Physical activity can reduce mortality from cardiovascular disease, enhance physical fitness and improve quality of life, and is an effective and cost-effective physiologic approach to disease prevention and treatment. However, sudden death from exercise is often the first manifestation of underlying cardiovascular disease, and the tolerance to exercise varies among patients with cardiovascular disease, and intense exercise in some patients will greatly increase the transient risk of acute myocardial infarction (AMI) and sudden cardiac death (SCD). Therefore, people with cardiovascular disease need to be aware of their heart disease and have some knowledge about sports. Experts recommend that this group of people participate in sports preferably after a thorough evaluation by a cardiovascular specialist and selective participation in sports of appropriate intensity and duration.
Sports are usually divided into sports training for the purpose of competition and fitness and rehabilitation for the general public. Both competitive sports and mass fitness sports are associated with certain exercise risks, 80% of which are related to the cardiovascular system. Therefore, the selection of appropriate projects, exercise intensity and exercise time for athletes for sports training, the general public to participate in fitness and rehabilitation and medical rehabilitation are of great importance.
People who participate in mass fitness exercise should choose the appropriate intensity of aerobic exercise according to their age and physical condition. Mainly include: walking, jogging, tai chi, aerobic exercise, fitness dance, walking and running alternately, up and down stairs, swimming, bicycles, power bicycles, walking cars, running platform, rope skiing, rowing, ice skating, skiing, ball sports. Exercise is characterized by low intensity and long duration, which can increase the body’s inhalation, transport and use of oxygen, improve the body’s oxygen consumption, and improve the function of the respiratory and cardiovascular systems. In addition, most communities in China have now popularized fitness paths, which are a good way for the public to train for strength.
Overly strenuous exercise may promote acute myocardial infarction (AMI) and sudden death. Exercise-related cardiovascular events are significantly higher in patients with diagnosed coronary artery disease. There is conclusive evidence that strenuous exercise dramatically increases the risk of cardiovascular events in young adults or adults with occult and clearly diagnosed heart disease. The increased risk of cardiovascular events with vigorous exercise may occur during or after exercise. This is primarily due to a combination of underlying cardiac disease and exercise-triggered stress responses, including emotional stress, altered hemodynamics, altered parasympathetic tone, and myocardial ischemia. As mentioned above, sports training itself may increase the risk of sudden death in young athletes with cardiac disease. Sports training increases the risk of arrhythmias by accelerating the disease process, affecting cardiac structure or electrophysiological changes, and worsening the disease. For example, in patients with hypertrophic cardiomyopathy, repetitive and intense training can continuously cause myocardial apoptosis and myocardial fibrosis, resulting in increased instability of ventricular electrical activity. In patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia, repetitive high-intensity physical activity can increase right ventricular volume load, increase right ventricular volume, and worsen fatty fibrosis. In patients with Marfan syndrome, the increased blood pressure and volume per beat during exercise act on the aorta, causing active dilation and increasing the risk of aortic dissection. Thus, in young and adult patients with cardiovascular disease, there is a difference in the risk-to-benefit ratio of exercise.
Exercise cardiovascular events are somewhat rhythmic. In adults AMI and SCD occurring events tend to occur in the early morning. Sudden death and cardiac arrest in young athletes occur more often in the afternoon and evening compared to adults and are associated with training and competition. However, in non-athletes with hypertrophic cardiomyopathy, sudden death tends to occur within a few hours of awakening in the morning, similar to coronary artery disease, for reasons that have not been rationally explained. The preferred timing of cardiovascular events in young people with other genetic disorders cannot yet be determined.
For recreational exercise, cardiovascular physicians should conduct a comprehensive assessment of patients with cardiovascular disease, taking into account both the disease itself and the specificity of the exercise, recommend reasonable exercise regimens, and avoid high-risk exercise programs so that patients can both enhance their fitness through exercise and reduce the incidence of cardiovascular events and reduce the incidence of exercise-related sudden death.
Patients with cardiovascular disease should first undergo risk assessment before exercising. The risk of exercise in patients with cardiovascular disease is divided into two groups: low risk group: no signs and symptoms of heart failure; NYHA cardiac function class 1 to 2; no electrocardiographic manifestations of angina or myocardial ischemia in quiet; good exercise tolerance (>= 6 MET); no myocardial ischemia at low load (< 6 MET); normal increase in exercise heart rate and blood pressure; no complex arrhythmias in quiet and/or exercise; EF > 50%. High-risk group: one of the following conditions, signs and symptoms of heart failure; NYHA cardiac function class 3-4; poor exercise tolerance (<6 MET); angina pectoris or ischemic changes on ECG at low load (<6 MET); abnormal increase in exercise heart rate and blood pressure; complex arrhythmias during quiet and/or exercise; EF <35%-40%; history of cardiac arrest (not due to temporary causes).
Physical activity should not be performed in the following conditions: unstable angina, severe valvular stenosis or insufficiency, progressive heart failure, uncontrolled arrhythmias, recent embolic events, acute stages of pericarditis and myocarditis, and severe uncontrolled hypertension.
