Jason O. Robertson

Concomitant tricuspid valve surgery during implantation of continuous-flow left ventricular assist devices: A Society of Thoracic Surgeons database analysis

BACKGROUND Performing concomitant tricuspid valve procedures (TVPs) in left ventricular assist device (LVAD) patients with significant pre-operative tricuspid regurgitation (TR) is controversial, and no studies have been large enough to definitively guide therapy. METHODS Between January 2006 and September 2012, 2,196 patients with moderate to severe pre-operative TR from 115 institutions underwent implantation of a continuous-flow left ventricular assist device (LVAD) as reported by The Society of Thoracic Surgeons National Database. Of these, 588 (27%) underwent a concomitant TVP. Inverse probability weighting based on propensity score was used to adjust for differences between the LVAD alone and LVAD+TVP groups, and outcomes were compared. RESULTS Most patients in the LVAD+TVP group underwent an annuloplasty alone (81.1%). Concomitant TVP did not affect risk of post-operative right VAD insertion (risk ratio [RR], 0.81; 95% confidence interval [CI], 0.49-1.36; p = 0.4310) or death (RR, 0.95; 95% CI, 0.68-1.33; p = 0.7658). However, TVP was associated with an increased risk for post-operative renal failure (RR, 1.53; 95% CI, 1.13-2.08; p = 0.0061), dialysis (RR, 1.49; 95% CI, 1.03-2.15; p = 0.0339), reoperation (RR, 1.24; 95% CI, 1.07-1.45; p = 0.0056), greater total transfusion requirement (RR, 1.03; 95% CI, 1.01-1.05; p = 0.0013), and hospital length of stay > 21 days (RR, 1.29; 95% CI, 1.16-1.43; p < 0.0001). Time on the ventilator and intensive care unit length of stay were also significantly prolonged for the LVAD+TVP group. CONCLUSIONS Performing a concomitant TVP for continuous-flow LVAD patients with moderate to severe TR did not reduce early death or right VAD requirement and was associated with worse early post-operative outcomes. These data caution against routine concomitant TVP based solely on degree of pre-operative TR and suggest that additional selection criteria are needed to identify those patients in whom concomitant TVP may prevent post-operative right ventricular failure.

Predictors and Risk of Pacemaker Implantation After the Cox-Maze IV Procedure

BACKGROUND The incidence of and causes for permanent pacemaker implantation (PPM) after surgical arrhythmia procedures remain poorly understood because of the varied lesion patterns and energy sources reported in small series. This study characterized the incidence, indications, and risk factors for PPM after the Cox-maze IV (CMIV) procedure when performed as either a lone or a concomitant procedure. METHODS A retrospective analysis of 340 patients undergoing a CMIV as either a lone (n = 112) or a concomitant (n = 228) procedure was conducted. The incidence, indication, and variables associated with PPM implantation within 1 year of the operation were assessed. Follow-up was conducted at 30 days and 1 year and was 90% complete. RESULTS The incidence of PPM after a lone CMIV procedure was 5%. Patients with concomitant cardiac operations had a nonsignificant increase in PPM insertion at 30 days (11% vs 5%, p = 0.14) and 1 year (15% vs 6%, p = 0.06) when compared with lone CMIV patients. Of patients who required pacemakers, sinus node dysfunction was present in 79% (35/44) of patients in the entire series and in 88% (8/9) after lone CMIV. After PPM, 84% (37/44) of patients remained paced at last follow-up. Multivariate analysis identified age (odds ratio = 1.10 [1.06-1.14], p < 0.001) as the only variable associated with higher risk of a PPM after any CMIV procedure. CONCLUSIONS The risk of PPM implantation after a lone CMIV is 5% and increases with age. The need for a PPM after a CMIV is largely due to SA node dysfunction, which appears unlikely to recover. These data should help physicians counsel patients regarding the perioperative risks associated with the CMIV.

