Myocardial perfusion and function of the systemic right ventricle in patients after atrial switch procedure for complete transposition: long-term follow-up.

OBJECTIVES: Our purpose was to assess the right ventricular (RV) function and identify patients with RV impairment long after the Mustard or Senning operation.
BACKGROUND: Systemic ventricular failure can cause myocardial perfusion abnormalities in thallium scintigraphy correlating with hemodynamic deterioration.
METHODS: Myocardial perfusion at rest and at peak exercise was assessed in 61 patients, aged 7 to 23 years in mean time 10.0 +/- 2.9 years after surgery using technetium-99m methoxyisobutyl isonitrile single-photon emission computed tomography. Ventricular function was assessed by first-pass radionuclide angiography at rest. Exercise capacity was determined with a modified Bruce protocol.
RESULTS: The mean RV ejection fraction was 36.1 +/- 7.7%, and left ventricular (LV) ejection fraction was 52.1 +/- 9.4%. Moderate or severe perfusion abnormalities on the rest scan were observed in 20 patients (33%). On exercise perfusion worsened in another 13 patients (21.3%). Patients with perfusion defects on stress scan had significantly lower RV and LV ejection fraction (33.2 vs. 39.4%; p = 0.002 and 49.2 vs. 55.5%; p = 0.01, respectively). They were also older (16.6 vs. 13.0 years; p = 0.002), operated on at an older age (4.0 vs. 2.4 years; p = 0.05) and had longer follow-up (12.5 vs. 10.5 years; p = 0.003).
CONCLUSIONS: Myocardial perfusion defects are common findings in patients in long-term follow-up after atrial switch operation. Despite excellent exercise tolerance, the extent of myocardial perfusion abnormalities correlated well with impaired RV and LV function, and greater perfusion defects were seen more frequently in older patients with longer follow-up. It is likely that myocardial perfusion defects could be a sensitive predictor of systemic ventricular impairment.