Michael E. Bowdish

Rate Control versus Rhythm Control for Atrial Fibrillation after Cardiac Surgery.

BACKGROUND Atrial fibrillation after cardiac surgery is associated with increased rates of death, complications, and hospitalizations. In patients with postoperative atrial fibrillation who are in stable condition, the best initial treatment strategy--heart-rate control or rhythm control--remains controversial. METHODS Patients with new-onset postoperative atrial fibrillation were randomly assigned to undergo either rate control or rhythm control. The primary end point was the total number of days of hospitalization within 60 days after randomization, as assessed by the Wilcoxon rank-sum test. RESULTS Postoperative atrial fibrillation occurred in 695 of the 2109 patients (33.0%) who were enrolled preoperatively; of these patients, 523 underwent randomization. The total numbers of hospital days in the rate-control group and the rhythm-control group were similar (median, 5.1 days and 5.0 days, respectively; P=0.76). There were no significant between-group differences in the rates of death (P=0.64) or overall serious adverse events (24.8 per 100 patient-months in the rate-control group and 26.4 per 100 patient-months in the rhythm-control group, P=0.61), including thromboembolic and bleeding events. About 25% of the patients in each group deviated from the assigned therapy, mainly because of drug ineffectiveness (in the rate-control group) or amiodarone side effects or adverse drug reactions (in the rhythm-control group). At 60 days, 93.8% of the patients in the rate-control group and 97.9% of those in the rhythm-control group had had a stable heart rhythm without atrial fibrillation for the previous 30 days (P=0.02), and 84.2% and 86.9%, respectively, had been free from atrial fibrillation from discharge to 60 days (P=0.41). CONCLUSIONS Strategies for rate control and rhythm control to treat postoperative atrial fibrillation were associated with equal numbers of days of hospitalization, similar complication rates, and similarly low rates of persistent atrial fibrillation 60 days after onset. Neither treatment strategy showed a net clinical advantage over the other. (Funded by the National Institutes of Health and the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT02132767.).

A Decade of Living Lobar Lung Transplantation: Perioperative Complications after 253 Donor Lobectomies†

Living lobar lung transplantation places two donors at risk for each recipient. We examined the perioperative outcomes associated with the 253 donor lobectomies performed at our institution during our first decade of living lobar lung transplantation. There have been no perioperative or long‐term deaths. 80.2% of donors (n = 203) had no perioperative complications, while fifty (19.8%) had one or more complication. The incidence of intraoperative complications was 3.6%. Complications requiring reoperation occurred in 3.2% of donors. 15.0% of donors had other perioperative complications; the most serious were two donors who developed pulmonary artery thrombosis, while the most common was the need for an additional thoracostomy tube or a thoracostomy tube for ≥14 d for persistent air leaks and/or drainage. Right‐sided donors were more likely to have a perioperative complication than left‐sided donors (odd ratio 2.02, p = 0.04), probably secondary to right lower and middle lobe anatomy. This experience has shown donor lobectomy to be associated with a relatively low morbidity and no mortality, and is important if this procedure is to be considered an option at more pulmonary transplant centers, given continued organ shortages and differences in philosophical and ethical acceptance of live

Surrogate markers and risk factors for chronic lung allograft dysfunction.

Obliterative bronchiolitis (OB) is the histologic correlate of chronic allograft dysfunction in pulmonary transplantation. The histologic diagnosis of OB is challenging, therefore a physiologic definition, bronchiolitis obliterans syndrome (BOS) based on pulmonary function tests has been used as a surrogate marker for OB for the last decade. BOS has proven to be the best available surrogate marker for OB and is predictive of the ultimate endpoints of graft and patient survival. Multiple other clinical markers have been reported and proposed as alternates for or complements to BOS grade, but all need further evaluation and validation in large, prospective clinical trials. Lastly, given the early occurrence and high incidence of chronic allograft dysfunction, the easily measurable endpoint of BOS grade, and our lack of understanding of ways to prevent or alter the course of BOS, lung transplant recipients represent an ideal population for clinical trials targeting prevention and treatment of chronic allograft dysfunction.