The impact of CHADS2 score on late stroke after the Cox maze procedure

OBJECTIVE The Heart Rhythm Society, European Heart Rhythm Association, and European Cardiac Arrhythmia Society jointly recommend indefinite warfarin anticoagulation in patients with CHADS2 (congestive heart failure, hypertension, age, diabetes, and stroke) score of at least 2 who have undergone ablation for atrial fibrillation. This study determined the impact of CHADS2 score on risk of late stroke or transient ischemic attack after the performance of a surgical Cox maze procedure. METHODS A retrospective review of 433 patients who underwent a Cox maze procedure at our institution was conducted. Three months after surgery, warfarin was discontinued regardless of CHADS2 score if the patient showed no evidence of atrial fibrillation, was off antiarrhythmic medications, and had no other indication for anticoagulation. A follow-up questionnaire was used to determine whether any neurologic event had occurred since surgery. RESULTS Follow-up was obtained for 90% of the study group (389/433) at a mean of 6.6 ± 5.0 years. Among these patients, 32% (125/389) had a CHADS2 score of at least 2, of whom only 40% (51/125) remained on long-term warfarin after surgery. Six patients had late neurologic events (annualized risk of 0.2%). Neither CHADS2 score nor warfarin anticoagulation was significantly associated with the occurrence of late neurologic events. Among the individual CHADS2 criteria, both diabetes mellitus and previous stroke or transient ischemic attack were predictive of late neurologic events. CONCLUSIONS The risk of stroke or transient ischemic attack in patients after a surgical Cox maze procedure was low and not associated with CHADS2 score or warfarin use. Given the known risks of warfarin, we recommend discontinuation of anticoagulation 3 months after the procedure if the patient has no evidence of atrial fibrillation, has discontinued antiarrhythmic medications, and is without any other indication for systemic anticoagulation.

The CURE-AF trial: a prospective, multicenter trial of irrigated radiofrequency ablation for the treatment of persistent atrial fibrillation during concomitant cardiac surgery.

BACKGROUND Ablation technology has been introduced to replace the surgical incisions of the Cox-Maze procedure in order to simplify the operation. However, the efficacy of these ablation devices has not been prospectively evaluated. OBJECTIVE The purpose of this study was to examine the efficacy and safety of irrigated unipolar and bipolar radiofrequency ablation for the treatment of persistent and long-standing persistent atrial fibrillation (AF) during concomitant cardiac surgical procedures. METHODS Between May 2007 and July 2011, 150 consecutive patients were enrolled at 15 U.S. centers. Patients were followed for 6 to 9 months, at which time a 24-hour Holter recording and echocardiogram were obtained. Recurrent AF was defined as any atrial tachyarrhythmia (ATA) lasting over 30 seconds on the Holter monitor. The safety end-point was the percent of patients who suffered a major adverse event within 30 days of surgery. All patients underwent a biatrial Cox-Maze lesion set. RESULTS Operative mortality was 4%, and there were 4 (3%) 30-day major adverse events. Overall freedom from ATAs was 66%, with 53% of patients free from ATAs and also off antiarrhythmic drugs at 6 to 9 months. Increased left atrial diameter, shorter total ablation time, and an increasing number of concomitant procedures were associated with recurrent AF (P <.05). CONCLUSION Irrigated radiofrequency ablation for treatment of AF during cardiac surgery was associated with a low complication rate. No device-related complications occurred. The Cox-Maze lesion set was effective at restoring sinus rhythm and had higher success rates in patients with smaller left atrial diameters and longer ablation times.

Deficiency of LRP8 in mice is associated with altered platelet function and prolonged time for in vivo thrombosis

