Exercise intolerance in patients with congenitally corrected transposition of the great arteries relates to right ventricular filling pressures.

Background: Patients with congenitally corrected transposition of the great arteries (ccTGA) have significantly reduced exercise tolerance. Progressive right ventricular (RV) dysfunction with tricuspid regurgitation (TR) and other haemodynamic lesions are common among them. We hypothesised that interaction of these factors may result in increased systemic RV filling pressure, which in turn impact on exercise capacity.
Methods: Patients with ccTGA in functional class I or II, able to perform treadmill exercise and without resting cyanosis were enrolled. All patients underwent cardiopulmonary exercise testing and transthoracic echocardiographic examination. RV filling pressure was estimated using tissue Doppler imaging (TDI) techniques by measuring early annular diastolic velocity (Ea) and the ratio of the transtricuspid inflow to the early annular diastolic velocity (E/Ea).
Results: A total of 27 patients (mean age 41 years, 48% female) were assessed, the majority (63%) asymptomatic. Many patients had coexistent haemodynamic lesions including shunts, pulmonary stenosis, TR and systemic ventricular dysfunction. Average percentage predicted peak oxygen consumption, VE/VCO(2) slope and heart rate reserve were abnormal in this population. Patients with moderately/severely impaired exercise capacity (≤ 60% predicted peak VO(2)) had significantly higher E/Ea ratios compared to those with normal/mildly impaired exercise capacity (septal E/Ea = 17.1 ± 9.7 vs 8.8 ± 1.6 and lateral E/Ea = 11.5 ± 5.8 vs 6.6 ± 1.3, p = 0.007 and 0.01 respectively).
Conclusion: Reduced exercise capacity is common in adults with ccTGA even among asymptomatic patients and relates to increased RV filling pressures assessed by TDI. This index could potentially be used to optimize therapy or prognosticate adverse events in ccTGA patients.
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