CardiomyopathyTiming and Significance of Exercise-Induced Left Ventricular Outflow Tract Pressure Gradients in Hypertrophic Cardiomyopathy
Section snippets
Methods
The study group included 74 patients with HC but without LV outflow tract obstruction at rest (basal outflow gradient <30 mm Hg). They were consecutively studied at our institution using exercise echocardiography (Table 1). The mean patient age was 45 ± 16 years, and 53 (72%) were men. Historically, most patients (n = 70, 95%) had no or only mild exertional symptoms (Table 1). The clinical diagnosis of HC was determined by the demonstration on the 2-dimensional echocardiogram of a hypertrophied
Results
Data were obtained for 74 patients with HC with a LV outflow gradient of <30 mm Hg at rest in the supine position and erect on a cycle ergometer (Table 1). Of the 74 patients, 24 (32%) attained >85% of their maximum predicated heart rate, and 50 (68%) achieved submaximum target heart rates and terminated the test because of fatigue (n = 40), and/or dyspnea (n = 26), and/or a systolic blood pressure decrease of >25 mm Hg during exercise (n = 4).
Of the 74 study patients, 30 (40%) developed
Discussion
To achieve an enhanced understanding of the pathophysiology of exercise-induced LV outflow obstruction in patients with HC, we devised the present study protocol according to a serial gradient assessment at each step of a symptom-limited upright bicycle exercise test. We found that this strategy provided important information not available using a single gradient measurement at peak exercise or in the immediate recovery period. With real-time monitoring of the LV outflow tract velocities during
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This work was supported by Ministero Istruzione Università e Ricerca (PRin), Rome, Italy, the European Union (STREP Project 241577 “BIG HEART,” Seventh European Framework Program), Brussels, Belgium, and the Hearst Foundations, New York, New York.