INTRODUCTION Our group has previously reported genetic studies associating polymorphisms in the low density lipoprotein receptor related protein 8 (LRP8) gene with myocardial infarction. The aim of this study was to define the role of platelet surface LRP8 in thrombosis. MATERIALS AND METHODS Flow cytometry, aggregometry, intravital microscopy and tail bleeding assays were used to examine platelet function and hemostasis in LRP8-deficient mice and littermate controls. RESULTS We demonstrated that activation of platelets from both LRP8(+/-) and LRP8(-/-) mice was reduced in vitro in response to either ADP or thrombin. In vivo, LRP8-hemizygous and LRP8(-/-) mice demonstrated 200% and 68% increased time for carotid occlusion in response to FeCl(3) injury, respectively. Moreover, lipidated apoE3, a ligand for LRP8, inhibited platelet activation in a dose-dependent fashion. This inhibition was markedly attenuated in LRP8(-/-) but not LRP8(+/-) mice and did not result from membrane cholesterol efflux or a nitric oxide dependent pathway. Tail bleeding times were unaffected in both genotypes. CONCLUSIONS Our results suggest that LRP8 is capable of altering thrombosis without affecting normal hemostasis through mechanisms both dependent on and independent of apoE. This suggests a means whereby clot formation could be affected in humans with LRP8 gene variants.

Concomitant aortic valve procedures in patients undergoing implantation of continuous-flow left ventricular assist devices: An INTERMACS database analysis

BACKGROUND Management of existing aortic insufficiency (AI) and mechanical aortic valves in patients undergoing left ventricular assist device (LVAD) implantation remains controversial. Surgical options to address these issues include closure, repair or replacement of the valve. METHODS Continuous-flow LVAD/biventricular VAD patients entered into the INTERMACS database between June 2006 and December 2012 were included (n = 5,344) in this analysis. Outcomes were compared between patients who underwent aortic valve (AV) closure (n = 125), repair (n = 95) and replacement (n = 85). RESULTS Among patients who underwent an AV procedure, actuarial survival was significantly reduced for AV closures (63.2%) compared with AV repairs (76.8%) and replacements (71.8%) (p = 0.0003). Differences were greater between groups when only INTERMACS Level 1 or 2 patients were analyzed (p = 0.003). After multivariate adjustment, AV closure remained a significant risk factor for mortality (hazard ratio = 1.87, 95% confidence interval 1.39 to 2.53, p < 0.0001). At 6 to 12 months post-operatively, moderate to severe AI developed in 19%, 5%, 9% and 10% of patients with available echocardiography who underwent repair, closure, replacement and no intervention, respectively (p < 0.0001). Competing outcomes demonstrate that, at 1-year, fewer patients with AV closures were transplanted compared with patients with repairs/replacements (14% vs 19%). No differences were observed between groups with respect to cause of death, re-hospitalization, right heart failure or stroke. CONCLUSIONS AV closure was associated with increased mortality when compared with repair or replacement in patients with AI who underwent LVAD insertion. The reasons for this association require further investigation. This is the largest study to date to examine concomitant AV procedures in patients undergoing LVAD insertion.

Beating Heart Cardioscopy: A Platform for Real-Time, Intracardiac Imaging

PURPOSE The purpose of this study was to develop a method for real-time, fiberoptic, intracardiac imaging to serve as a platform for closed-chest, intracardiac surgery on the beating heart. DESCRIPTION Fiberoptic cardioscopy of the left and right heart was conducted in a porcine model. A cardiopulmonary bypass circuit maintained systemic organ perfusion and a separate circuit replaced intracardiac blood with oxygenated, modified Krebs-Henseleit perfusate. EVALUATION Video images of structures in the left and right sides of an in vivo beating heart were obtained, including the inner surface of the left and right atria and ventricles, the mitral and aortic valves, the Thebesian veins, and the coronary sinus. Effective isolation of the heart from systemic and intracardiac blood flow and control of perfusion rates were important factors for successful image acquisition. CONCLUSIONS Fiberoptic cardioscopy is a novel approach that allows for visualization of the structures within a nonarrested heart on bypass. It lays the groundwork for a platform that could lead to more successful percutaneous valvular and intracardiac procedures in a stable hemodynamic environment.

