The authors of the letter state that patient evaluation during exercise in an upright position may provide the most sensitive detection of latent obstruction in patients with hypertrophic cardiomyopathy. On the basis of this observation, they point out the possibility that our study1 may have underestimated the number of patients with obstructive forms. Their reasoning is based on 2 reports2,3 involving a small number of patients (17 and 37, respectively) who underwent submaximal tests. In these tests, the authors observed, in just 7 cases, that the obstruction was detectable only after exercise in an upright position and disappeared within a few seconds of changing to the supine position.

We carried out symptom-limited tests and prefer the decubitus position, since we evaluate diastolic flow and left ventricular outflow tract flow. Our method enables us to obtain 2-dimensional and Doppler images within a little over 1min after exercise. Knowing that the obstruction is fleeting, we always begin with color-guided continuous wave Doppler. In some cases, the obstruction may have disappeared; however, in the absence of sound comparative studies with maximum exercise tests that reveal the frequency of this event and time elapsed before it occurs, we consider it quite unlikely that an obstruction occurred in a significant number of our patients.

Nevertheless, and taking into account our results demonstrating that it is more important to determine the presence of obstruction than to quantify the degree,1 we have modified our protocol and, coinciding with the authors of the letter, we focus on evaluating the presence of obstruction at peak exercise and during the immediate postexercise period, maintaining the upright position.

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