The Role of Multimodality Cardiac Imaging for the Assessment of Sports Eligibility in Patients with Bicuspid Aortic Valve

Abstract

Bicuspid aortic valve (BAV) cannot be considered an innocent finding, but it is not necessarily a life-threatening condition. Athletes with BAV should undergo a thorough staging of the valve anatomy, taking into consideration hemodynamic factors, as well as aortic diameters and looking for other associated significant cardiovascular anomalies by use of a multimodality cardiac imaging approach. Furthermore an accurate follow-up is mandatory with serial cardiological controls in those allowed to continue sports.

ANATOMY AND CLASSIFICATION

The bicuspid aortic valve (BAV) is the most common congenital cardiac malformation, affecting 0.5-2% of the general population.[1,2,3,4,5] Compared to the normally formed aortic valve, it features two unequally sized cusps (leaflets) with or without a raphe, generally located in the largest leaflet. The raphe is believed to correspond to the area of congenital fusion between two rudimentary cusps, may vary in extension along the leaflet, and it does not contain valvular tissue. Several anatomical classifications of the BAV have been proposed, based on the pattern of cusp fusion (s), presence of the raphe, and commissural orientation.[6,7] The most common form is characterized by fusion of the left coronary and right coronary cusps (type 1 BAV or RL-BAV), also referred to as anteroposterior at transthoracic echocardiography (TTE); the fusion of the right coronary and noncoronary cusps is called type 2 or atypical or RN-BAV (right-left orientation at TTE); and the rarest form is fusion of the left and noncoronary cusps (type 3 or LN-BAV). According to another nomenclature, the “type” indicates the number of fusions, so that type 0 is the “naturally bicuspid” valve with only two equally sized cusps and no raphe, type 1 is the more common BAV (subdivided into RL, RN, and LN), and type 2 corresponds to the unicuspid aortic valve, with two fusions/raphes [Figure 1].[1,2,3,4,5,6,7]

Figure 1.

Anatomic classification of bicuspid aortic valve (BAV). L = Left, R = Right, N = Noncoronary, lat = Lateral, ap = Anteroposterior

MORPHOGENESIS AND HEREDITY

The events that lead to bicuspid malformation during human valvulogenesis are not yet fully understood: Animal model studies have suggested that aberrations in different signaling pathways involving endothelial-to-mesenchymal transition, neural crest cell migration, and septation of the conotruncus may subtend the abovementioned different anatomical forms.[8] BAV is inherited as an autosomal dominant trait with incomplete penetrance and variable expressivity: Many clinical studies have reported an increased prevalence (about 9%) in the first degree relatives (FDRs) of subjects with BAV, with an inheritability of about 89%.[9,10,11,12] Therefore, the current American College of Cardiology (ACC)/American Heart Association (AHA) guidelines recommend echocardiographic screening in all FDRs of patients with BAV.[13]