One hundred days or more bridged on a ventricular assist device and effects on outcomes following heart transplantation

BACKGROUND Successful bridging to transplantation (BTT) with ventricular assist devices (VAD) is an alternative to mitigate the effects of end-stage heart failure on organ function while awaiting a heart. The effects of long-term VAD BTT on patient outcomes following transplantation are poorly studied. METHODS A retrospective chart review identified 145 patients BTT with a VAD between November of 1996 and June of 2005 at the Cleveland Clinic. Patients were divided into two groups and outcomes were compared: group 1 was supported for <100 days (median=44 days) and group 2 was supported for > or =100 days (median=161 days). RESULTS Patients in group 1 were less likely to be blood type O (33% vs 68%, p<0.0001). BTT <100 days trended towards independently predicting improved survival by multivariate proportional hazards analysis (risk ratio=0.75, 95% CI=0.52-1.08, p=0.12), largely due to reduced in-hospital mortality in this group (2% vs 11%, p=0.055); however, no significant difference with respect to long-term survival was observed by Kaplan-Meier analysis (p=0.14). Furthermore, causes of death differed between groups: group 1 more commonly died of coronary artery vasculopathy (26% vs 0%, p=0.022) and group 2 more commonly died of sepsis (60% vs 26%, p=0.026). Ultimately, 21% of all group 2 patients died from sepsis (compared to 7% of group 1 patients, p=0.018). CONCLUSIONS This study suggests that prolonged BTT with a VAD is a viable treatment strategy but may lead to significantly more post-transplant deaths from sepsis and higher in-hospital mortality. These data may inform management of this high-risk patient population.

How I do it: Minimally invasive Cox-Maze IV procedure

Our patient is a 66-year-old female with a 2-year history of atrial fibrillation (AF) and mitral valve prolapse who presented with dyspnea on exertion. She was found to be in AF upon her admission electrocardiogram. A transthoracic echocardiogram was performed demonstrating moderateto-severe mitral regurgitation (MR) with a left atrial (LA) diameter of 5.1 cm and normal left ventricular (LV) function. After completion of her workup, it was decided that the patient would best be treated by a minimally invasive Cox-Maze IV (CMIV) and concomitant mitral valve procedure given her significant MR and symptoms. This article and accompanying video will discuss how the minimally invasive CMIV procedure is performed. Surgical techniques Preparation In order to perform a mini-thoracotomy mitral valve maze procedure, the patient is positioned with the right chest elevated 45° and the hips flat. Transesophageal echocardiography (TEE) is performed to assess the MR, and examine for a patent foramen ovale or clot in the LA appendage. The aortic valve is also evaluated since significant aortic insufficiency is a contraindication to this approach. The patient is prepped and draped in the usual fashion.

Quantification of the functional consequences of atrial fibrillation and surgical ablation on the left atrium using cardiac magnetic resonance imaging.

OBJECTIVES The effect of atrial fibrillation (AF) on left atrial (LA) function has not been well defined and has been largely based on limited echocardiographic evaluation. This study examined the effect of AF and a subsequent Cox-Maze IV (CMIV) procedure on atrial function. METHODS Cardiac magnetic resonance imaging (cMRI) was performed in 20 healthy volunteers, 8 patients with paroxysmal atrial fibrillation (PAF) and 7 patients with persistent or long-standing persistent atrial fibrillation (LSP AF). Six of the PAF patients underwent surgical ablation with the CMIV procedure and 5 underwent both pre- and postoperative cMRIs. The persistent or LSP AF patients underwent only postoperative cMRIs because all scans were performed with patients in normal sinus rhythm. Volume-time curves throughout the cardiac cycle and regional wall shortening were evaluated using the cine images and compared across groups. RESULTS Compared with normal volunteers, patients with PAF had significantly decreased reservoir contribution to left ventricular (LV) filling (P = 0.0010), an increased conduit function contribution (P = 0.04) and preserved booster pump function (P = 0.14). Following the CMIV procedure, significant reductions were noted with respect to reservoir and booster pump function, with corresponding increases in conduit function. These differences were more drastic in patients with persistent/LSP AF. Regional wall motion was significantly reduced by PAF in all wall segments (P < 0.05), but was not further reduced by the CMIV. Despite changes in LA function, LV function was preserved following surgery. CONCLUSIONS PAF significantly altered LA function and has a detrimental effect on regional wall motion. Surgical intervention further altered LA function, but the reasons for this are likely multifactorial and not entirely related to the lesion set itself.