Exaggerated Blood Pressure Response During Exercise Is Associated with Pathological Remodelling in Veteran Athletes

Background: Endurance athletes often develop physiological left ventricular hypertrophy (LVH). However, certain athletes, particularly those who are older, may develop pathological remodelling in association with hypertension which can be particularly exacerbated during exercise.



Cardiovascular magnetic resonance (CMR) can distinguish between LVH due to increased myocyte mass and expansion of the extracellular compartment which may indicate pathological remodelling.



We aimed to assess the relationship of physical fitness and exercise blood pressure (BP) with the myocardial composition of veteran endurance athletes.

Methods: We prospectively recruited athletes (cyclists/triathletes) aged ≥ 40y who exercised for ≥ 6h/week for ≥ 10y. Exclusion criteria consisted of any pre-existing cardiovascular disease including arterial hypertension.



Participants underwent cardio-pulmonary exercise testing and CMR including cine imaging, native and post contrast T1 mapping (MOLLI) and late gadolinium enhancement (LGE). VO₂max was standardised by using % achieved predicted VO₂max (VO₂max/ VO₂max age-sex-weight predicted VO₂max). Extracellular volume (ECV) was calculated using standard methods and left ventricular mass indexed to body surface area (LVMI) calculated. From these, the myocardium was divided into intracellular mass (ICM) as 1-ECV x LVMI and extracellular mass (ECM) as ECV x LVMI.

Results: Two hundred and eight athletes were recruited (mean age 58.8 ± 7.3 years; 86.5% male). % achieved predicted VO₂max was 137.8 ± 18.5% and mean exercise systolic BP (SBP) was 211.6 ± 30.4mmHg (Table 1). 42.2 % of athletes had fibrosis, all in a non-ischaemic pattern.



On univariable linear regression, % achieved predicted VO₂max was significantly associated with LVMI (beta 0.15, P< 0.001) due to an increase in ICM (beta 0.15, P< 0.001) but not ECM (beta 0.0002, P=0.83) (Table 2).



Exercise systolic BP was not associated with LVMI (beta 0.04 , P=0.15) with no association with ICM (beta 0.01 , P=0.61) but was significantly associated with ECM (beta 0.03 , P< 0.001).

On logistic regression, the presence of non-ischaemic fibrosis was not associated with % achieved predicted VO₂max (odds ratio (OR) 1.00, P=0.78) or exercise SBP (OR 1.00, P=0.60) but was associated with increasing age (OR 1.08, P< 0.001).

Conclusion: In veteran athletes, increased physical fitness is associated with increased LV mass mediated via greater myocyte mass with no change in ECM - in keeping with physiological hypertrophy. However, greater systolic BP response to exercise is associated with an increase in ECM without affecting myocyte mass and overall LV mass. Therefore, increased extracellular mass may be a novel biomarker to distinguish physiological from pathological remodelling in veteran athletes with exercise-induced hypertension.

Table 1; Baseline Demographic, Exercise and CMR Variables

	n= 208
Baseline Characteristics
Age (years)	58.8 ± 7.3
Male (n)	180 (86.5%)
BMI (kg/m2)	24.2 ± 2.6
Resting HR (BPM)	53.1 ± 7.4
Systolic BP (mmHg)	118.8 ± 12.0
Diastolic BP (mmHg)	73.2 ± 7.4
Exercise History
Training Hours per Week	10.9 ± 3.3
Active Years	30.7 ± 15.2
Cardio-pulmonary Exercise Test
Maximum Heart Rate (BPM)	160.5 ± 15.0
Relative Power (W/kg)	4.3 ± 0.96
% achieved predicted VO2max	137.8 ± 18.5
Exercise Systolic BP (mmHg)	211.6 ± 30.4
Exercise Diastolic BP (mmHg)	95.1 ± 18.0*
Cardiovascular Magnetic Resonance
LVEDVi (ml/m2)	107.0 ± 15.3
LVEF (%)	57.3 ± 4.8
LVMi (g/m2)	66.8 ± 10.8
RVEDVi (ml/m2)	110.7 ± 18.0
RVEF (%)	53.2 ± 5.8
LAVi (ml/m2)	45.9 ± 12.7
Native T1 (ms)	1249 ± 40
ECV (%)	22.1 ± 2.5
ICM (g/m2)	51.7 ± 8.9
ECM (g/m2)	15.1 ± 2.7
Fibrosis (%)	119 (42.2%)
Fibrosis mass when present (g)	2.35 ± 1.98
T2 (ms)	41.1 ± 2.2

Table 2- Univariable Regression With Variables Significantly Associated With ICM and ECM

	ICM (beta, 95% CI)	P Value	ECM (beta, 95% CI)	P Value
BMI (kg/m2)	0.56 (-0.09 – 0.24)	0.02*	-0.05  (-0.20 – 0.10)	0.49
Resting HR (BPM)	-0.36  (-0.52 – -0.20)	< 0.001*	-0.12  (-0.17 – -0.07)	< 0.001*
Systolic BP (mmHg)	0.20 (0.10 – 0.30)	< 0.001*	0.03  (0.00 – 0.06)	0.049*
Diastolic BP (mmHg)	0.23 (0.07 – 0.40)	0.006*	-0.01  (-0.06 – 0.05)	0.86
Active Years	0.16 (0.08 – 0.24)	< 0.001*	0.02  (-0.01 – 0.04)	0.15
% achieved predicted VO2max	0.15 (0.09 – 0.21)	< 0.001*	0.002 (-0.02 – 0.02)	0.83
Exercise SBP (mmHg)	0.01 (-0.03 – 0.05)	0.61	0.03 (0.01 – 0.04)	< 0.001*
Exercise DBP (mmHg)	-0.04 (-0.11 – 0.03)	0.28	0.01 (-0.01 – 0.03)	0.50

Figure 1- Scatter Plot of Associations Between Fitness and Exercise Systolic BP with ICM and ECM