1. Introduction
Cardiovascular disease (CVD) is becoming increasingly prevalent in sub-Saharan Africa due to an aging population and the emergence of cardiovascular risk factors [1] . With the introduction of cardiovascular rehabilitation (CR) in our cardiology departments in Senegal, more and more elderly patients are being referred for cardiac rehabilitation. According to the WHO, people aged 65 and over are considered elderly. Aging is a normal phenomenon, but it varies from person to person and organs do not age at the same rate in the same person [2] . As their functional reserves decline, the onset of an acute illness brings them closer to the point of decompensation. Elderly patients are often multi-pathological, not very autonomous or even dependent. Chronic pathologies increase with age, leading to over-medicalisation. This over-medicalisation is due to the sometimes large number of drugs prescribed in inappropriate doses and to the dysfunction of certain organs. Advanced age does not exempt patients from the need to correct their risk factors and receive therapeutic education. For patients who have difficulty retaining or understanding instructions, family support is invaluable whenever possible. CR has been shown to have a positive effect on the correction of cardiovascular risk factors, on the cardiovascular, respiratory and muscular systems, on exercise capacity and self-management, on quality of life and on patients' vital prognosis [3] . The incidence of myocardial infarction increases with age and the prognosis is often worse. Exercise involves multiple systems: the pulmonary, cardiovascular and muscular systems. By reducing the capacity of all the systems involved, ageing limits the ability to exercise [2] . Cardiac rehabilitation in the elderly must take into account all the parameters involved in exercise. The rehabilitation programme for able-bodied elderly patients is little different from that for younger patients. For those who are dependent, the main aim of the rehabilitation programme is to restore their autonomy, reintegrate them into society and enable them to learn to live with their pathology [2] . However, when a cardiac event occurs in the elderly, the disease is generally more severe, with more complications, and therapeutic interventions are more delicate to manage. Cardiovascular rehabilitation must also adapt to these specific conditions and, as in the case of younger patients, allow an increase in physical capacity and, above all, an improvement in psychological state and social autonomy. In fact, when it was first introduced into the therapeutic arsenal, rehabilitation was initially reserved for the younger population. With greater knowledge and mastery of the technique, the age range has widened to include the elderly, who present some specific aspects with regard to the indication and the rehabilitation technique itself [4] .
The lack of previous studies and the novelty of the discipline in Senegal are the reasons why we carried out this work.
The general objective of this study was to evaluate the results of cardiac rehabilitation on the autonomy and quality of life of elderly patients admitted to the different CR centres in Dakar.
2. Patients and Methods
This study was conducted at four cardiac rehabilitation units in Dakar: the Aristide Le Dantec Hospital (HALD), National Dalal Jamm Hospital, and the General Idrissa Pouye Hospital (HOGIP). These three units were established in 2021 and have a combined capacity of 40 patients per day. The Principal Hospital of Dakar (HPD), which opened in January 2019, has a capacity of 11 patients per day.
Ours cardiac rehabilitation are equipped with training rooms with bicycles, treadmills coupled with heart rate monitors, emergency kits and defibrillators. The team consists of cardiologists with diplomas in cardiovascular rehabilitation, nurses, physiotherapists and adapted physical fitness instructors.
This is a longitudinal, descriptive and comparative pre and post CR study conducted over a period of two (2) years.
We included in this study all patients over 65 years of age who were enrolled and followed up in the cardiac rehabilitation programme in the 4 units during the period from January 2019 to December 2021, and who completed at least 10 exercise retraining sessions.
We excluded from this study non-consenting patients and patients who started their cardiac rehabilitation programme but did not complete the required 10 sessions.
All patients who met the inclusion criteria were fully and consecutively recruited.
After an initial educational assessment, patients were enrolled in a cardiac rehabilitation programme consisting of three sessions per week for six to seven weeks. Exercise was performed either on a bicycle or on a treadmill, with endurance sessions always preceded by 3 - 5 minutes of warm-up and followed by 3 - 5 minutes of recovery.
All patients underwent a complete initial assessment, including a clinical examination and standard laboratory tests.
In addition to an ECG, a transthoracic echocardiogram, a stress test and a 6-minute walk test, a systolic pressure index (SPI) measurement, a quality of life assessment and a level of autonomy were performed.
In parallel with the training sessions, the patients take part in an educational programme (group sessions) on cardiovascular pathology and its treatment, dietary management with the aim of gaining acceptance for hygienic-dietary measures aimed at correcting cardiovascular risk factors, physical activity, help with smoking cessation and assistance with possible socio-professional reintegration.
