Key role of left ventricular untwisting in endurance cyclists at onset of exercise

Exercise-induced changes in left ventricular strain are affected by interleukin-6 activity: An exploratory analysis of a randomised-controlled trial in humans with abdominal obesity

Whilst the exercise-induced myokine interleukin-6 (IL-6) plays a beneficial role in cardiac structural adaptations, its influence on exercise-induced functional cardiac outcomes remains unknown. We hypothesised that IL-6 activity is required for exercise-induced improvements in left ventricular global longitudinal strain (LV GLS). In an exploratory study 52 individuals with abdominal obesity were randomised to 12 weeks' high-intensity exercise or no exercise in combination with IL-6 receptor inhibition (IL-6i) or placebo. LV strain and volume measurements were assessed by cardiac magnetic resonance. Exercise improved LV GLS by -5.4% [95% CI: -9.1% to -1.6%] (P = 0.007). Comparing the change from baseline in LV GLS in the exercise + placebo group (-4.8% [95% CI: -7.4% to -2.2%]; P < 0.0004) to the exercise + IL-6i group (-1.1% [95% CI: -3.8% to 1.6%]; P = 0.42), the exercise + placebo group changed -3.7% [95% CI: -7.4% to -0.02%] (P = 0.049) more than the exercise + IL6i group. However, the interaction effect between exercise and IL-6i was insignificant (4.5% [95% CI: -0.8% to 9.9%]; P = 0.09). Similarly, the exercise + placebo group improved LV global circumferential strain by -3.1% [95% CI: -6.0% to -0.1%] (P = 0.04) more compared to the exercise + IL-6i group, yet we found an insignificant interaction between exercise and IL-6i (4.2% [95% CI: -1.8% to 10.3%]; P = 0.16). There was no effect of IL-6i on exercise-induced changes to volume rates. This study underscores the importance of IL-6 in improving LV GLS in individuals with abdominal obesity suggesting a role for IL-6 in cardiac functional exercise adaptations.

Adaptation of Left Ventricular Twist Mechanics in Exercise-Trained Children Is Only Evident after the Adolescent Growth Spurt

BACKGROUND

The extent of structural cardiac remodeling in response to endurance training is maturity dependent. In adults, this structural adaptation is often associated with the adaptation of left ventricular (LV) twist mechanics. For example, an increase in LV twist often follows an expansion in end-diastolic volume, whereas a reduction in twist may follow a thickening of the LV walls. While structural cardiac remodeling has been shown to be more prominent post-peak height velocity (PHV), it remains to be determined how this maturation-dependent structural remodeling influences LV twist. Therefore, we aimed to (1) compare LV twist mechanics between trained and untrained children pre- and post-PHV and (2) investigate how LV structural variables relate to LV twist mechanics pre- and post-PHV.

METHODS

Left ventricular function and morphology were assessed (echocardiography) in endurance-trained and untrained boys (n = 38 and n = 28, respectively) and girls (n = 39 and n = 34, respectively). Participants were categorized as either pre- or post-PHV using maturity offset to estimate somatic maturation.

RESULTS

Pre-PHV, there were no differences in LV twist or torsion between trained and untrained boys (twist: P = .630; torsion: P = .382) or girls (twist: P = .502; torsion: P = .316), and LV twist mechanics were not related with any LV structural variables (P > .05). Post-PHV, LV twist was lower in trained versus untrained boys (P = .004), with torsion lower in trained groups, irrespective of sex (boys: P < .001; girls: P = .017). Moreover, LV torsion was inversely related to LV mass (boys: r = -0.55, P = .001; girls: r = -0.46, P = .003) and end-diastolic volume (boys: r = -0.64, P < .001; girls: r = -0.36, P = .025) in both sexes.

CONCLUSIONS

A difference in LV twist mechanics between endurance-trained and untrained cohorts is only apparent post-PHV, where structural and functional remodeling were related.

Additive effects of type 2 diabetes and metabolic syndrome on left ventricular torsion and linear deformation abnormalities during dobutamine stress echocardiography

Objective

The interplay between metabolic syndrome (MS) and type 2 diabetes (T2D) on regional myocardial mechanics and the potential additional effects of their combination remain poorly understood. In this context, we evaluated left ventricular (LV) torsion and linear deformation at rest and under dobutamine (DB) stress in patients with T2D, MS or both.

Methods

Thirty-nine T2D patients without MS (T2D), 37 MS patients free from T2D (MS), 44 patients with both T2D and MS (T2D-MS group) and 38 healthy patients (control group) were prospectively recruited. Speckle-tracking echocardiography (STE) was conducted at rest and low dose DB to evaluate LV myocardial longitudinal (LS) as well as circumferential (CS) strain and early diastolic strain rate (LSrd, CSrd) and twist-untwist mechanics.

Results

At rest, MS, T2D and controls presented with similar resting LS and LSrd while significant lower values were obtained in T2D-MS compared to controls. DB revealed reduced LS, LSrd, CS and CSrd in MS and T2D groups compared to controls. In T2-MS, the decline in LS and LSrd established at rest was exacerbated under DB. Stress echocardiography revealed also lower basal rotation and subsequently lower twist in MS and T2D patients compared to controls. T2D-MS showed major impairments of apical rotation and twist under DB stress, with values significantly lower compared to the 3 other groups. From stepwise multiple linear regression analysis, epicardial adipose tissue for Δ (rest to DB) LS, numbers of MS factors for Δ CS and Δ Twist emerged as major independent predictors.

Conclusion

These results demonstrate synergic and additive effects of T2D and MS on LV torsion and linear deformation abnormalities in asymptomatic patients with metabolic diseases. They also highlight the usefulness of speckle tracking echocardiography under DB stress in detecting multidirectional myocardial mechanics impairments that can remain barely detectable at rest, such as in isolated T2D or MS patients.