Cardiac Risks and Benefits in Swimmers. W. Stewart Hillis

Cardiovascular Risk; Exercise and Mortality 1 in 22 studies showed significant improvement. Problems of small groups and short term follow up Recent meta analysis confirms 20% reduction in mortality Undoubted improvement in exercise capacity and quality of life

Cardiovascular Risks; Training Benefits Weight reduction with improved glucose tolerance Improved lipid profile changes in HDL and LDL and triglycerides Beneficial effects of platelet function. Benefits in muscle function enhances capillary density, enhanced oxygen extraction, altered oxidative enzyme content and enhanced mitochondrial function Psychological benefits both in health and disease.

Cardiovascular Risk; Exercise Prescription Physical activity an independent risk factor for cardiovascular disease and all cause mortality. Evident in both occupational and recreational activity. Conflicting evidence concerning dose response or modest intervention only. ‘No pain no gain’ or 30 minutes of moderate activity on most days of the week. Major problems of compliance.

Energy Expenditure in Swimming. Energy expended to maintain buoyancy and generating horizontal movement. Overcoming drag forces of fluid medium influenced by size, shape and velocity. Thermal stress metabolic and cardiovascular adjustment. Shivering may occur to maintain core temperature.

Problems Associated with Swimming Problems of emersion particularly in cold. Increased sympathetic activity increased demands on myocardium in coronary artery disease and hypertension. Vagal over activity associated with the diving reflex with bradycardia, reduced cardiac output and intense vasoconstriction which may induce diastolic dysfunction. Lactate accumulation in muscle Immersion may be associated with atrial and ventricular arrhythmias.

Swimming benefits. Single bout of ultra endurance exercise Reduction in triglycerides 39%,total cholesterol 9% LDL decreased by 11% with reduced propensity to peroxidation Ginsberg et al JAMA;27:63: Echocardiography studies show increased stroke volume and oxygen consumption in trained subjects. Morris et al Sports Med.16;(4):

Swimming In Heart Failure Water immersion leads to increase in intra thoracic circulation With emersion heart failure patients increased cardiac output by 16%, compared to 21% in CAD and 19% in controls. Cardiac index increased by 53%, 77% and 87% respectively. Selection by exercise testing VO2 of 15ml/kg/min Schmid et al Card Prev and Rehab 93(6):722-7;2007

Swimming for Acute Myocardial Infarction Patients. National Exercise and Heart Disease Project. 19 year survival in 30 to 64 year olds Randomised to structured exercise or control. Each 1 met increase in exercise capacity from work capacity from baseline to end of trial showed a reduction in all cause and CVD mortality. Benefits reduced with time raising question of short term effects and compliance. Dorn et al Circulation100:(17);

Cardiovascular Risk; Exercise Testing Review of 167 programmes of rehabilitation. 1.3 fatal events per million hours of activity 3.4 myocardial infarctions 8.9 resuscitations

Cardiovascular Risk Related to Exercise Uncommon; 2 cases per 100,000 subject years 5 in 100,000 have a predisposing cardiac condition 10% (1 in 200,000) of those at risk die suddenly Causes of death similar in different countries and different sports.

Cardiovascular Risk; Screening Issues Sports participants highly motivated; Implications for earnings Classification of high and low intensity sports Concept of dynamic and static components Contact and non contact sports. Risks of prosthetic valve dehiscence. Anti- coagulants Particular risks with syncope in water borne sports

Cardiovascular Risk; Preparticipation Screening Remains controversial over appropriateness cost and practicality. Identification of those at risk. Targeting of those; Family history of sudden death. Premature coronary artery disease. Known structural abnormality Education of those with symptoms Syncope, presyncope, palpitation, chest pain and dyspnoea. Guidelines for disqualification from sport.

Questionnaire Specific health related questionnaire regarding family history of sudden death or premature cardiovascular disease. Symptomatic enquiry regarding warning symptoms.

