Hypertrophic Cardiomyopathy Comparison of Dual-Chamber Pacing Versus Septal Myectomy for the Treatment of Patients With Hypertrophic Obstructive Cardiomyopathy A Comparison of Objective Hemodynamic and Exercise End Points

RESULTS Baseline symptom status, left ventricular outflow tract gradients, exercise times and maximal oxygen consumption peak were similar between the two groups. Left ventricular outflow gradient was reduced from 76 6 57 to 9 6 17 mm Hg (p 5 0.0001) after myectomy, and from 77 6 61 to 55 6 39 mm Hg (p 5 0.07) after pacing (p 5 0.02 for comparison with myectomy). Ninety percent of myectomy patients experienced symptomatic improvement as compared with 47% in the pacing group. Exercise duration increased significantly from 6.6 6 2.8 to 8.7 6 3.0 min (p 5 0.0003) after myectomy compared with a change from 6.4 6 2.1 to 7.0 6 2.2 min (p 5 NS) in the pacing group. Maximal oxygen consumption increased from 19.4 6 6.4 to 22.2 6 6.5 ml/kg/min after myectomy (p 5 0.004), whereas the pacing group did not experience any significant change (19.6 6 6.5 vs. 20.1 6 6.5 ml/kg/min, p 5 NS).