Patients were re-evaluated three to six months following cardiac rehabilitation.
The exercise test was re-evaluated, either on a bicycle or a treadmill, to determine maximum HR (heart rate), training level and training HR within a range.
A 6-minute walk test was performed in patients with bicycle or treadmill limitations.
The Girerd questionnaire was used to assess compliance before and after rehabilitation. This questionnaire was developed in 2001 to assess compliance with hypertension treatment in specialised settings [5] and in 2004.
To assess autonomy before and after rehabilitation, we used the Katz index, which is a reference in the international literature [6] . Its aim is to objectively assess the level of autonomy in basic activities of daily living. It consists of six items with a binary score of 1 or 0, depending on whether the patient is independent or not in the corresponding activity. An older person with a score of less than 3 is considered to be highly dependent.
In addition to the activities of daily living described above, it was also necessary to consider other, more complex, daily activities involving cognitive functions, known as instrumental activities. In this context, the Lawton test is the reference in the international literature [7] . A maximum of eight instrumental activities are assessed (8 for women and 5 for men) and scored 1 or 0 depending on whether they are performed independently or not.
To assess quality of life before and after rehabilitation, we used the SF12 quality of life questionnaire, administered or self-administered by the patient. This is a generic questionnaire based on the MOS SF-36 developed by Ware and Sherbourne in 1992, which in turn was developed from the MOS and consists of 149 questions [8] .
Data were collected using a pre-designed form. They were entered using Sphinx software version 5.1.0.2. Data analysis was carried out using SPSS version 18.
In the descriptive study, frequencies and proportions were calculated for qualitative variables and means and standard deviations for quantitative variables.
The analytical study was carried out using comparison tables. To compare frequencies, we used the Wilxon test or the McNemar test for linked data, depending on the conditions of applicability, and to compare means, we used the Student's t-test for linked data, with a significance threshold of p < 0.05.
There was no risk to participants in this study. We obtained approval from the heads of the four hospital departments and then obtained informed consent from our patients. Data were anonymised.
3. Results
During our study period, 345 patients had received a complete CR programme in the four CR centres in Dakar, and 86 patients, or 24.92% of the population, were aged 65 years or older.
Our study was conducted on these 86 patients. The mean age was 70.35 ± 4.55 years for men and 69.27 ± 4.59 years for women, with extremes ranging from 65 to 84 years. The most common age groups were 65 to 70 years, followed by 70 to 80 years, with a clear male predominance. The male/female sex ratio was 4.73. The cardiovascular risk factors found in our population were male sex, followed by sedentary lifestyle and hypertension with frequencies of 82.55%, 74.41% and 65.11%, respectively.
Eighty-two patients (96.3%) had at least 2 cardiovascular risk factors. The mean cumulative cardiovascular risk factor was 3.28 ± 0.97.
In our sample, ischaemic heart disease was found in 73 patients (84.88%). Thirty-nine (39) patients (45.34%) had undergone angioplasty with active stent implantation and eight patients (9.30%) had undergone coronary artery bypass grafting. Other pathologies included congestive heart failure and lower limb obliterative arteriopathy.
Pre-rehabilitation comorbidities were dominated by joint pain, which was present in 17 patients (19.76%). Other comorbidities included asthma, glaucoma and cataract.
Initial evaluation revealed dyspnoea (NYHA stage II/III) in 35 patients (40.69%), followed by residual exertional angina in 21 patients (24.41%); the remainder of our cohort was asymptomatic.
The most common complication was arrhythmia, which occurred in 11 patients (12.79%). (Table 1)
During rehabilitation, the mean of exercise training sessions undertaken across the four centres was 19.02. Thirty-eight point seven percent (45%) of patients had accomplished over 20 exercise-training sessions.
Comparison of patient parameters before and after cardiac rehabilitation
Mean weight increased from 74.72 ± 11 kg to 74.41 ± 11.08 kg, waist circumference from 93.92 ± 7.74 cm to 92.46 ± 7.58 cm and BMI from 25.98 ± 2.56 to 24.99 ± 2.04 kg/m2. LDL cholesterol levels fell from an average of 1.10 ± 0.47 g/L to 0.83 ± 0.42 g/L. HDL cholesterol levels fell from a mean of 0.47 ± 0.13 g/L to 0.55 ± 0.13 g/L as shown in Table 2.