Physical activity in patients with cardiovascular disease should be recreational or therapeutic in nature. The amount of activity must be based on the individual’s exercise tolerance, which is assessed by clinical and objective examination. Furthermore, exercise should be progressive according to a plan; preferably quantifiable; and engaged in those exercises that are easy to perform. The ideal forms of exercise are those that are vigorous, have a fixed surface, and have a low to moderate cardiovascular demand such as walking, running, and cycling. Exercise prescription for patients with cardiovascular disease should take into account the following factors: frequency of exercise per week, intensity, absolute average of energy expenditure during training, duration of exercise, monitoring criteria, and interaction between exercise and therapeutic medications. It has been found that exercise intensities of 60% to 75% VO2max and heart rates of 70% to 85% of maximal exercise are required to improve the adaptability of the cardiovascular system. If the exercise intensity exceeds 80% of VO2max, the risk of cardiovascular events outweighs the benefit of exercise. High-intensity exercise should only be performed in certain low-risk patients.
All types of exercise are contraindicated in congenital long QT interval syndrome, even if no significant arrhythmic events have been recorded. In patients who have had out-of-hospital cardiac arrest or LQTS-associated syncope, only low-load static and powered exercise should be performed, regardless of QTc length and genetic mutation type. ICD therapy should be fitted in high-risk patients to reduce mortality. Once an ICD is fitted the guidelines for ICD patients should be followed .
Patients with pacemakers who do not show signs of heart disease can participate in competitive sports with low cardiovascular demands, i.e., exercise tests and 24-hour ambulatory ECG monitoring reveal an appropriate increase in heart rate during exercise. However, such patients should limit sports with a risk of physical collision, such as soccer, basketball and baseball. This is because this may damage the electrodes and pacing device. Furthermore, close attention should be paid to avoid possible electromagnetic interference. Sports with inappropriate acceleration of frequency such as equestrianism should not be participated in. Extensive exercise of the ipsilateral upper extremity should be performed only after the electrodes have been completely fixed 6 weeks after pacemaker implantation. Sports with vigorous ipsilateral limb activity such as volleyball, basketball, tennis and rock climbing carry the risk of motor dislocation or relaxation due to subclavian pressure build-up.
Asking for a family history and ECG is the most common and practical method for patients with cardiovascular disease or potential cardiovascular disease to participate in sports. Individuals with a family history of syncope should be alert for cardiac syncope, and cases of sudden death in the young (<35 years of age ) in the family should exclude hereditary arrhythmias and cardiomyopathies.
ECG is a simple, easy and sensitive means of screening for early warning indicators, and ECG early warning indicators include the following.
1.J wave
J wave syndrome is a group of clinical symptoms characterized by J waves on ECG, including Brugada syndrome, idiopathic ventricular fibrillation, acute coronary syndrome and early repolarization syndrome.
J-wave formation is due to an absolute or relative increase in the transient outward potassium current (Ito) in phase 1 of the epicardial cardiomyocyte action potential. The consequence is an increase in intra- and extra-ventricular membrane potential difference and repolarization dispersion, which can easily lead to 2-phase folding. 2-phase folding is manifested on the ECG as R-on-T ventricular premature, which can easily induce malignant ventricular arrhythmias.
2.QT interval abnormalities
QT interval abnormalities mainly include long QT interval syndrome (QTc > 450 ms [male]; > 460 ms [female]) and short QT interval syndrome (QTc < 300 ms).
Both long and short QTs are at risk of potentially malignant arrhythmias, and both increase mortality in patients. The risk of sudden death in those with long QT interval is 2.3 times higher than that in those with normal QT, while the risk of sudden death in those with short QT is 2.4 times higher than that in those with normal QT interval.
3.T-wave alternans (TWA)
TWA refers to the beat-to-beat alternating changes in the amplitude and morphology of T waves on the ECG. In addition, there is still a microvoltage level difference in amplitude between seemingly morphologically consistent T waves under certain conditions, also known as microvoltage level TWA.
TWA may be related to action potential timing, intracellular calcium cycling, and neuromodulation. The risk of arrhythmia is four times higher in TWA-positive patients than in TWA-negative patients.
4. Heart rate variability (HRV)
HRV is an objective indicator reflecting the autonomic regulation of the heart. Its judgment indicators mainly include two categories: time domain indicators and frequency domain indicators. The decrease of HRV indicates the damage of cardiac autonomic nerve, which may lead to myocardial electrical instability and lower threshold of ventricular fibrillation, thus increasing the chance of malignant arrhythmia and sudden cardiac death. Some studies have reported that its warning effect on malignant arrhythmias and sudden cardiac death in patients with myocardial infarction is significantly better than that of LVEF, late ventricular potentials and cardiac function class.
5.epsilon wave
The presence of epsilon waves, which are small sharp waves in the form of single, double or triple peaks immediately after QRS, means that a patient with ARVD/C is likely to have epsilon waves. Such patients are at risk for potential ventricular tachycardia and are one of the leading causes of sudden death in adolescent sports.
In conclusion, whether participating in competitive sports or mass fitness sports, participants must choose exercises that are suitable for them and of appropriate intensity according to their family history, ECG and the presence of underlying cardiac disease and the severity of the underlying disease, as well as adjusting the amount and duration of exercise according to their own feelings and experiences during the exercise. Patients with underlying cardiac disease or ECG abnormalities must exercise under the guidance of a cardiovascular specialist, and must not exercise blindly or with excessive intensity.