The late prognosis after localized resection for fixed (discrete and tunnel) left ventricular outflow tract obstruction.

We studied the follow-up status of 56 patients after operation for fixed left ventricular outflow tract obstruction (LVOTO), 42 with discrete LVOTO consisting of an obstructing membranous ring in the left ventricular outflow tract (LVOT) and 14 with tunnel (diffuse) LVOTO. Forty-one of the 56 patients were available for long-term follow-up. Patients with discrete LVOTO fared better than patients with tunnel LVOTO postoperatively in their functional class status (discrete: 21 in Class I, five in Class II; tunnel: one in Class I, four in Class II; p less than 0.05), their LVOT peak systolic gradients (discrete: 22 +/- 4 mm Hg; tunnel: 98 +/- 23 mm Hg; p less than 0.02), their actuarially determined survival probabilities (discrete: 82% +/- 9% at 20 years; tunnel: 40% +/- 19% at 20 years; p less than 0.1), and their survival probabilities without an adverse event, i.e., (1) death, (2) reoperation, (3) residual gradient greater than 50 mm Hg, (4) significant aortic regurgitation, (5) bacterial endocarditis, or (6) complete heart block (discrete: 43% +/- 9% at 4 years, 36% +/- 9% at 10 years, and 15% +/- 9% at 20 years; tunnel: 0% at 4 years; p less than 0.02). Thus most patients who undergo operation for fixed LVOTO will survive late postoperatively; resection of the membrane is adequate for relief of LVOTO and for relief of symptoms in most patients with discrete LVOTO; the majority of patients with tunnel LVOTO who undergo only local resection will have an unsatisfactory operative result; most patients with discrete as well as tunnel LVOTO surviving operation will have clinically significant adverse events early or late postoperatively. This last observation dictates continuing long-term follow-up evaluations of patients operated upon for fixed LVOTO.