Functional capacity increased from a mean of 5.81 ± 2.38 Mets pre-CR to 8.68
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Table 1. Clinical characteristics of study population.
CCS: Chronic coronary syndrome; ACS ST+: Acute coronary syndrome ST+; AOMI: Obliterative arteriopathy of the lower limbs.
± 2.28 Mets post-CR (p < 0.001). as shown in Figure 1.
The 6-minute walk test was performed in 12 patients (13.95%) pre-CR and in 4 patients (4.65%) post-CR.
The mean values increased from 330.42 ± 170.50 in pre-CR to 524 ± 98.54 in post-CR (p = 0.119). Joint pain present in 17 patients before rehabilitation was present in 5 patients after rehabilitation (p < 0.001). Dyspnoea (NYHA stage II), present in 35 patients at baseline was present in 10 patients (11.62%) at final assessment. At the end, 88.37% of the patients in our group did not experience symptoms after completing CR.
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Table 2. Distribution of patients according to clinical parameters before and after CR.
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Figure 1. Distribution of patients according to functional capacity before and after re-training sessions (n = 86).
Re-hospitalisation after the CR programme was observed in 3 patients (3.48%). The reasons for this were acute pulmonary oedema, cardiac decompensation due one case of decompensation and due to Covid 19 infection.
The Girerd questionnaire was used to assess compliance. In our sample, we found good compliance with treatment at the final assessment. with a percentage of 96.80% compared to 53.6% at the initial assessment (p < 0.001).
Assessment of autonomy before and after CR
The Lowton and Katz indices were used to assess the autonomy of the elderly subjects before and after CR. According to the Katz index, the dependency rate decreased from 37.2% before CR to 20.9% after CR (p < 0.001).
According to the Lowton index, our dependency rate decreased from 44.18% pre-CR to 36.04% post-CR (p = 0.0156). Figure 2(a) and Figure 2(b) show the distribution of patients according to the Lowton and Katz indices before and after CR.
Before the CR programme, 10 patients (11.7%) “never” reported any discomfort in their social life as a result of their physical or emotional state of health, and 42 patients (48.8%) “never” reported any discomfort in their social life at the end of the CR programme.
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Figure 2. Distribution of patients according to Katz (a) and Lowton (b) index pre- and post-CR (n = 86).
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Table 3. Summary table of physical and mental quality of life score.
The physical quality of life score (PCS-12) increased from a mean of 41.61 ± 10.69 before CR to 61.30 ± 7.78 after CR (p < 0.001). The mental quality of life score (MCS-12) increased from a mean of 42.15 ± 10.27 pre-CR to 52.94 ± 10.86 post-CR (p < 0.001). Table 3 summarises the assessment of physical and mental quality of life using the SF12 questionnaire.
4. Discussion
The main objective of our study was to evaluate the results of cardiac rehabilitation on the autonomy and quality of life of elderly patients admitted to the different RC centres in Dakar.
During the period of our study, 345 patients benefited from a complete cardiac rehabilitation programme and 86 patients, i.e. 24.92% of the population, were at least 65 years old.
Our findings indicate a significantly lower participation rate among elderly subjects in CR programmes compared to the 50% rate reported by Khadanga et al. [9] . In this study, this low rate could be explained by the difficulty of access to transport to the RC centres in Dakar for this age group of patients and the lack of health insurance.
The mean age was 70.35 ± 4.55 years for men and 69.27 ± 4.59 years for women, ranging from 65 to 84 years. The most common age groups were 65 to 70 years, followed by 70 to 80 years, with a clear male predominance.
Kinic et al., in a comparable Nancy-based study, reported an older population [10] . The truth is, the Senegalese population is comparatively younger and life expectancy is lower in contrast to Europe.
In our sample, we found a male predominance with 71 men compared to 15 women and a sex ratio of M/F = 4.73. The low representation of women in rehabilitation has been reported in many other studies, but in different proportions [11] . Pavy et al., in their study of cardiac rehabilitation in coronary patients, found a male predominance of 93% compared with 7% [12] . Minvielle et al. reported a low proportion of women (19.1%) compared with 80.9% of men [13] , and Samayoa et al. found that women were 36% less likely than men to participate in a CR programme [14] . This lower level of female participation in exercise could result from grandmothers displaying less interest and having fewer opportunities such as the inability to attend frequently due to familial commitments.