Ventricular Tachycardia in the Era of Ventricular Assist Devices

Ventricular Tachycardia in the Era of Ventricular Assist Devices.  Sustained ventricular tachycardia (VT) in patients with advanced cardiomyopathy is a potentially life‐threatening arrhythmia. Newer treatment strategies have evolved that combine the use of catheter ablation to target the substrate for VT and ventricular assist devices (VADs) to hemodynamically support the failing ventricle. This editorial is targeted to the practicing clinician caring for these difficult patients. The current article reviews the use of percutaneous VADs to support catheter ablation of VT, the use of durable VADs to support the failing heart in patients with recurrent VT, ventricular arrhythmias in patients with durable VADs, and the use of catheter ablation to treat VT in patients with durable VADs. (J Cardiovasc Electrophysiol, Vol. 22, pp. 359‐363, March 2011)

Evidence for recipient derived fibroblast recruitment and activation during the development of chronic cardiac allograft rejection.

Background. Allograft fibrosis is a prominent feature of chronic rejection. Although intragraft fibroblasts contribute to this process, their origin and exact role remain poorly understood. Methods. Using a rat model of chronic rejection, LEW to F344, cardiac fibroblasts were isolated at the point of rejection and examined in a collagen gel contraction assay to measure fibroblast activation. The allograft microenvironment was examined using immunohistochemistry for fibrogenic markers (transforming growth factor [TGF]-&bgr;, platelet-derived growth factor [PDGF], tissue plasminogen activator [TPA], plasminogen activator inhibitor [PAI]-1, matrix metalloproteinase [MMP]-2, and tissue inhibitor of matrix metalloproteinase [TIMP]-2). The origin of intragraft fibroblasts was studied using female to male allografts followed by polymerase chain reaction [PCR] and in situ hybridization for the male sry gene. Results. The cardiac fibroblasts isolated from allografts with chronic rejection exhibited higher gel contractibility (50.9% ± 6.1% and 68.2% ± 3.8% at 4 and 24 hr) compared with naive cardiac fibroblasts (30.7% ± 3.5% and 55.3% ± 6.6% at 4 and 24 hr; P <0.05 and <0.05, respectively). Immunostaining for TGF-&bgr;, PDGF, TPA, PAI-1, MMP-2 and TIMP-2 was observed in all allografts at the time of rejection. In situ hybridization demonstrated the presence of sry positive cells in female allografts rejected by male recipients. Sixty-five percent of fibroblast colonies (55 of 85) isolated from female heart allografts expressed the male sry gene. Conclusion. Cardiac fibroblasts are activated and exist in a profibrogenic microenvironment in allografts undergoing chronic rejection. A substantial proportion of intragraft fibroblasts are recruited from allograft recipients in this experimental model of chronic cardiac allograft rejection.

A comparison of aortic valve replacement via an anterior right minithoracotomy with standard sternotomy: a propensity score analysis of 492 patients

OBJECTIVES Right anterior minithoracotomy with central arterial cannulation is our preferred technique of minimally invasive aortic valve replacement (AVR). We compared perioperative outcomes with this technique to those via sternotomy. METHODS Between March 1999 and December 2013, 492 patients underwent isolated AVR via either sternotomy (SAVR, n = 198) or minimally invasive right anterior thoracotomy (MIAVR, n = 294) in our institution. Univariate comparisons between groups were made to evaluate overall outcomes and adverse events. To control treatment selection bias, propensity scores were constructed from core patient characteristics. A propensity score-stratified analysis of outcome and adverse events was then performed. RESULTS Overall mortality was 2.5 and 1.0% in the SAVR and MIAVR groups, respectively. Hospital and ICU stays were shorter, there was less intraoperative blood product usage, and fewer wound infections in the MIAVR group. There were no differences in other adverse events, including strokes. The composite end-point of alive and adverse event-free was significantly more common in the MIAVR group (83 vs 74%, P = 0.002). After adjusting for the propensity score, hospital and ICU stays remained shorter and intraoperative blood product usage remained less in the MIAVR group. There was no difference in mortality, stroke or other adverse events between groups. CONCLUSION Minimally invasive AVR via an anterior right thoracotomy with predominately central cannulation can be performed with morbidity and mortality similar to that of a sternotomy approach. There appear to be advantages to this minimally invasive approach when compared with sternotomy in terms of less intraoperative blood product usage, lower wound infection rates and decreased hospital stays. If mortality and the occurrence of adverse events are taken together, MIAVR may be associated with better outcomes. As minimally invasive AVR becomes more common, further long-term follow-up is needed and a prospective multicentre randomized trial would be warranted.

Modified Bentall operation with bioprosthetic valved conduit: Columbia University experience.

