“Polarizing” microplegia improves cardiac cycle efficiency after CABG for unstable angina

BackgroundMyocardial protection during coronary artery bypass grafting (CABG) for unstable angina (UA) still represents a major challenge, ought to the risk for further ischemia/reperfusion injury. Few studies investigate the biochemical, hemodynamic and echocardiographic results of microplegia (Mic) in UA.MethodsEighty UA-patients undergoing CABG were randomized to Mic (Mic-Group) or standard 4:1 blood Buckberg-cardioplegia (Buck-Group). Troponin-I and lactate were sampled from coronary sinus at reperfusion (T1), and from peripheral blood preoperatively (T0), at 6 (T2), 12 (T3) and 48 (T4) hours. Cardiac index (CI), indexed systemic vascular resistances (ISVR), Δp/Δt, cardiac cycle efficiency (CCE), and central venous pressure (CVP) were collected preoperatively (T0), and since Intensive Care Unit (ICU)-arrival (T1) to 24 h (T5). Echocardiographic E-wave (E), A-wave (A), E/A, peak early-diastolic TDI-mitral annular-velocity (Ea), and E/Ea investigated the diastolic function and Wall Motion Score Index (WMSI) the systolic function, preoperatively (T0) and at 96 h (T1).ResultsMic-Group showed lower troponin-I and lactate from coronary sinus (p = .0001 for both) and during the postoperative course (between-groups p = .001 and .0001, respectively). WMSI improved only after Mic (time-p = .001). Higher CI Δp/Δt and CCE (between-groups p = .0001), with comparable CVP and ISVR (p = N.S.) were detected after Mic. Diastolic function improved in both groups, but better after Mic (between-groups p = .003, .001, and .013 for E, E/A, and Ea, respectively). Mic resulted in lower transfusions (p = .006) and hospitalization (p = .002), and a trend towards lower need/duration of inotropes (p = .04 and p = .041, respectively), and ICU-stay (p = .015).ConclusionMicroplegia attenuates myocardial damage in UA, reduces transfusions, improves postoperative systo-diastolic function, and shortens hospitalization.