Hypertension in Special Populations: Athletes

Rosa Maria Bruno; Giulia Cartoni; Stefano Taddei

Future Cardiol. 2011;7(4):571-584.

Abstract and Introduction

Abstract

Physical exercise is known to lower blood pressure and reduce cardiovascular risk through a wide range of mechanisms. Nevertheless, hypertension is the most prevalent cardiovascular disease among athletes and physically active subjects. This article reviews the state of the art in practical approaches to this issue, focusing on special aspects a physician should take into account when diagnosing hypertension, such as screening of secondary causes, assessment of global cardiovascular risk and target organ damage and, in addition, the treatment choice in athletes.

Introduction

Arterial hypertension, although becoming increasingly more frequent with aging, is the most prevalent cardiovascular risk factor in each age-class. Its prevalence is about 29% in the US population aged >18 years.^[1] A linear relationship has been demonstrated for each age-class between systolic and diastolic blood pressure values and cardiovascular morbidity and mortality, as well as heart failure, peripheral artery disease and end-stage renal disease.^[2] For these reasons, arterial hypertension represents the leading cause of death in the world according to the WHO.^[3] Given the linearity of the relationship between blood pressure values and cardiovascular risk, with no evidence of threshold up to 115/75 mmHg, any classification and definition of hypertension appears to be arbitrary. Nevertheless, for practical reasons, in order to make diagnosis and treatment easier, a conventional classification is used: in particular, arterial hypertension is defined by systolic and/or diastolic blood pressure values equal to or greater than 140/90 mmHg.^[4] As illustrated in Table 1, arterial hypertension can be classified according to severity of blood pressure values; interestingly, an intermediate category, named high-normal blood pressure, is defined: although it was suggested that people with high-normal blood pressure and high cardiovascular risk could be considered and treated as hypertensive patients,^[4] the most recent reappraisal of European guidelines recommend more caution and discourages the use of aggressive approaches.^[5] It is also important to notice that this classification refers to office blood pressure, that means blood pressure measured in a clinical setting by a physician or a nurse, while home and 24-h blood pressure reference values are lower.^[4]

Athletes are usually young individuals appearing to be in good health, who perform systematic physical exercise at high intensity. Accordingly, this is a population at low cardiovascular risk. The number of athletes who die of cardiovascular or related causes each year in the USA is probably less than 300, compared with the large number of athletes participating in a broad spectrum of organized sports (about 10 to 15 million) of all ages in the USA.^[6] The incidence of sudden cardiac death in young competitive athletes (<40 years) in the USA is even lower, approximately 66 per year.^[7,8] Despite their rarity, such deaths are highly emotional events, since they frequently occur while the subject is engaged in athletic activity and involve young and otherwise healthy individuals. The main causes of cardiovascular death are congenital or idiopathic diseases, including hypertrophic cardiomyopathy (36%) and congenital coronary artery abnormalities, as well as traumatic events.^[7,8] Hypertension itself is not associated with an increased risk of sudden cardiac death. However, coronary heart disease has been identified in the great majority of exercise-related sudden deaths above the age of 40.^[9] Moreover, the various different sports do not provide equal cardiovascular protection. A survey conducted in 2049 Finnish elite male athletes demonstrated that former athletes who had performed endurance or mixed sports during youth had a lower rate of hospitalization for ischemic heart disease as compared with controls, while power sports athletes (boxing, wrestling, weight lifting) were at an even greater risk than sedentary subjects.^[10] In this complex scenario, the issue of hypertension in athletes should not be disregarded, for several reasons. First, although prevalence of hypertension in athletes is still an unresolved issue, it is reasonable to estimate that it is approximately 50% lower among sports practitioners than in the general population.^[11] Thus, arterial hypertension is the most prevalent cardiovascular condition even in athletes.^[12] Furthermore, increased life expectancy and quality, and growing attention to fitness and lifestyle measures to counteract cardiovascular disease in Western countries, is leading to a non-negligible number of physically active aged subjects, in whom classical cardiovascular risk factors are expected to be well represented. Thus, specialists in hypertension and sports medicine are very likely to encounter such patients in their everyday activity, with two main roles:

To apply the classical principles of cardiovascular prevention to this subset of population. Indeed, almost all sudden cardiac deaths above the age of 40 years occurred in subjects presenting cardiovascular risk factors,^[9] thus it is likely that these deaths would have been prevented with standard treatment.
To diagnose and treat hypertension and, more generally, assess global cardiovascular risk, which is mandatory for a decision on sports eligibility.

