Right ventricular dysfunction after coronary artery bypass grafting

Abstract Background Impaired right ventricular (RV) function is a frequent echocardiographic finding following coronary artery bypass grafting (CABG). It is subject of debate whether this finding reflects actual RV dysfunction with clinical impact, or rather limitations of the applied echocardiographic measurements. Purpose We aimed to investigate prevalence of RV dysfunction using currently available echocardiographic measurements, and self-reported physical capacity more than two years after CABG. Materials and methods This pre-specified cross-sectional substudy of the SWEDEGRAFT trial included patients scheduled for follow-up more than two years after elective CABG at our institution. The SWEDEGRAFT trial is an ongoing multicenter, randomized clinical trial comparing patency of saphenous vein grafts harvested with "no-touch" and open skeletonized technique. We prospectively assessed RV function with multivariable transthoracic echocardiography. Self-reported physical capacity was assessed using the three items for physical limitation of the Seattle Angina Questionnaire (SAQ-7) (3 denotes the worst and 15 the best possible physical capacity), as well as NYHA-class. Baseline and procedural data were retrieved from the SWEDEGRAFT trial. Preoperative echocardiographies were systematically reexamined. Results We enrolled 207 patients into our substudy at a median follow-up after CABG of 31.0 (range 24.2-39.9) months. RV function assessed by tricuspid annular plane systolic excursion (TAPSE) was significantly reduced compared to the preoperative assessment. In contrast, postoperative RV function as assessed by RV fractional area change (FAC) was preserved. Similarly, assessment of three-dimensional RV ejection fraction (3D-RVEF) indicated preserved RV function (mean 49.4 ± 6.3 %). Mean RV global longitudinal strain was -19.7 (±3.6), and mean RV free wall strain was -22.7 (±4.9). At follow-up, assessments of 3D-RVEF and strain modalities were obtainable in 51.7% and 72.4% of patients, respectively. Patient-reported functional capacity was excellent (median score 15, interquartile range 1.5). NYHA-class improved significantly (NYHA-class I preoperative 49.4% vs. postoperative 61.4%, p=0.032). Postoperative median pro-Brain Natiuretic Peptide levels were 163 (interquartile range 195) ng/L. Conclusion RV systolic function was preserved more than two years after CABG when assessed by RV FAC and 3D-RVEF despite significant reduction in TAPSE. These findings likely reflect the increased sphericity of the RV following opening the pericardium during surgery. Our study supports that measurements of longitudinal systolic parameters likely underestimate RV systolic function after CABG.