COMPLICATIONS AND TREATMENT

BAV can be either isolated or associated with other congenital anomalies: Among patients with aortic coarctation, a BAV is found in 50-75% cases: The diagnosis of BAV in a patient with known coarctation is crucial, as it implies a relevant increase of the risk for aortic complications.[14,15,16] BAV can be also associated with hypoplastic left heart syndrome, Shone syndrome, Williams’ syndrome, and Turner syndrome with coarctation.[17,18,19,20,21] A wide spectrum of cardiovascular complications, occurring either in pediatric age or in the adult life, is associated with congenital BAV, including valvular (stenosis, regurgitation, and endocarditis) and vascular (aortic aneurysm, annuloaortic ectasia, and acute aortic dissection) complications; so that the BAV represents a socially important source of morbidity for the healthcare system. An estimation of the actual incidence of such cardiovascular complications has been object of a number of studies, often yielding different figures; depending on referral bias, study period, mean age of the patients, diagnostic accuracy, etc. By screening about 21,000 Italian military conscripts (mean age 18 ± 2 years), Nistri and coworkers identified 167 BAVs (0.8%), of which 48 (29%) were normofunctional; whereas, 110 (66%) were regurgitant (moderate-severe degree of regurgitation in 20 patients) and only nine (5%) were stenotic.[22] This is remarkably different from the high prevalence of aortic stenosis (AS) that is reported in surgical series (up to 75% of BAVs), in which the mean age of the patients is generally older. The BAV indeed accounts for more than 50% of the cases of AS requiring surgery in adult age, a percentage that increases when the younger ages are considered selectively.[23] In fact, AS reaches the severity criteria for surgical indication 5–10 years earlier than in subjects with tricuspid aortic valve (TAV). Studies of natural history have been issued in recent years, ultimately depicting the clinical course of BAV-associated disease in the general population, reducing the referral bias to a minimum: Both in a study from the Olmsted County (Minnesota)[24] and in another series from Toronto (Ontario);[25] a relatively high rate of surgical operation was found, but lethal events were rare and life expectancy was not different from the general age-matched population. The presence of a BAV is also associated with an aortopathy that places the patients at increased risk for aneurysm formation (generally at the level of the ascending aorta) and dissection (generally type A). A dilatation of the ascending aorta has been reported in percentages between 33 and 80% of BAV patients, again depending on patient age and type of referral: Given the high prevalence of BAV in the cardiac surgical patient population, the clinician is quite frequently faced with the dilemma whether to treat a concomitant nonsevere aortic dilatation in a patient with surgical indications for bicuspid valve disease.[26] In such a situation it has been recently demonstrated that different surgeons use to adopt different policies, often even deviating from the current guidelines, some with a more aggressive attitude than officially recommended, some more conservatively. The question of how to manage a moderately dilated ascending aorta in patients with BAV, with or without valve dysfunction, remains debated mainly because of the unresolved questions and persisting gaps in knowledge about the pathogenesis of the BAV aortopathy.[27] Aortic wall alterations observed with BAV, commonly included among those forms of aortic pathology defined as “medial degeneration”, have led several authors to theorize that a common genetic defect may affect both valve and aorta development. Nevertheless a responsible gene has never been identified and only negative studies have been issued when possible linkages have been investigated with mutations in supposedly involved loci. Opposed to the genetic theory, the “hemodynamic” theory has been supported by others, whereby the peculiar aortic wall fragility could be caused by undue mechanical burden on the aortic wall persisting since first moments in life even in the absence of (and before the development of) significant stenosis or regurgitation. It has been demonstrated that BAV anatomy yields flow derangements that are more than enough to cause abnormal aortic wall shear stress even in the absence of transvalvular gradients.[28] The dichotomy of the pathogenetic theories translates into the abovementioned inconsistencies between official guidelines and the policies of individual cardiac surgery centers. At present, indications are fundamentally based on dimensional criteria (aortic diameter, either in absolute terms or normalized to anthropometrics). However, the most recent literature has focused on the heterogeneity of BAV condition, especially in terms of risk of valve dysfunction and of aortic aneurysm or dissection: Some patients remain free from complications for their entire lifetime, others experience much worse natural histories.[29,30] In the face of this prognostic complexity, the diameter alone appears to be a limited criterion and the research on possible additional clinical, imaging-based risk markers, and biomarkers of BAV aortopathy severity is currently notably active.[27,31] A recently proposed theory suggests that the heterogeneity of anatomical forms of aortic dilatation that can be encountered in association with BAV may reflect an heterogeneity in terms of pathogenesis and prognosis, that is, the two main different anatomical forms of dilatation (or “aortic phenotypes”) might be subtended by different combinations of genetic defects and hemodynamic derangements. The “root phenotype”, accounting for 20% of aortic dilatations with BAV, mainly observed in young male patients with pure aortic regurgitation (AR) or normally functioning valve, is characterized by greater dilatation of the sinuses of Valsalva compared to the tubular ascending tract: This form has been found associated with faster growth of the aortic diameter over time, higher rates of postoperative aortic complications following simple aortic valve replacement, greater aortic diameters in the FDRs with TAV, and is supposed to be linked to a greater risk of aortic dissection.[32,33,34,35] The more common “ascending phenotype” has a more variable natural history, but generally is characterized by more indolent progression and lower risk of complications.[33]

EXERCISE PERFORMANCE IN PATIENTS WITH BAV

Athlete's heart: Cardiovascular adaptations and diagnostic findings

Long-term intensive physical training determines progressive cardiac changes, characterized by modifications in cavity diameters, wall thickness, and functional parameters; which represent the so-called athlete's heart.[36,37,38]

Standard color-Doppler echocardiography and, in selected cases, cardiac magnetic resonance (CMR) have been widely used in the analysis of the characteristics of the athlete's heart, becoming sometimes irreplaceable in the evaluation of top-level athletes. Furthermore, novel echocardiographic technologies, like Doppler myocardial imaging (DMI) and strain imaging have shown their usefulness also in athlete's heart description and understanding, mostly because of their ability to earlier detection of myocardial systolic and diastolic dysfunction.

