Wang et al. [1] elegantly summarise the value of strain imaging in patients with aortic stenosis. The management of patients with asymptomatic severe aortic stenosis (AS) also represents an important clinical dilemma. The reported risk of sudden death whilst adopting a 'watch and wait' policy for symptoms is relatively low (<1% per annum); however in real world clinical practice the close follow-up of patients in published series is often not adhered to [2]. Aortic valve replacement has been advocated as an intervention in these patients which may reduce long-term mortality. Interpretation of these studies requires caution as mortality for aortic valve replacement reported in this series is far lower than the overall 3-4% risk reported from the Society of Thoracic Surgeons (STS) database [2]. It is clear that a better means of risk stratification of patients with asymptomatic severe AS is required. In patients with asymptomatic severe AS a reduction in left ventricular ejection fraction <50% is associated with a poor prognosis. Indeed the European Society of Cardiology and European Association for Cardio-Thoracic Surgery guidelines grade this as a Class I indication for aortic valve replacement [3]. Left ventricular ejection fraction is an imperfect marker of left ventricular systolic function. Myocardial deformation (strain) is a more sensitive marker of contractile function. In a study of 79 patients with asymptomatic severe AS and preserved ejection fraction, a global longitudinal strain of <15% was an independent predictor of mortality adding incremental prognostic value to other markers of risk i.e aortic valve calcification, valvulo-arterial impedance and STS risk score [4]. Furthermore, reduced preoperative global longitudinal strain in patients with preserved ejection fraction has been shown to predict cardiac mortality and morbidity post aortic valve replacement [5].
In summary, myocardial deformation imaging is able to add incremental prognostic data for evaluation of patients with asymptomatic severe AS and preserved ejection fraction.
Conflict of interest: none declared.
References
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