is progressive and reducing TC by 10% lowers the incidence of CAD by 25% at five years.11 At the end of phase II of the CRP (3 months), the mean reduction in TC was over 10% and hence a significant reduction in CV risk can be assumed. However, there are conflicting results in the literature on the long-term effects of CRPs on lipid profile; some studies report that the benefits are not statistically significant in the long term,13 while others are in agreement with our results, with statistically significant benefits being maintained.12 Among the explanations that have been put forward for successful outcomes is the fact that some programs include nutritional support and educational sessions, leading to more consistent benefits. Both components were included in our CRP.

The prevalence of obesity is so high worldwide that the World Health Organization (WHO) considers it to be the global epidemic of the 21st century. The latest data for Portugal15 indicate a prevalence of overweight and obesity of 53.6%. The study population presented an even higher prevalence, reflecting their greater risk. Our results are in agreement with other studies that have also found a high rate of overweight and obesity in CAD patients.13

Various studies have shown that obesity alone increases CV mortality16 and that a 5% reduction in body weight reduces CV risk factors, while a 10% reduction has significant effects on lipid profile, hypertension control, insulin resistance and coagulation profile.17,18

It is now recognized that body fat, particularly visceral fat, is a metabolically active organ that synthesizes and releases into the bloodstream a variety of compounds that play an important role in cardiovascular hemostasis.19 In Portugal, most women have WC >88cm, while the proportion of men at similar risk is considerably lower (38% have WC >102cm).20 The data from our study follow the same pattern of a predominance of women with high WC.

At the end of phase II of the program, there had been a statistically significant reduction in weight-related parameters. Similar results are found in the literature,21,22 which confirms the efficacy of these programs in reducing risk factors, although the benefits obtained were significantly less at 6 and 12 months. Some studies have reported no statistically significant improvement in these parameters in the long term13; one possible reason is the absence of specific weight-loss components in CRPs.21,22 Our program included dietary advice by a nutritionist for all patients but no specific measures were adopted for obese patients in the exercise component.

As in most countries, hypertension is a major public health issue in Portugal, given its high prevalence (42%), low treatment rate (39%) and low percentage of controlled patients (11%).11

In our patient population, 62.5% had hypertension as a CV risk factor and on initial assessment 25.8% had high BP. Thus, most patients had controlled BP at the start of the CRP, which may be explained by the fact that most were under optimized antihypertensive therapy, having been referred following hospitalization in the cardiology department.

There is strong evidence of the clinical benefits of BP lowering in hypertensive patients,8,11 and the benefits of exercise-based CRPs in BP control are well established.23–25 The CRP had a positive impact in reducing hypertension throughout the study period, which was statistically significant at all assessments, and at 12 months only 7.8% had uncontrolled hypertension.

The WHO estimates that 300 million people worldwide will suffer from diabetes by 2025. In Portugal, 6.5% of the adult population has diabetes (over 300000 individuals), and this figure is undoubtedly an underestimate, since it does not include undiagnosed individuals.11 Diabetes is a well-established risk factor for CV disease; although diabetic patients are likely to have other conventional CV risk factors such as hypertension and dyslipidemia, the 3-5-fold increase in CV risk associated with diabetes appears to be independent of other risk factors.11

At the start of the study, 34.4% of patients had a history of diabetes, which was poorly controlled in over half (HbA1C >6.5%). This figure is well above that published for Portugal, which could reflect a higher prevalence of this risk factor in CAD patients or underdiagnosis of the disease in the general population. The benefits of exercise and CRPs on blood glucose levels are well documented in the literature26,27 and our study showed a reduction in almost half of the patients with poor glycemic control.