It is also important to consider that hypertension per se can limit exercise performance: untreated hypertension can decrease exercise capacity, by means of impairment of left ventricular diastolic filling, regardless the presence of left ventricular hypertrophy or diastolic/systolic dysfunction at rest;^[13–15] furthermore some antihypertensive medications can impair cardiovascular adaptation to exercise. This article aims to clarify, in a user-friendly style, the key concepts involving pathophysiological aspects, specific features in diagnostic evaluation, criteria for sport eligibility, effect of performance-enhancing drugs on the cardiovascular system, target organ damage assessment and therapeutic choices.

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Abstract and Introduction
Effects of Exercise on Cardiovascular Risk
Clinical Evaluation
Treatment
Conclusion
Future Perspective
References
Sidebar

Table 1. Definition and classification of blood pressure levels.
Category	Systolic blood pressure (mmHg)		Diastolic blood pressure (mmHg)
Optimal	<120	and	<80
Normal	120–129	and/or	80–84
High normal	130–139	and/or	85–89
Grade 1 hypertension	140–159	and/or	90–99
Grade 2 hypertension	160–179	and/or	100–109
Grade 3 hypertension	≥180	and/or	≥110
Isolated systolic hypertension	≥140	and	<90

Adapted with permission from [4].

Table 2. Stratification of cardiovascular risk according to blood pressure values and the presence of the cardiovascular risk factors: organ damage, presence of metabolic syndrome or diabetes or established cardiovascular or renal disease.
Risk factors, organ damage, diseases	Normal blood pressure	High–normal blood pressure	Grade 1 hypertension	Grade 2 hypertension	Grade 3 hypertension
No other risk factors	Average risk	Average risk	Low added risk	Moderate added risk	Very high added risk
1–2 risk factors	Low added risk	Low added risk	Moderate added risk	Moderate added risk	Very high added risk
>2 risk factors, metabolic syndrome, diabetes and/or organdamage	Moderate addedrisk	High added risk	High added risk	High added risk	Very high added risk
Established cardiovascular or renal disease	Very high addedrisk	Very high addedrisk	Very high added risk	Very high added risk	Very high added risk

Adapted with permission from [4].

Table 3. Classification of sports.
	Low dynamic	Moderate dynamic	High dynamic
Low static	Low total cardiovascular demands: Bowling Cricket Golf Riflery	Low–moderate total cardiovascular demands: Fencing Table tennis Tennis (doubles) Volleyball Baseball†/softball†	Moderate total cardiovasculardemands: Badminton Race walking Running (marathon) Cross-country skiing (classic) Squash†
Moderate static	Low–moderate total cardiovascular demands: Auto racing†,‡ Diving‡ Equestrian†,‡ Motorcycling†,‡ Gymnastics† Karate/Judo† Sailing Archery	Moderate total cardiovascular demands: Field events (jumping) Figure skating† Lacrosse† Running (sprint)	High–moderate total cardiovascular demands: Basketball† Biathlon Ice hockey† Field hockey† Rugby† Soccer† Cross-country skiing (skating) Running (mid/long distance) Swimming Tennis (single) Team handball†
High static	Moderate total cardiovascular demands: Bobsledding†,‡ Field events (throwing) Luge†,‡ Rock climbing†,‡ Waterskiing†,‡ Weight lifting† Windsurfing†,‡	High–moderate total cardiovascular demands: Body building† Downhill skiing†,‡ Wrestling† Snow boarding†,‡	High total cardiovascular demands: Boxing† Canoeing/kayaking Cycling†,‡ Decathlon Rowing Speed skating Triathlon†,‡

The increasing dynamic component is defined in terms of the estimated percentage of maximal oxygen uptake achieved and results in an increasing cardiac output (low: <40%; moderate: 40–70%; high: >70%). The increasing static component is related to the estimated percentage of maximal voluntary contraction reached and results in an increasing blood pressure load (low: <20%; moderate: 20–50%; high: >50%). †Danger of bodily collision.‡Increased risk if syncope occurs.Adapted with permission from [57].