Athlete's left heart

The echocardiographic analysis of the athlete's left ventricle has shown different forms of adaptation, according to genetic factors, age, and mostly to the type and the intensity of chronic training. Isotonic exercise such as in endurance sports is the most responsible for a predominant volume overload, inducing an increase in left ventricular (LV) mass and end-diastolic diameter (eccentric LV hypertrophy); while isometric exercise, such as in strength disciplines, is instead associated with an increase of LV mass and wall thickness (concentric LV hypertrophy).[36,37,38] However, the hypertrophy patterns often show mixed characteristics of eccentric or concentric hypertrophy depending to the type and level of the sports activity. Some reports and different studies in fact showed that 55% of the athletes had an increased LV end-diastolic diameter on echocardiography. Interestingly, about 15% of the endurance athletes demonstrated cavity diameters >60 mm, in presence of normal cardiac function, in contrast with the impairment of both diastolic and systolic indexes typical of dilated cardiomyopathy (DCM).[39] Similarly, the maximum thickness of the interventricular septum (IVS) was lower than 12 mm in most of the athletes, and only 2% of them had a wall thickness between 13 and 16 mm, obviously depending onage, gender, and race.[40] Interestingly, most of the adaptations induced by physical training seem to regress after temporary suspension of training of only few weeks. In only 20% of the cases, however, a persistence of the dilation in the LV end-diastolic diameter was noted.[41] Of note, in athletes abusing of anabolic steroids, the development of LV myocardial thickening does not seem to be reversible, even after discontinuation of the drug.[42,43] By standard Doppler analysis, one of the peculiar characteristics of the athlete's heart is the normality of both systolic and diastolic LV functional indexes. In particular, athlete's transmitral flow pattern demonstrates a “supernormal” aspect with an increased contribution of early-diastolic phase in baseline conditions (early wave/atrial wave (E/A) ratio >2). This is a difference of pathological from physiological hypertrophy. By DMI, the “supernormal” diastolic function of the athlete has been confirmed, with high early-diastolic myocardial velocity (Em), and increased Em/Am ratio of the basal IVS as well as of the lateral walls.[44,45] In recent years, some studies have analyzed athlete's LV hypertrophy also by strain imaging, finding no significant differences in both systolic and diastolic strain parameters compared with control subjects.[46,47,48] CMR can provide detailed anatomical and functional information in the assessment of athlete's heart and its differential diagnosis. From these images highly accurate and reproducible measurements of LV volumes, mass, ejection fraction, and stroke volumes can be derived.[49,50,51,52,53,54,55,56] In addition, the high resolution and image contrast allow the detection of localized areas of pathology and fibrosis, including the apex or the basal anteroseptal wall. Sport activities are also responsible of left atrial (LA) size remodeling.[57,58] LA enlargement is common in a lot of athletes, and this modification does not regress completely after cessation of athletic activity and may predispose athletes to an increased risk of subsequent atrial fibrillation.[59] Pelliccia et al., for the first time studied the prevalence and the clinical significance of LA enlargement in competitive athletes.[57] They reported a mild increase of LA diameter (≥40 mm) in 18% of athletes and a marked dilatation (≥45 mm) in 2%. Our group performed a longitudinal study that provided reference values for LA volume index, confirming a higher prevalence of LA volume index increase in athletes: Mild enlargement in 24.3% and moderate enlargement in 3.2%. The most powerful independent determinants of LA volume index were type and duration of training and LV end-diastolic volume.[58]

