A new diagnostic algorithm for assessment of patients with single ventricle before a Fontan operation.

Objectives: Cardiac catheterization has a low diagnostic yield before a Fontan operation, and magnetic resonance imaging and computed tomography are reliable alternatives to invasive angiography. A new diagnostic algorithm to avoid cardiac catheterization in "low-risk" subjects before a Fontan operation is proposed. Methods: The proposed algorithm would identify "high-risk" subjects on the basis of risk factors on medical history, echocardiography, and noninvasive angiography. The efficacy of this algorithm in screening for subjects deemed to be inoperable after catheterization was evaluated retrospectively in 151 children. For this analysis, results of conventional angiography (assumed to be equivalent to noninvasive angiography) were used. Results: According to the algorithm, 95 (63%) of 151 subjects had no risk factors ("low risk") whereas 56 (37%) of 151 had 1 risk factor or more ("high risk"). Nine (6%) of 151 subjects were found to be inoperable after catheterization and all 9 were correctly classified as high risk by the algorithm. In the 135 of 151 subjects who underwent a Fontan operation, the algorithm predicted an adverse postoperative outcome with a sensitivity of 51% and specificity of 78%. However, this prediction was not improved by including elevated pulmonary artery pressure or ventricular filling pressure as additional risk factors. Conclusions: The proposed algorithm effectively screened for subjects who were deemed unsuitable for a Fontan procedure. In addition, omitting preoperative invasive hemodynamic assessment did not impair prediction of adverse postoperative outcomes. Prospective evaluation of such a noninvasive diagnostic strategy before the Fontan operation is warranted.