Table 4. Recommendations for competitive sport participation in atheletes with arterial hypertension.
Level of risk	Criteria for eligibility	Recommendations	Follow-up
Low added risk	Well-controlled BP	All sports	Yearly
Moderate added risk	Well-controlled BP and risk factors	All sports, with the exclusion of high static/high dynamic sports	Yearly
High added risk	Well-controlled BP and risk factors	All sports, with the exclusion of high static sports	Yearly
Very high added risk	Well-controlled BP and risk factors, no established cardiovascular disease	Only low–moderate dynamic/low static sports	6 months

BP: Blood pressure.
Adapted with permission from [54].

Table 5. Pharmacologic treatment fot hypertension in athletes and other physically active patients.
Drug class	Considered as doping substance	Impairment of sport performance	Conditions favoring its use	Contraindications	Indications in athletes
Thiazide diuretics	Yes	Yes (hypovolemia in first weeks)	Isolated systolic hypertension in the elderly, heart failure, hypertension in black subjects	Gout	Second or third choice, at lowdosage
Loop diuretics	Yes	Yes (hypovolemia, ortostatic hypotension, electrolyte imbalance)	Chronic renal failure, heart failure	–	Second or third choice, at lowdosage
Potassium-sparing diuretics	Yes	Yes (hypovolemia)	Heart failure, primary aldosteronism	Chronic renal failure, hyperkalemia	Associated with thiazide/loop diuretics if in case of hypokalemia
b-blockers	Yes	Yes (negative chronotropic and inotropic effect, energy metabolism impairment)	Heart failure, postmyocardial infarction, angina, tachyarrhythmias, pregnancy	Asthma, grade 2–3 AV-block	Use only when is mandatory; a-b-blockers preferred
Renin–angiotension system blockers	No	No	Heart failure, postmyocardial infarction, diabetic nephropathy, proteinuria/microalbuminuria, left ventricular hypertrophy, carotid atherosclerosis, atrial fibrillation, metabolic syndrome	Pregnancy, hyperkalemia, bilateral artery stenosis	First choice
Calcium antagonists	No	No	Isolated systolic hypertension, left ventricular hypertrophy, carotid atherosclerosis, pregnancy, hypertension in black subjects	–	First choice
α-blockers	No	No	Benign prostatic hypertrophy	Ortostatic hypotension	Second or third choice

Sidebar

Executive Summary

Epidemiology

Cardiovascular death in athletes is mainly attributable to sudden cardiac death in subjects below 40 years and to ischemic heart disease after the age of 40 years.
The real prevalence of hypertension in athletes is unknown, but it is estimated to be approximately half of the general population, with differences between sports categories.

Effects of exercise on cardiovascular risk: observational & interventional studies

Observational studies demonstrated that low fitness is an independent predictor of cardiovascular mortality.
Endurance training is beneficial for several cardiovascular risk factors.
The benefit of resistance training is less established, but can be safely associated to endurance training.

Effects of exercise on cardiovascular risk: mechanistic aspects

Physical activity is benefical acting on the following mechanisms: glucose metabolism, weight reduction, hemostatic/inflammatory markers, sympathetic nervous system, endothelial function/oxidative stress among others.

Clinical evaluation

Diagnosis of arterial hypertension:
- Diagnosis of arterial hypertension in adults is made when blood pressure is ≥140/90 mmHg on separate occasions.
- In children and adolescents age-adjusted tables based upon height percentiles and gender are recommended.
- White coat hypertension should be excluded, using 24-h monitoring if necessary.
Screening for secondary causes:
- It should be performed as usual.
- The use of medications and performance-enhancing drugs should be carefully excluded.
Stratification of cardiovascular risk:
- Stratification of cardiovascular risk is based on the following factors: blood pressure values, cardiovascular risk factors and established CV disease, target organ damage (e.g., attention to false positives: exercise-induced proteinuria and athlete's heart), exercise testing and cardiac ultrasound in all sports practitioners.
Establish sport eligibility:
- Sport eligibility is based on stratification of cardiovascular risk and sports categories, following international recommendations.

Treatment

Nonpharmacological approach, with lifestyle measures and avoidance of hypertension-inducing drugs, is always recommended.
Antihypertensive drugs should be chosen on the basis of concomitant cardiovascular risk factors and other comorbidities as usual.
Peculiarities of antihypertensive treatment in athletes should also be considered: diuretics and β-blockers are considered doping substances in certain sports and have a negative impact on sports performance; their use should be limited to selected cases.