Abnormal ECGs In Trained Athletes. Most athletes (60%) have normal electrocardiograms Variety of abnormal tracings usually indicative of physiological cardiac remodelling. 30% in swimmers A small proportion have striking abnormalities but normal cardiac morphology as assessed by echocardiography. 15% in swimmers Such false positives suggest the limitation of the electrocardiogram if used in screening. Pelliccia et al Circulation 2000;102: % normal in nontrained preparticipants Eur Heart J.28(16)

Conditions with Known Cardiovascular Risk < 35 yrs Hypertrophic cardiomyopathy Idiopathic concentric L.V. hypertrophy Anomalies of coronary arteries Aortic rupture Right ventricular dysplasia Myocarditis Valvular disease Arrhythmias and conduction defects

Cardiovascular Risk; Hypertrophic Cardiomyopathy Leading cause of sudden unexpected death in young athletes Hypertrophied, non dilated left ventricle No predisposing cause for hypertrophy Chamber size reduced, impaired diastolic filling Outflow tract obstruction; Hypertrophy of sub aortic septum. Systolic anterior motion of mitral valve

Cardiovascular Risk; Hypertrophic Cardiomyopathy Autosomal dominant; high degree of penetrance Predisposition to s.v. and ventricular arrhythmias Symptoms of chest pain. palpitation, syncope and dyspnoea Signs; Jerky pulse, double apex beat, 4th heart sound, systolic murmur ECG useful, Echo diagnostic

Cardiovascular Risk; Hypertrophic Cardiomyopathy Adverse prognostic factors include: 1. Family history of sudden death 2. Documented ventricular tachycardia 3. Young age of onset of symptoms

Cardiovascular Risk; Athlete Heart or HCM Septal thickness 15mm Septal free wall ratio <1.3 or.1.3 mm LV End diastolic dimension; increased or decreased Ejection fraction normal or increased Abnormal ECG in 25-50% of AH, 90% in HCM Problems associated with the Gray zone

Conditions with Known Cardiovascular Risk < 35 yrs Hypertrophic cardiomyopathy Idiopathic concentric L.V. hypertrophy Anomalies of coronary arteries Aortic rupture Right ventricular dysplasia Myocarditis Valvular disease Arrhythmias and conduction defects

Cardiovascular Risks; Arrhythmias and Heart Block Mechanism of sudden death arrhythmic, Disorders of automaticity, conduction or repolarisation Autonomic changes during sporting activity Arrhythmias associated with structural abnormalities

Cardiovascular Risk; Arrhythmias Exercise induced ventricular arrhythmias Pre-excitation in Wolff-Parkinson-White syndrome Repolarisation abnormalities in the prolonged QT syndrome Brugada syndrome and other channelopathies. R.V. arrhythmias associated with previous right ventriculotomy

Conditions with Known Cardiovascular Risk > 35 Yrs Coronary artery disease Special problems of congenital heart disease, operated or unoperated

Cardiovascular Risk; C.A.D. Major cause of death in > 35 years Most deaths occur in vigorous sports Previous symptoms suggestive of coronary atherosclerosis recognised Risk factors often present Victims perceived as very fit and type A personalities

Cardiovascular Risk; C.A.D. Pathology confirms obstructive coronary artery lesions Myocardium may show previous healed infarct Not prevented by extreme forms of conditioning Education for warning symptoms of chest pain, palpitation or syncope

Cardiovascular Risk; Classification of Sports High to moderate dynamic & static demands: Boxing, Cycling,Fencing, Football,Handball, Ice hockey, Rowing, Rugby, Running, Skiing (downhill), Speed skating, Water polo, Wrestling High to moderate dynamic & low static demands: Badminton, Basketball, Hockey, Squash,Soccer, Swimming, Tennis, Table Tennis

Cardiovascular Deaths in the Young. In Scotland Central registration of deaths. 42 males and 23 females died of acute circulatory problems aged less than 25 years. If screening 16 year olds 33,439 males and 31,916 females. Impractical to apply screening to whole population. Problem perceived of access to facilities for screening.

Screening Programmes. In United States pre participation screening advocated for high school and college aged students on ethical, legal and medical grounds. History and physical examination targeted to conditions with known risk, but without the use of non-invasive assessments. ‘Addition of non invasive testing would undoubtedly enhance detection of many responsible lesions but unrealistic on a national scale owing to prohibitive costs and other practical details.’ Maron.

Screening Programmes. Italian model. Pre participation screening required for all young adults participating in organised sports. Follow up study in 33,735 in Veneto region of Italy Screened using a questionnaire, physical examination and an ECG. If indicated echo performed. 8.2 years of follow up. 3,016 echoes performed 561 subjects disqualified rhythm and conduction problems, hypertension, valvular disease and cardiomyopathy. Corrado et al NEJMed 339:364; 1998.

Italian Experience. 269 sudden deaths, 49 in competitive athletes 22 cases of hypertrophic cardiomyopathy diagnosed. No deaths in athletic group. 16 deaths in non athletic population from HCM none previously screened.

Screening. Regarded as not appropriate on a cost basis. Recommended by FIFA and UEFA and European agencies. A challenge to governing bodies with regard to duty of care.