Cardiac MRI in Athletes

Abstract

Cardiac magnetic resonance imaging (CMR) is often used in athletes to image cardiac anatomy and function and is increasingly requested in the context of screening for pathology that can cause sudden cardiac death (SCD). In this thesis, patterns of cardiac adaptation to sports are investigated with CMR. Chapter 2 describes our finding that left-right ratios are preserved across all sports categories, and that these ratios are similar to those found in non-athletic controls. The ratio of ventricular volume and wall mass is also similar across sports categories and non-athletic controls. Besides providing additional sports category-specific CMR reference values and upper limits for athletes, we also found that sports category is an important determinant of ventricular dimensions, irrespective of training hours, age and gender. Sports that involve dynamic (endurance) exercise are associated with larger volumes and wall mass, while the largest values are found in combined high dynamic-high static (strength-endurance) sports. Purely high static (strength) sports do not result in significant increases of ventricular volume and wall mass. Previous studies by others that reported selectively increased wall mass in strength-trained athletes may have been confounded by the concealed use of anabolic androgenic steroids (AAS) amongst their populations. A comparison of AAS-using strength athletes with non-AAS-using strength athletes in chapter 3 shows a significant association between AAS use and larger ventricular dimensions, in combination with impaired diastolic and systolic ventricular function. In chapter 4 we found that athletes of black ethnicity have significantly more pronounced ventricular hypertrabeculation, resembling left ventricular non-compaction (LVNC). Ethnicity proved to be an important determinant of hypertrabeculation, which in turn was associated with reduced ejection fraction. As the increased trabeculation is probably benign and physiological, it is important to be aware of this to prevent confusion of LVNC with increased hypertrabeculation as seen in black athletes. The relatively preserved volume-to-mass and left-to-right ratios are investigated further in chapter 5 and chapter 6, as a tool to differentiate physiological cardiac adaptation from hypertrophic cardiomyopathy (HCM) and arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), respectively. In HCM a predominant increase in ventricular wall mass is observed and the volume-to-mass ratio is effective at differentiating between patients and controls. ARVC/D is associated with a disproportionately large right ventricle. The current diagnostic criteria make use of absolute RV cut-off values and could be improved upon by also considering the left-to-right ventricular volume ratio. This would help to prevent false positive findings, especially in athletes. In conclusion, this thesis adds to current basic knowledge on physiological cardiac changes in athletes and also provides possible differentiating parameters for clinical use