Functional capacity is a strong predictor of all-cause mortality and cardiovascular events. Adequate exercise has beneficial effects in both primary and secondary prevention. An increase in functional capacity of 1 metre (3.5 ml/mn/kg oxygen) was associated with a reduction in mortality of almost 15% [15] . In our series, functional capacity improved by 49.39% before and after re-training, with a mean increase from 5.81 ± 2.38 Mets pre-CR to 8.68 ± 2.28 Mets post-CR (p < 0.001). Our results are similar with studies that have shown a significant improvement in physical performance in elderly subjects after rehabilitation [16] . This exercise capacity, expressed in metabolic equivalents (Mets), increased by 34% in the first study and by 43% in the second.
In fact, the decline in exercise capacity associated with the ageing of the cardiovascular system is an inexorable fact from which no one can escape. However, the rate of decline is individual and depends on a number of risk factors and pathologies. A sedentary lifestyle (less than 30 minutes of continuous physical activity per week outside work) is certainly one of the main causes of cardiac dysfunction. This modern scourge affects a significant proportion of the population: 35% of the under-34s and 45% of the over-65s [17] . If we want to combat the harmful effects of ageing and practice effective and inexpensive prevention of cardiovascular disease, we need to promote regular physical activity [17] [18] . Heart and Health Clubs in cardiology clinics or other coronary heart disease club structures can provide effective support for long-term motivation.
In our study, the 6-minute walk test was performed in 12 patients (10.32%) pre-CR and in 4 patients (3.44%) post-CR. There was a clear improvement in the results of this test, with mean values increasing from 330.42 ± 170.50 m pre-CR to 524 ± 98.54 m post-CR (p = 0.119). Despite the low rate of performance of this test in our population, our results are consistent with those of Peneroni et al. [19] who found a significant increase in maximal aerobic capacity during the 6-minute walk test with an increase in distance covered and a reduction in Borg symptom scores for dyspnoea after cardiac rehabilitation in elderly patients with chronic heart failure.
The assessment of independence in older people is usually based on several types of tools. In our study, we found a significant improvement (p = 0.001) in the degree of autonomy in our population before and after the CR programme, both in activities of daily living, as shown by the Katz index, and in those involving instrumental functions, as shown by the Lawton index.
Elderly patients are fragile and, as they age, they approach the threshold of dependence and loss of autonomy. This threshold can be reached in the event of an acute illness, particularly heart disease, or surgery.
We chose to assess quality of life using the SF12 questionnaire, administered or self-administered before and after the CR programme. In our study, the physical quality of life score (PCS-12) improved from a mean of 41.61 ± 10.69 before CR to a mean of 61.30 ± 7.78 after CR (p < 0.001). Our results were in agreement with those of Corone et al.. [20] who showed a significant reduction in anxiety from 9.3 ± 5.1 to 6.6 ± 4.2 (p < 0.05), depression from 6.5 ± 7.7 to 3.8 ± 6.3 (p < 0.001), fatigue from 6.3 ± 5.3 to 4.2 ± 4.3 (p < 0.001) and confusion from 5.9 ± 3.3 to 5.2 ± 2.9 (p < 0.001) after rehabilitation. In our study, the mental quality of life score (MCS-12) also improved significantly from a mean of 42.15 ± 10.27 before CR to a mean of 52.94 ± 10.86 after CR (p < 0.001). Our results are in agreement with those of Choo et al. [21] , who found a significant improvement in MCS-12 in Asian patients, with the mean increasing from 49.95 ± 7.89 pre-CR to 52.48 ± 5.90 post-CR (p < 0.001). Elderly patients admitted for CR are aware of the benefits of this programme, both physically and psychologically.
There are some limits in this study, we did not find a specific scale in the literature to assess the autonomy of older people in CR, which explains our use of the Katz and Lawton scales and the collection of these results during a clinical interview and a telephone survey. This may open the debate on the interest of developing in the future a specific grid that is simpler, more sensitive to the African population and more suitable for use in CR to assess the autonomy of the elderly [22] [23] . Furthermore, in the absence of a control group, it is not possible to conclude that it is our cardiac rehabilitation programme that is the determining factor in the improvement of the patients compared with another treatment or compared with the time elapsed.
5. Conclusion
Our study has demonstrated the value of cardiac rehabilitation in older people. In fact, this programme, which is well managed, structured and supervised, allows this population to regain their autonomy, improve their quality of life and functional capacity, and thus their prognosis. However, the number of patients enrolled in this programme remains limited due to a lack of information or knowledge among physicians about the benefits of cardiac rehabilitation, inadequate prescribing and a lack of resources.