Athlete's right heart

Like all four chambers of the athlete's heart, the right atrium (RA) and right ventricle (RV) undergoes functional, structural, and electrical remodeling as a result of the hemodynamic challenges of intense exercise training.[60,61] Some research suggests that the hemodynamic stress of intense exercise is greater for the right heart and, as a result, remodeling is slightly more profound than the left heart. The clinical consequence of this is that the right heart of the athlete can become quite profoundly dilated which may present issues in differentiating healthy remodeling from pathologies such as left-to-right shunts, arrhythmogenic right ventricular cardiomyopathy (ARVC), and DCM. During exercise, however, pulmonary artery pressures and right ventricular after load increase disproportionately relative to the systemic circulation.[62,63] Instead, normally, the right ventricular mass is approximately one-fifth that of the LV, reflecting the fact that the load of the pulmonary circulation is markedly less at rest. As a result, right ventricular wall stress exceeds that of the LV making it more susceptible to acute injury during prolonged endurance exercise.[64,65,66,67,68] Endurance training, more than strength training, due enlargement of cavity dimensions and increases of wall thickness of the size of right atrium (RA) and RV.[69,70,71,72,73] The degree of remodeling is similar to that of the left heart, leading to the concept of ‘balanced remodeling’.[74,75] However, some recent work has suggested that regular exercise may be associated with greater relative remodeling of the RV as has been shown in large studies of nonathletes and in smaller studies of endurance athletes, possibly reflecting the slight excess in wall stress to which the RV is exposed.[76,77] In routine clinical practice, the slight differences in the relative remodeling of the RV and LV are minimal. Clinicians will be familiar with the appearance in athletes of a volume loaded RV with some degree of septal flattening, “pouching” of the RV free wall below the lateral tricuspid annulus, and a pseudoaneurysmal appearance of RV free wall either side of where the moderator band attaches. All these features are commonly seen in healthy endurance athletes and do not represent pathology. One of the challenges in clinical practice has been to accurately measure RV size due to the complex three-dimensional (3D) structure of this chamber and the use of CMR and 3D echocardiography may make this more practicable in the future. D’Andrea et al., have provided some important initial experience in what constitutes the range of RV volumes in healthy athletes using 3D echocardiography.[72]

BAV AND PHYSICAL EXERCISE

Physical activity is a well-known protective factor for a multitude of pathological conditions. For this reason, national and international health organizations promote regular physical training among younger as well as older people. In this way, young athletes are examined by sports physicians and, an increasing number of them who have BAV, which is often asymptomatic, are diagnosed. However, as BAV can be associated with AS and/or AR, as well as with primitive or secondary aortic dilation, sports physicians are strongly involved in the decision about their eligibility to participate in sports. There is growing awareness that many patients with BAVs have disorders of vascular connective tissue, involving loss of elastic tissue, that may result in aortic root dilatation even in the absence of hemodynamically significant AS or AR.[78,79] Indeed, patients are prone to develop dilatation of the aortic root (right–left fusion) or of the ascending aorta/aortic arch (right-noncoronary cusp fusion).[80,81] Actually, a well-documented link exists between hypertension and aortic dilation in subjects with a normal TAV.[82,83] On the other hand, a greater prevalence of hypertension than expected for age-matched populations has been reported among young subjects suffering from aortic dissection.[84] Therefore, a facilitating role of high blood pressure (BP) values on aortic enlargement, and possibly dissection, can be hypothesized in subjects with BAV. Longitudinal studies in subjects with BAV are limited to competitive athletes and they show slow progression in LV and ascending aortic diameters with regular training compared to those athletes with TAV.[85] However, no data is available on strict endurance training programs. Several studies carried out in patients without aortic valve malfunction have shown that various kinds of endurance training are able to improve the elastic properties of the aorta.[86,87,88,89,90] We performed a study about aortic root dimensions in elite athletes which demonstrated that diameters at all levels are significantly greater in strength-trained athletes.[91] Even though there is no definitive proof in patients with BAV, it could be argued that moderate endurance training should be promoted in patients with BAV after AS, AR, aortic aneurysm, and coarctation are ruled out.

