Biphasic changes in left ventricular end-diastolic pressure during dynamicexercise in patients with nonobstructive hypertrophic cardiomyopathy

Objectives The aim of this study was to clarify the serial changes in left ventricular (LV) end-diastolic pressure (LVEDP) during dynamic exercise in patients with hypertrophic cardiomyopathy (HCM). Background Although HCM is characterized by impaired resting LV diastolic f unction, serial changes in LVEDP during exercise have not been characterize d. Methods We simultaneously measured LV pressure and LV dimensions during sym ptom-limited supine bicycle exercise in 5 healthy individuals and 20 patien ts with HCM. Exercise thallium-201 scintigraphic studies were also performe d. Results The LVEDP (baseline: 12 +/-5 mm Hg) progressively increased to a ma ximum value at peak exercise (28 +/-8 mm Hg) in 11 patients with HCM (group I). In the remaining nine patients with HCM (group II), changes in LVEDP d uring exercise were biphasic, with an initial progressive increase and a su bsequent gradual decline up to peak exercise (14 +/-4 mm Hg at baseline, 27 +/-5 mm Hg at the critical heart rate, 16 +/-3 mm Hg at peak exercise). Ex orcise-induced changes in LV dimensions and LV peak systolic pressures were similar in both groups. However, the maximum first derivative of LV pressu re was greater and the LV pressure half-time was shorter in group II than i n group I at a similar peak exercise heart rate. The biphasic changes in LV EDP disappeared by pretreatment with propranolol. The LV hypertrophy scores were higher in group I than in group II. Exercise thallium-201 images show ed more severe perfusion defects in group I than in group II patients. Conclusions The biphasic changes in LVEDP seen during exercise may be relat ed to improved coronary microcirculation in response to beta-adrenergic sti mulation in patients with mild to moderate HCM. (J Am Coll Cardiol 2001;38: 335-43) (C) 2001 by the American College of Cardiology.