Incidence of ventricular arrhythmias after left ventricular reconstructive surgery

Abstract

h doi:10.1016/j.jtcvs.2006.08.088 recent article from O’Neill and coworkers published in the Journal in November 2005 reports that after left ventricular reconstruction (LVR) for ischemic cardiomyopathy, either akinetic or dyskinetic, patients might emain at risk for malignant ventricular arrhythmias and hence might benefit from prophylactic implantable cardioverter defibrillator (ICD). There are no clear uidelines regarding the necessity of early ICD implantation in patients undergoing VR because the most important trials addressing this issue excluded patients ithin 3 months (Madit II) after coronary artery bypass grafting surgery. The authors report a high residual incidence of inducible ventricular tachycardia VT) after surgical intervention (42%), and they conclude that either early ICD mplantation or predischarge electrophysiologic (EP) study for risk stratification is ndicated in patients submitted to LVR for ischemic dilated cardiomyopathy. Major limitations of that study are that (1) ventricular volumes are not measured efore and after, and (2) the EP study is performed only after surgical intervention, nd this negates the possibility of evaluating the effects of LVR on arrhythmias. The authors look at 217 patients who had LVR and divide them into 3 groups. roups 1 and 2 had an ICD implanted either before or after surgical intervention. hirty patients had ICDs in situ before the operation (group 1), and 74 patients had CD implantation after LVR (group 2); indications for postoperative ICD implanation were secondary prevention in 28 and primary prevention in 48 (positive EP tudy result). The authors then compare these 2 groups with another group of 116 atients who did not receive an ICD. Of these, 67 had EP studies (negative results n 65), and 46 did not undergo EP studies for some reason. Patients in group 1 are the sickest because they have the largest volumes, more requent need of concomitant mitral valve surgery, and the lowest proportion of oncomitant revascularization. Group 1 had the highest rate of events (progressive eart failure was the most frequent cause of death). Overall, the incidence of sudden eath was extremely low, with only 1 sudden death of 20 deaths, which occurred in patient who had ICD implantation before the operation. They compare mortality n the 3 groups and show that annualized mortality is significantly lower in groups (with an ICD implanted for primary or secondary prevention) and 3 (without CDs) with respect to group 1 (ICDs implanted before the operation). These groups re not comparable preoperatively, and we can presume that they are not comparable lso after surgical intervention, but the authors do not provide postoperative data. e know that 15 patients with ICDs, 6 in group 1 (20%) and 9 in group 2 (12%), ad appropriate ICD therapies, which saved their lives, according to the O’Neill nterpretation. Independent predictors of ICD firings were preoperative volumes and jection fraction (EF), and we can hypothesize that patients who received ICD herapy and those who had positive EP study results early after surgical intervention id not have an improvement in volumes and EF after LVR. Ventricular volume before and after surgical intervention is crucial for arrhythia development based on the following considerations. A large ventricular volume rings high wall stress and high stretch, and stretch is arrhythmogenic. In previous rticles we have clearly demonstrated that patients with ventricular arrhythmias spontaneous or inducible) have end-diastolic and end-systolic volumes significantly arger than those seen in noninducible patients and that patients who die at follow-up ave the largest ventricular volumes. The antiarrhythmic effect of LVR has been