Dobutamine for Aortic Stenosis

No longer useful?

Throughout the years, the adoption of Dobutamine stress in patients with aortic stenosis (AS) D2 stage was paramount to assess the correct diagnosis by differentiating between true aortic stenosis and pseudo-AS. It also estimates the prognosis, since those who had a contractile reserve with infusion of low doses of dobutamine showed, in the cohort studies in the 1990s and 2000s, a better long-term survival.

Recent studies have demonstrated that dobutamine test and the evidence of the presence of contractile reserve has not had a prognostic impact in this group of patients with the current interventionist treatment. Some questions come up:

  1. Currently, cohort studies include patients who undergo TAVR, a much less invasive procedure and this could positively influence survival, even for those who do not have contractile reserve. However, by doing sub-analyses of such studies, we see there is also an improvement in the results of patients who underwent conventional surgery.
  2. Perhaps, the “stroke volume” increment is limited in the face of severe fixed afterload (this exam was originally created to evaluate ischemic myocardiopathy – no high afterload involved) and does not reach values over 20%, leading, for this reason, and not due to a severe deficit in systolic function, to the absence of contractile reserve in the current used parameters. Thus, we ended up classifying some patients as absent, even though their myocardia are healthy. That could explain why some patients regarded as not having contractile reserve show drastic improvement in systolic function after reducing the afterload with the procedure.

There are still patients who would show a 20% increase in stroke volume, but they could not reach demanded levels so they could be classified as true AS (mean gradient > 40mmHg).

Recent publications have suggested that in this scenario, the estimate of the aortic AV should be applied in case of transvalvular flow normalization (250mL/sec).

This tool has shown a better diagnostic effect for patients with AS as well as a better prognostic estimate of survival compared to the simple analysis of contractile reserve.

Another aspect that demands attention is the fact that patients who would have low systolic dysfunction. For instance, around 40-50% of LVEF and already at rest would have flow values close to 250mL/sec. Dobutamine infusion could lead to a supra- physiological condition which generates high gradients in VA > 1cm 2 . In this case, the assessment should begin with aortic valve calcium score.

Will dobutamine retire in this investigation? In view of what has been demonstrated, patients who have reduced EF, mean gradient < 40 mmHg and VA < 1.0 cm 2 can be submitted to stress echo. If the result is the presence of viability and gradients elevation (i.e. true AS), surgery is indicated. If viability is present and VA increases, with a gradient <40 mmHg, there should be a clinical follow-up (pseudo- stenosis), or B stage. Patients who possess contractile reserve, but no greater than 40 mmHg whilst maintaining a low VA, we ought to calculate the estimated VA, then make decisions after the VA evaluation. In the absence of contractile reserve, we should proceed with the assessment of the aortic valve calcium score, the same goes occurs for those patients with flow rate close to 250mL/sec or presenting a contraindication to the dobutamine test.

Soon enough, dobutamine may not be present in future guidelines and calcium score may lead the role.

Suggested literature:

  1. Sato K, Sankaramangalam K, Kandregula K, et al. Contemporary Outcomes in Low-Gradient Aortic Stenosis Patients Who Underwent Dobutamine Stress Echocardiography. J Am Heart Assoc. 2019 Mar 19;8(6):e011168.
  2. Annabi MS, Touboul E, Dahou A, et al. Dobutamine Stress Echocardiography for Management of Low-Flow, Low-Gradient Aortic Stenosis. J Am Coll Cardiol. 2018 Feb 6;71(5):475-485.
  3. Annabi MS, Clavel MA, Pibarot P. Dobutamine Stress Echocardiography in Low-Flow, Low-Gradient Aortic Stenosis: Flow Reserve Does Not Matter Anymore. J Am Heart Assoc. 2019 Mar 19;8(6):e012212.

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