ELIGIBILITY IN COMPETITIVE SPORTS

In order to take any decision about sports eligibility, sports physicians should perform an initial accurate staging of the BAV; taking into account hemodynamic factors, aortic complications, and associated significant cardiovascular anomalies. A strict follow-up, with serial cardiological controls, is mandatory. Since rapid valve deterioration and progressive severe aortic dilation have been documented; complete cardiological examinations, comprising at least electrocardiogram (ECG), bi-dimensional echocardiography (2DE) with color-Doppler analysis, ECG stress test, and, in selected cases, BP monitoring and 24-h Holter ECG monitoring, should be required every year in athletes allowed to continue sports, even in subjects with a ‘near normal’ or uncomplicated BAV.[92,93] Until the late 1970s, in the majority of cases, BAV was an occasional finding at surgical inspection or necropsy. With the advent of 2DE, an early in vivo diagnosis has become feasible and the current modern imaging techniques (i. e., magnetic resonance, computed tomography, etc.) allow the collection of novel useful data on thoracic aorta in subjects with BAV. Clinically, suspicion of BAV may arise due to the presence of an ejection click at the base of the heart that can be linked to a systolic and/or diastolic murmur. Familial history may be helpful since in an increasing number of cases this condition appears heritable.[9,10,12] ECG abnormalities, such as LV hypertrophy, atrial enlargement, and arrhythmias can be associated with a BAV, but are a specific.

Arterial pulse examination and BP measurement at rest and during exercise may be of use, in order to recognize hypertensive or hypotensive conditions due to associated cardiovascular anomalies, such as severe AS and/or insufficiency, or aortic coarctation. Nevertheless, unequivocal diagnosis of BAV can be made by the presence of only two cusps, clearly identified in systole and diastole on 2DE in the parasternal short-axis view, following precise criteria.[94,95] Once a BAV condition has been diagnosed, it is of paramount importance to assess the presence or absence and the entity of valvular obstruction/incompetence by means of color-Doppler analysis. Moreover, as patients with BAV, independently from associated cardiovascular abnormalities and/or complications, may exhibit dilation of the aorta, aortic diameters should be measured at different levels [Figures 2–6].[92,93]

Figure 2.

Transthoracic echocardiography in uncomplicated type 1 BAV. Aortic short-axis view (a), mild aortic regurgitation (b), normal ascending aorta diameters (c), and absence of significant aortic stenosis (d)

Figure 6.

Aortic magnetic resonance in type 1 BAV with complete (a) and uncomplete (b) raphe

Figure 3.

Transthoracic and transesophageal echocardiography in complicated type 1 BAV. Aortic short-axis view (a), parasternal long-axis view with ascending aorta aneurism (b), and three-dimensional reconstruction of aortic valve (c-d)

Figure 4.

Aortic computed tomography in complicated type 1 BAV. Aortic short-axis view (a), and long-axis (b) with ascending aorta aneurism

Figure 5.

Aortic magnetic resonance in uncomplicated type 1 BAV. Aortic short-axis view (a), and long-axis (b) with mild eccentric regurgitation jet

A good correlation, actually, exists between aortic calibers by 2 DE and those obtained by magnetic resonance imaging of the thoracic aorta.[96] Echocardiography is also useful to detect an anomalous origin of the coronary arteries origin, a condition which account for up to 20% of cases of sudden cardiac death (SCD) in young athletes.[97,98] Anatomical coronary abnormalities can imply a potential risk of coronary artery compression, especially following exercise. These consequences predispose to myocardial ischemia, syncope, or decompensated heart failure, and likely to account for most cases of SCD.

There are recommendations about sport eligibility for patients with BAV from the ACC Foundation (36^th Bethesda Conference-2004), European Association for Cardiovascular Prevention and Rehabilitation (Recommendations for physical activity, recreation sport, and exercise training in pediatric patients with congenital heart disease: A report from the Exercise, Basic & Translational Research Section of the European Association of Cardiovascular Prevention and Rehabilitation, the European Congenital Heart and Lung Exercise Group, and the Association for European Paediatric Cardiology-2011), and from the Italian Cardiological Guidelines for Sports Eligibility in Athletes with Heart Disease (COCIS 2009). They have some common aspects, but also some differences.

In order to formulate eligibility criteria; the assessment of a classification of sports, based on the cardiovascular engagement, appears to be crucial.

