Cardiac risks of exercise Flashcards
What is the general consensus on risk of dying from a heart attack during exercise?
Absolute risk of dying from a heart attack during exercise is very low
* There is general consensus that vigorous exercise acutely, albeit transiently, increases the risk of SCD, but only in individuals with underlying cardiac disease, either occult or manifest
What population is at greatest risk of MI from vigorous exercise?
- Risk is highest in those that do not do vigorous exercise, and lowest in those that do it frequently
- Everyone is at high risk when they are exercising, more likely to have a heart attack than at rest
- Cardiac biomarkers are acutely increased by exercise, and atrial fibrillation, myocardial fibrosis, and coronary artery calcification appear more common in older athletes compared with their inactive peers
What is the relative risk of sudden death during vigorous exercise?
How do the acute effects differ for long-term mortality?
- The risk of an exercise-related SCD using the individual case-control study was 16.9% higher during vigorous exercise
- The absolute risk of an exercise-related SCD was extremely low, however, at only 1 death per 1.42 million hours of vigorous exercise.
- Exercise causes an acute increase in SCD risk, although leads to an ultimate reduction in risk of SCD
What is the recommended amount of exercise for an adult per week?
Recommendation that adults perform moderate-intensity exercise for a minimum of 30 min daily at least 5 days a week, or vigorous-intensity exercise for a minimum of 20 min daily at least 3 days a week
What is the greatest cause of cardiac arrest in long-distance runners?
None survivors involve hypertrophy cardiomyopathy ~ 50%
- Enlargement of the heart(left side) and muscle
- the walls of the heart’s ventricles become abnormally thickened, making it harder for the heart to pump blood efficiently.
- Mainly swim part of triathlon is the largest cause of death due to it being sporadic
What factors increase a persons risk of CV event during acute exercise?
- vigorous exercise transiently increases risk of sudden death and MI
- hereditary/congenital CV abnormalities are mainly responsible for cardiac events in young people
- Atherosclerosis disease is primarily responsible for CV events in adults
- MI and sudden death from acute exercise is highest in people that are unaccustomed to exercise or have hereditary CV abnormalities.
What is the relationship between all-cause mortality and running distance per week?
- People who are inactive(0 miles per week) have the highest hazard ratio for all-cause mortality
- People who are overactive(>25 miles per week) have the second highest mortality rate.
- U curve, so moderately active people have the lowest chance of all-cause mortality.
- seems more linear in females
What are the benefits of regular exercise?
- habitual exercise reduces CHD risk
- Lower risk of all-cause mortality in light to moderate joggers
- Risk in strenuous joggers is 2x higher than other exercisers
- Very large error margins
What is aterial fibrillation?
How can AFib induce CAD events during exercise?
- when the upper & lower chambers of the heart are not coordinated, causing the heart to beat too slowly, too quickly or irregularly.
- Plaque disruption during exercise is attributed to exercise-related increases in shear forces as well as increases in the bending and flexing of coronary arteries during exercise. The flexing of the coronary arteries is increased during exercise by the increase in heart rate, rupturing the plaque causing CAD events
What are some side effects of AF?
- Lowers stroke volume and cardiac output
Impairs capacity to exercise - decreases stroke volume & cardiac ourput = stroke due to atria not ejecting blood, so blood pooling and clotting in atria. Causes a clot, which goes through circulation and can make its way to the brain cutting off blood flow
Why is it important to exercise at a safe level to prevent AF?
- Moderate levels of exercise reduce the risk of AF
- Very high physical activity levels increase the risk of AF, but the effect is modest, and there is no effect on mortality
- There is no firm threshold or guideline that can be drawn from the existing literature in terms of the association between exercise and AF.
- Can be resolved through atrial ablation - the creation of scar tissue, blocking abnormal electrical signals that cause irregular heartbeats.
What condition links exercise with heart damage?
Hypertrophic cardiomyopathy (HCM):
* An inherited disease of the heart muscle
* The heart muscle walls (left and right ventricle) are thickened
* Thickened walls compromise cardiac function = AFiB
* HCM can also lead to dangerous cardiac arrhythmias
* About 1 in 500 of the UK population has HCM
what is atrial flutter?
- upper chambers (atria) to pump rapidly, leading to a heart rate that is faster than normal.
- intermediate to AFiB
How can LV wall thickness differ among individuals?
What can hypertrophic cardiomyopathy lead to?
- Thicker walls causes smaller chamber size
- Female athletes have smaller LV and LA diameters and are less likely to demonstrate LV wall thickness
- LV wall thickness is also greater in black athletes
- Strength trained athletes have thicker LV wall, but endurance performers have increase L&RV capacity
- Excessive exercise combined with a condition termed ‘hypertrophic cardiomyopathy’ may trigger a cardiac arrest
What is cardiac troponin?
What are the exercise-induced increases in cardiac troponin levels?
- A protein found in cardiac muscle
- A biomarker for diagnosing MI, healthy levels are very low but increase after cardiac injury.
- muscle damage by exercise causes expression of cTn, which enters the circulation = potential irreversible myocardial cell apoptosis
- detected in all marathon runners
- caused by damage and leakage of heart after exercise
- exercise intensity is the strongest predictor of cTn release
