In the paper published by de la Morena et al.,1 the authors state that “in patients with hypertrophic cardiomyopathy, left ventricular outflow tract obstruction and left atrial volume are the main predictors of exercise capacity. Exercise echocardiography is a better predictor of functional performance than at-rest echocardiography, although its predictive power is under 50%.” These findings provided valuable insights into the determinants of functional impairment in hypertrophic cardiomyopathy (HC) and support the potential value of exercise echocardiography in the clinical assessment of all patients with HC. We wish to congratulate the authors in their efforts to disseminate data on the value of exercise echocardiography in the study of patients with HC, and on their very important clarification regarding the mechanism of obstruction and the evaluation of functional capacity in their study with the determination of oxygen consumption.
The results that they obtained, as stated, have a predictive power of under 50% and this may be eventually attributed to not only the multiple factors that influence the functional capacity in this pathology, but also to the fact that the obstructive character of the HC patient has been underestimated. The authors evaluated the gradients only in the left lateral decubitus before and after exercise. As we have shown previously, the number of patients that are obstructive and the magnitude of obstruction are different when echocardiography is done during all forms of exercise,2 and if after exercise the patients are still maintained in an orthostatic position.3,4
The importance of upright evaluation during and particularly after exercise was recently underscored by Dimitrow and Cheng,5 and we continue to think that laying the patients supine after any type of exercise is meaningless from the clinical point of view because this doesn’t happen usually in real life.
Last, according to previous publications,2,3 upright evaluation before exercise detected some patients with obstruction, a fact that was not present or was not presented in this paper. The reduction of preload in the upright position is an important stimulus for inducing left ventricular outflow tract obstruction, not only in HC but also in other conditions.5,6
Tome Esteban,7 in an editorial referring to the present paper, also underscored the importance of the use of a protocol that maximizes the factors that provoke obstruction in HC patients.
We think that future guidelines of scientific societies should clearly recommend an uniform methodology to be employed by all groups that study and treat this class of patients with the purpose that a common language may be used by all study groups in the future.
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