In the 36^th Bethesda Conference report, there is a classification of sports according to the type and intensity of exercise performed and also with regard to the danger of bodily injury from collision, as well as the consequences of syncope.[99] Exercise can be divided into two broad types: Dynamic (isotonic) and static (isometric). Dynamic exercise involves changes in muscle length and joint movement with rhythmic contractions that develop a relatively small intramuscular force; and static exercise involves development of a relatively large intramuscular force with little or no change in muscle length or joint movement. These two types of exercise should be thought of as the two opposite poles of a continuum, with most physical activities involving both static and dynamic components. A classification of sports relates individual competitive sports to the two general types of exercise: Dynamic and static.[100] Each sport is categorized by the level of intensity (low, medium, and high) of dynamic or static exercise generally required to perform that sport during competition. It also recognizes those sports that pose significant risk due to bodily collision, either because of the probability of hard impact between competitors or between a competitor and an object, projectile, or the ground; as well as the degree of risk to the athlete or others if a sudden syncopal event occurs. Thus, in terms of their dynamic and static demands, sports can be classified as IIIC (high static, high dynamic), IIB (moderate static, moderate dynamic), IA (low static, low dynamic), and so forth.

The recommendations of the ACC that follow are for patients with bicuspid valves and associated aortic root enlargement:

1. Patients with BAVs with no aortic root dilatation (less than 40 mm or the equivalent according to body surface area in children and adolescents) and no significant AS or AR may participate in all competitive sports.

2. Patients with BAVs and dilated aortic roots between 40 and 45 mm may participate in low and moderate static or low and moderate dynamic competitive sports (classes IA, IB, IIA, and IIB), but should avoid any sports in these categories that involve the potential for bodily collision or trauma.

3. Patients with BAVs and dilated aortic root greater than 45 mm can participate only in low-intensity competitive sports (class IA).

If such patients also have significant AS, AR, or Marfan syndrome; these recommendations should be considered in concert with those discussed in the same document for patients with these valvular disease or disorder of connective tissue.[100,101]

European Association for Cardiovascular Prevention and Rehabilitation document focuses on eligibility criteria for competitive sports and extends the recommendations to leisure sports, physical activity, and even exercise training programs; in order to promote physical activity and exercise, identifying circumstances for precautions and specific guidance, and counseling.[102]

The level of evidence and the strength of recommendation are weighed and grading according to predefined scale. All physical activities can be characterized according to their static (need for strength) and dynamic (need for endurance) components, as described in the American classification.

European guidelines provide these recommendations:

1. Patients with BAV can participate in all sport activities if AS, AR, aortic aneurysm, and coarctation are ruled out.

2. Strength training with a very high static component (i. e., weight lifting) enhances aortic stiffness and dilatation and should be avoided (Class IIa, level of evidence C).[103,104]

3. Patients with mild aortic dilatation must stay at close surveillance with at least yearly echocardiography as dilatation may become progressive with any kind of training.[85]

4. Patients with stable moderate aortic aneurysm (40-45 mm in adults and their equivalents in children) may participate in low static and low or moderate dynamic competitive sports, additionally excluding sports with body collision and trauma (Class IIa, level of evidence C).[105]

5. Patients with progressive or large aortic aneurysm (>45 mm in adults or equivalent in children) must be consulted individually. They must limit their sports activities to low static/low dynamic activities or in more severe cases referred to surgery (Class I, level of evidence C).

6. Interval training should be omitted and resistance training should be limited to low or moderate intensities involving small muscle groups separately (Class IIa, level of evidence C).

If AS or regurgitation is present, physical activities must be curtailed as suggested by the guidelines for the management of valvular heart disease.[106]

According to Italian Cardiological Guidelines for Sports Eligibility in Athletes with Heart Disease (COCIS 2009), the classification of sports activities, based on the engagement of the cardiovascular system, is based primarily on the behavior of some important parameters, such as heart rate (HR) and BP, and their integration with physiological parameters, in order to take into consideration three basic indicators: Peripheral resistance, cardiac output, and level of adrenergic stimulation [Table 1].[107]

Table 1.

Modified from Italian cardiological guidelines for sports eligibility in athletes with heart disease 2013 [107]

