Limitations de l'étude

La taille de la population, bien que la plus importante décrite à ce jour pour ce type de patients, peut avoir limité notre capacité à détecter une association significative avec d'autres facteurs de risque et ne permet pas également la réalisation d'une analyse multivariée pour la mortalité à 30 jours dans le sous-groupe de patients subissant un RVA.

Compte tenu de la forte colinéarité entre la DLG de repos et le stress, il n'était pas possible d'inclure les deux paramètres dans les mêmes modèles multivariés. Toutefois, lorsqu’on utilise le même sous-groupe de patients et le même ajustement pour l'analyse multivariée, le χ² du modèle multivarié pour la prédiction de la mortalité toutes-causes était significativement meilleur avec la DLG de stress qu'avec la DLG de repos.

La mesure de la DLG n'était pas disponibles dans une proportion substantielle des patients recrutés dans l'étude TOPAS. Cependant, les caractéristiques de base ainsi que les taux de mortalité étaient similaires chez les patients avec et ceux sans DLG disponible. Ainsi, il est peu probable que cette limitation peut avoir introduit un biais de sélection. En outre, c’est la plus grande étude qui rapporte des données relatives à la DLG dans la SABD avec basse FEVG. De plus, dans le cadre de cette étude multicentrique, la mesure de la DLG a été effectuée dans un laboratoire centralisé d’échocardiographie pour minimiser la variabilité inter-sites.

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Conclusion et perspectives

Dans cette série prospective de patients avec SABD et basse FEVG, la DLG était un prédicteur indépendant de mortalité toutes-causes, en particulier chez les patients avec un traitement conservateur. Les résultats de cette étude suggèrent que la DLG peut être utile pour prédire la mortalité opératoire chez les patients subissant un RVA ainsi que le risque de mortalité à court et à long terme chez les patients traités de façon conservative. Enfin, la DLG mesurée lors d’une ESD peut apporter une valeur pronostique additionnelle au-delà de la DLG mesurée au repos. D'autres études sont nécessaires pour déterminer si le RVA par TAVI devrait être préféré au RVA chirurgical chez les patients avec une DLG fortement abaissée au repos et / ou pendant l’ESD.

À cet égard, il serait tout à fait intéressant de pouvoir comparer différentes stratégies de RVA chez des patients ayant une SABD et FEVG diminué et une DLG fortement abaissée et donc à très haut risque de décès, dans le cadre d’un essai clinique randomisé ou à défaut un registre multicentrique. Dans cette perspective, un registre multicentrique axé sur le traitement de ces patients par TAVI a été mis en place par les Drs Pibarot et Rodés-Cabau. Il s’agit du registre TOPAS-TAVI.

Par ailleurs, au cours de ce travail, nous avons également étudié la déformation longitudinale de la paroi libre du ventricule doit dans cette population et les résultats préliminaires semblent très prometteurs quant à la stratification du risque au-delà des paramètres échocardiographiques (fonction VG et autres) utilisés actuellement. Nous poursuivons actuellement les travaux sur la fonction ventriculaire droite et sa valeur pronostique.

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