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Figure 1 (Left) Response of peak instantaneous systolic left ventricular outflow tract gradient in patients treated medically with disopyramide (Diso) without the requirement for invasive non-pharmacologic intervention (such as surgical septal myectomy, alcohol septal ablation, or dual-chamber pacing). Depicted are the outflow gradients of 62 patients who had serial echocardiographic assessments with continuous-wave Doppler. (Right) Patients who required invasive intervention because of inadequate relief of heart failure symptoms and persistent outflow gradients. Depicted are the outflow gradients of 33 patients who had serial echocardiographic assessments. All gradient measurements in this group were performed before intervention.