Smoking is the main factor in reduced life expectancy and is responsible for over 50% of avoidable deaths, half of which are due to atherothrombotic disease. In Portugal, 19.6% of the population over the age of 10 are daily smokers.11 The link between active and passive smoking and risk of developing CAD, cerebrovascular disease or peripheral vascular disease is well established. The incidence of myocardial infarction is six times higher in women and three times higher in men who smoke 20 cigarettes a day than in those who have never smoked.11 The harmful effects are cumulative, in terms of both daily consumption and duration of the habit (exposure time). The INTERHEART study28 showed a strong correlation between the number of cigarettes and risk of ACS – five cigarettes a day increases the risk by 38%, while 40 a day increases it by 900% – and halving daily consumption also halves ACS risk. Smoking cessation is thus a priority in cardiac rehabilitation, and is even more important in the presence of atherothrombotic disease and in patients undergoing invasive procedures such as coronary bypass surgery, angioplasty or vascular surgery.19 CRPs therefore represent an excellent opportunity to stress the importance of smoking cessation.

In our study, the percentage of smokers had fallen by more than half at the end of follow-up. These results are in agreement with other studies showing higher rates of smoking cessation among individuals participating in CRPs.29

Exercise is crucial for primary, secondary and tertiary prevention of most of the common chronic and/or degenerative diseases found in contemporary societies, especially those with western lifestyles, particularly with regard to the causes and consequences of atherosclerosis.11 In 1997, Portugal had the highest prevalence of sedentary lifestyles (87.8%) of 15 European Union countries.30

The number of sedentary patients fell dramatically over the course of our study and at 12-month follow-up, only 9.8% maintained a sedentary lifestyle; levels of weekly physical activity increased by 174%. These results are a further illustration of the importance of CRPs in these patients.

On assessment at the end of phase II, a considerable and statistically significant improvement was seen in all CV risk factors, which is in agreement with the results reported in the literature31–35 that show consistent benefits in these patients from exercise-based CRPs.

There was an overall improvement in the parameters related to control of CV risk factors, which remained statistically significant throughout the 12 months of follow-up, albeit with some reduction in the benefits obtained. This reduction was mainly seen at the 6-month assessment, which may be due to a waning of the initial level of motivation associated with the acute event. The relative improvement observed at 12 months may have resulted from the reinforcement of healthy behaviors and preventive measures (particularly in terms of diet and exercise) that took place at the 6-month assessment in view of the worsening of parameters compared to the favorable changes seen at the end of phase II.

The difficulty in maintaining such benefits is particularly evident in anthropometric data, since BMI was the parameter that showed the least change, the improvement seen in the first 3 months being virtually cancelled out in subsequent assessments. These results are similar to other studies that have reported greater difficulty in maintaining statistically significant differences for these parameters.13 The main reason suggested, as pointed out above, is the lack of specific preventive measures when prescribing exercise for obese patients.

We feel the study is important in that it assesses the long-term effects of CRPs in a sizable patient population, including changes in CV risk factors. There are few works in the literature presenting similar research, and most assess risk factors over a shorter time period and analyze a narrower range of parameters. This is also the first study in Portugal reporting CRP results at 12 months in a population of this size.

The lack of a control group is a limitation of the study, but since studies comparing usual care versus cardiac rehabilitation have consistently demonstrated the benefits of CRPs,35 we are confident that our results can be attributed specifically to participation in a CRP.

CRPs are thus successful in treating patients with coronary disease, with benefits being maintained in subsequent months. Nevertheless, there is a reduction in these benefits once the hospital-supervised stage has ended, and it is therefore important to implement new strategies that will encourage patient compliance throughout the various phases of the program. It should be explained to patients that the benefits are often lost after phase II unless they adhere strictly to the preventive measures prescribed. Other interventions could be implemented, including a 3-monthly supervised exercise session accompanied by an educational component, in order to reinforce the basic concepts underlying prevention and health promotion, and monthly telephone calls and online communication to promote closer contact between the patient and the CRP team. It is also essential to make patients aware that they are responsible for their treatment and rehabilitation, since the latter will mainly depend on their own actions.

In our opinion, this study highlights the importance of these programs for secondary prevention of atherosclerotic disease and supports their applicability in clinical practice. There is thus a need to increase the referral rate to the CRPs currently available in Portugal and to establish new centers, in order to provide the care that is essential for full recovery after an acute event and for prevention of cardiovascular disease.

The authors have no conflicts of interest to declare.