[Left ventricular contractile reserve in asymptomatic patients with primary mitral regurgitation]

This study aimed to quantify left ventricular contractile reserve (LVCR) and to evaluate its usefulness for risk stratification in asymptomatic patients with primary mitral regurgitation (MR). Resting and exercise echocardiography including two-dimensional speckle tracking was performed in 115 consecutive asymptomatic patients with moderate to severe primary MR. LCVR was defined as an exercise-induced increase in LV ejection fraction ≥ 4% or in LV global longitudinal strain ≥ 2%. LVCR was absent in approximately one half of the population. This absence was a strong independent predictor of cardiac events when assessed by exercise-induced changes in LV longitudinal function, but not when measured by exercise-induced changes in LV ejection fraction.

Impact of global hemodynamic load on exercise capacity in aortic stenosis

BACKGROUND

The determinants of maximal exercise capacity (MEC) in aortic stenosis (AS) are, in large part, unknown. We hypothesized that the left ventricular (LV) global hemodynamic load--as assessed by the valvulo-arterial impedance (Zva)--is one of the main determinants of MEC and we sought to evaluate the factors associated with reduced MEC in AS.

METHOD AND RESULTS

Asymptomatic patients with moderate or severe AS (n=62, aortic valve area <1.5 cm(2), 65 ± 13 years, 68% men) and preserved LV systolic function (ejection fraction>50%) were prospectively referred for comprehensive resting echocardiography and cardiopulmonary exercise test. Absolute peak VO2 was 19.5 ± 5.7 mL/kg/min (median 19.6 mL/kg/min; range 7.2-33.1 mL/kg/min). There were significant correlations between peak VO2 and: age, body mass index, LV stroke volumes, cardiac output, mean flow rate, mitral annulus s' and e' wave velocities, E/e' ratio and left atrial diameter (all p<0.05). Indexed mean flow rate and Zva were the strongest univariable echocardiographic determinants of peak VO2 (r=0.44, p<0.001 and r=-0.39, p=0.002, respectively). In addition, patients with reduced MEC (peak VO2<median) had higher Zva than those with preserved MEC (4.24 ± 1.18 vs. 3.71 ± 0.68 mmHg/mL/m(2), p=0.036). In multivariable analysis, age (p<0.001) and Zva (p=0.048) were the only independent predictors (r(2)=0.40) of peak VO2.

CONCLUSION

In asymptomatic patients with moderate to severe AS, MEC varies widely among patients, and is often lower than expected. Global LV hemodynamic load is the main echocardiographic determinant of reduced MEC in these patients, suggesting its usefulness for their clinical evaluation and management.

Childhood-onset chylomicronaemia with reduced plasma lipoprotein lipase activity and mass: identification of a novel GPIHBP1 mutation

OBJECTIVES

Deficiency in the catabolism of triglyceride-rich lipoproteins is the main cause of childhood-onset chylomicronaemia syndrome. Missense mutations in lipoprotein lipase (LPL) or in proteins influencing LPL activity or stability have been shown to be critical determinants of chylomicronaemia syndrome. The main objective of this study was to assess the primary deficiency in five cases of childhood-onset chylomicronaemia syndrome.

SETTING

Lipid clinic at a university hospital,

SUBJECTS

Subjects presenting with severe hypertriglyceridaemia and chylomicronaemia syndrome in which reduced LPL activity and mass were observed.

INTERVENTIONS

Analysis of LPL and GPIHBP1 genes.

RESULTS

Amongst the five patients, one novel homozygous missense mutation (p.C68Y) in exon 3 of GPIHBP1 was identified. The other four patients were homozygous for the common LPL mutation p.G188E.

CONCLUSION

These findings provide further evidence that GPIHBP1 is involved in the catabolism of triglyceride-rich lipoproteins and plays a role in childhood-onset chylomicronaemia.

[Assessment and management of aortic stenosis]

Surgical aortic valve replacement is the sole validated treatment of aortic stenosis. The indications for surgery rely on risk/benefit ratio and on the official recommendations. A symptomatic patient with severe aortic stenosis should be submitted to surgery. The indication of valve replacement is more difficult in asymptomatic patients. The decision should integrate a combination of an exercise test and prognostic parameters associated with poor outcome. Most of them are obtained by Doppler echocardiography. Patients presenting with severe aortic stenosis and low transvalvular gradient constitute a subgroup of patients who require appropriate echocardiographic assessment to determine the potential benefit and risk of surgery. Transluminal aortic valve implantation is a new modality for patients at high surgical risk.

[How I explore: ventricular arrhythmias in athletes]

Documented ventricular tachyarrhythmias or related symptoms need meticulous cardiac investigations. The mechanism of ventricular arrhythmia must be defined. The prognosis is related to underlying cardiac electrical or structural disorders. In the absence of cardiovascular abnormalities, the prognosis is good. No disqualification to competitive activity is required in most cases. Assessment of the risk of sudden death remains a continuing challenge in athletes. This article reviews the diagnostic and therapeutic approaches of ventricular arrhythmias encountered in trained athletes.