Current ESC guidelines do not include trans-stenosis pressure gradient among the pro-intervention parameters [1]; indications for repair are a non-invasive pressure difference > 20 mmHg between upper and lower limbs or hypertension associated with a ≥ 50% narrowing relative to the reference aortic diameter (diaphragm level). Our patient did not match either the arterial pressure or the anatomic criteria, thus was correctly not addressed to surgical repair of the CoA.
This case raises some interesting issues: the lack of uniformity among the international guidelines on this topic and the undefined role of co-morbidities (such as AR) in the severity assessment of the disease. According to current AHA guidelines patients with a peak-to-peak pressure gradient > 20 mmHg (as it was in our patient) satisfy the first criterion for interventional/surgical repair recommendation [2]. As a result to date a rigorous adherence to guidelines would make the same patient differently treated in Europe and North America.
For sure functional parameters (i.e. invasive pressure gradient) have the advantage to reflect the real pathophysiological effect of an anatomical anomaly; nevertheless they are rather difficult to be interpreted. In our case, for example, the co-presence of severe AR can be easily misleading. No guidelines help physicians in this task. In our patient it is reasonable to hypothesize that severe AR increases the pre-load and the related stroke volume (SV); this raise pushes the trans-CoA pressure gradient to higher levels than those expected in relation to the anatomic narrowing. Conversely the reduced Ejection Fraction decreases the SV causing an opposite effect on pressure gradient and making its interpretation and the decision-making process more complex.
Moreover also strictly anatomical parameters can be misleading: the relative narrowing of the isthmic aorta (compared to diaphragmatic diameter) can be biased by an extensive aortic disease, mainly in older patients. Thus Takeda recently proposed a novel “cross sectional area” cut-off indexed to the patients’ body surface as a possible alternative indicator of CoA severity [3]. Anyway, in the presented case, even when indexed to our patient’s body surface (2.1 m2), anatomical parameters did not reach threshold for intervention indication.
These considerations suggest the need for an accurate “case by case” evaluation. In the reported case anatomical data and patient’s age at symptoms presentation support the conclusion of a “non severe” CoA despite the pressure gradient degree (probably influenced by AR). This case would better match the recently proposed “aortic pseudocoarctation” definition, usually characterized by lower increase of the LV after-load (as compared to “true CoA”) and milder pathophysiological effects such as the absence of collateral circulation [4].