Group A: Neurogenic
Characterized mainly by increases in heart rate from minimum to moderate, due to emotional component	Bowls (Raffa and petanque), bowling, curling, skittles
	Golf
	Fishing (marine and inland waters)
	Shooting sports (archery, flying, archery, etc).
	Sport hunting
	Biliards sports
	Bridge, checkers, chess
Group B: Neurogenic
Characterized mainly by increases in heart rate from moderate to high (and minor cardic output and peripheral resistance)	aMotor recing (speed, rally, autocross, regularity, Slalom National Karting)
	aAviation
	Horse riding
	aParachuting
	bApnea diving, scuba diving, underwater photos, video diving, underwater shooting Sailing
Group C: Pressure
Characterized by heart rate increased to maximum, medium to high peripheral resistance, submaximal cardiac output	aAlpinism
	aFree climbing
	Athletics (sprint, throwing, jumping, heptathlonb, decathlonb)
	aBob, Luge, Steleton
	Body building
	Cycling (speed, keinin, downhill mountain biking, BMX)
	Artistic gymnastics
	aMotor racing (motocross, endura, trial)
	Synchronized swrnming
	Weightlifting
	aWater skiing
	aAlpine and cross-country skiing (slalom, giant Skiing, Super G, Downhill, Alpine Skiing, Cross-country speed, carving skis, grass skiing, snawboard, jump)
	Surfing
	Tug of war
Group D: High cardiovascular engagement
Dl: characterized by variable trend of HR, peripheral resistance, and cardiac output	Badminton
	Baseball
	Bawls (flight)
	Football, Futsal
	Canaeing polo
	bAmerican Football
	Rhythmic Gymnastics, Twirling
	aHockey on ice, on track, on field
	aWrestling, Judo, Karate, Taekwondo, Kendo, Wushu kung iu
	Basketball
	Handball
	aWater polo
	Handball
	Volleyball, Beach Volleyball
	Polo
	aBoxing, Kick boxing
	aRugby, aUnderwater Rugby
	Fencing
	Softball
	Squash
	Tambourine
	Tennis
	Table tennis
D2: characterized by regular increases in submaximal or maximum frequency and cardiac output, and reduced peripheral resistance	Track and fields (middle distance running, duing, running, marathon, ultramarathon, mountain running, cross-country)
	Biathlon
	aRawing, Olympic Canoeing, Rafting Canoeing
	aCycling (individual and team pursuit, points race, the American line, individual time trial, mountain bike cross-country, cross-cycling)
	Nordic Combined
	Sport Dancing
	Swimming
	Fin swimming
	Orienteering
	Ice skating, roller skating, figure skating and other specialty shapes
	Modem Pentathlon
	Cross-country sking
	Triathlon
	aWind surf

^aIntrinsic risk is considered, ^bTraumatic risk is considered.

The Italian document recommends that athletes without hemodynamically significant AS or with uncomplicated BAV are eligible for all competitive sports in the absence of the following:

1. LV hypertrophy and LV systolic or diastolic dysfunction.

2. Abnormally elevated systolic BP or ST-segment changes during maximal stress test electrocardiogram.

3. Significant arrhythmias either at rest or during exercise and/or 24-h Holter ECG monitoring, including one training session.

Athletes with hemodynamically significant AS (mean gradient >20 mmHg) should avoid competitive sports. Six months after successful balloon valvuloplasty or surgical correction (residual mean gradient <20 mmHg — no significant AR), competitive sports eligibility may be allowed in selected cases. However, the same exclusion criteria listed above for athletes without hemodynamically significant AS or with uncomplicated BAV should be applied.[108] The occurrence of residual defects after the Ross procedure (pulmonary autograft replacement of the aortic valve, with or without reimplantation of the coronary arteries, followed by pulmonary homograft insertion) is relatively common. A 6-month eligibility period for competitive sports activities of Groups A and B (horse riding and sailing) may be considered in athletes with normal cardiac chamber size and function, and RV to pulmonary artery peak systolic gradient less than 30 mmHg. Conversely, athletes with more than mild AR, ECG alterations, and/or arrhythmias during maximal stress test electrocardiogram or 24-h Holter ECG monitoring, including one training session, should be restricted from competitive sports.

CONCLUSIONS

BAV cannot be considered an innocent finding, but it is not necessarily a life-threatening condition. In Italy, where sports physicians are directly involved in deciding the eligibility for competitive sports, athletes with BAV should undergo a thorough staging of the valve anatomy, taking into consideration hemodynamic factors, as well as aortic diameters and looking for other associated significant cardiovascular anomalies. Furthermore an accurate follow-up is mandatory with serial cardiological controls in those allowed to continue sports. Antibiotic prophylaxis for endocarditis is also recommended, particularly in subjects engaged in contact sports which can create infected wounds, although European Society of Cardiology (ESC) guidelines on infective endocarditis donot recommend this preventive measure in patients with BAV.[108,109]