A conduit was made by sewing a bovine pericardial valve into a graft conduit with the pseudo-sinuses of Valsalva. The graft collar below the valve cuff ring was sewn to the aortic annulus with interrupted pledgeted sutures. From August 2005 to February 2008, 68 patients underwent aortic root replacements with this technique. Operative mortality was 2.9% (2 acute aortic dissection patients died). During median follow-up of 11 months, 1 patient had reoperation for conduit failure due to infectious endocarditis. This technique is safe and feasible with favorable early outcomes. Because the valve is sewn above the outflow tract, superior hemodynamics are achieved. Reoperation may be accomplished by removal of the valve rather than full root re-replacement.

Effect of Cerebral Embolic Protection Devices on CNS Infarction in Surgical Aortic Valve Replacement: A Randomized Clinical Trial.

Importance Stroke is a major complication of surgical aortic valve replacement (SAVR). Objective To determine the efficacy and adverse effects of cerebral embolic protection devices in reducing ischemic central nervous system (CNS) injury during SAVR. Design, Setting, and Participants A randomized clinical trial of patients with calcific aortic stenosis undergoing SAVR at 18 North American centers between March 2015 and July 2016. The end of follow-up was December 2016. Interventions Use of 1 of 2 cerebral embolic protection devices (n = 118 for suction-based extraction and n = 133 for intra-aortic filtration device) vs a standard aortic cannula (control; n = 132) at the time of SAVR. Main Outcomes and Measures The primary end point was freedom from clinical or radiographic CNS infarction at 7 days (± 3 days) after the procedure. Secondary end points included a composite of mortality, clinical ischemic stroke, and acute kidney injury within 30 days after surgery; delirium; mortality; serious adverse events; and neurocognition. Results Among 383 randomized patients (mean age, 73.9 years; 38.4% women; 368 [96.1%] completed the trial), the rate of freedom from CNS infarction at 7 days was 32.0% with suction-based extraction vs 33.3% with control (between-group difference, −1.3%; 95% CI, −13.8% to 11.2%) and 25.6% with intra-aortic filtration vs 32.4% with control (between-group difference, −6.9%; 95% CI, −17.9% to 4.2%). The 30-day composite end point was not significantly different between suction-based extraction and control (21.4% vs 24.2%, respectively; between-group difference, −2.8% [95% CI, −13.5% to 7.9%]) nor between intra-aortic filtration and control (33.3% vs 23.7%; between-group difference, 9.7% [95% CI, −1.2% to 20.5%]). There were no significant differences in mortality (3.4% for suction-based extraction vs 1.7% for control; and 2.3% for intra-aortic filtration vs 1.5% for control) or clinical stroke (5.1% for suction-based extraction vs 5.8% for control; and 8.3% for intra-aortic filtration vs 6.1% for control). Delirium at postoperative day 7 was 6.3% for suction-based extraction vs 15.3% for control (between-group difference, −9.1%; 95% CI, −17.1% to −1.0%) and 8.1% for intra-aortic filtration vs 15.6% for control (between-group difference, −7.4%; 95% CI, −15.5% to 0.6%). Mortality and overall serious adverse events at 90 days were not significantly different across groups. Patients in the intra-aortic filtration group vs patients in the control group experienced significantly more acute kidney injury events (14 vs 4, respectively; P = .02) and cardiac arrhythmias (57 vs 30; P = .004). Conclusions and Relevance Among patients undergoing SAVR, cerebral embolic protection devices compared with a standard aortic cannula did not significantly reduce the risk of CNS infarction at 7 days. Potential benefits for reduction in delirium, cognition, and symptomatic stroke merit larger trials with longer follow-up. Trial Registration clinicaltrials.gov Identifier: NCT02389894

Impact of Left Ventricular to Mitral Valve Ring Mismatch on Recurrent Ischemic Mitral Regurgitation After Ring Annuloplasty.

Background: In ischemic mitral regurgitation (IMR), ring annuloplasty is associated with a significant rate of recurrent MR. Ring size is based on intertrigonal distance without consideration of left ventricular (LV) size. However, LV size is an important determinant of mitral valve (MV) leaflet tethering before and after repair. We aimed to determine whether LV-MV ring mismatch (mismatch of LV size relative to ring size) is associated with recurrent MR in patients with IMR after restrictive ring annuloplasty. Methods: Patients with moderate or severe IMR from the 2 Cardiothoracic Surgical Trials Network IMR trials who received MV repair were examined at 1 year after surgery. Baseline LV size was assessed by LV end-diastolic dimension and LV end-systolic dimension (LVESd). LV-MV ring mismatch was calculated as the ratio of LV to ring size (LV end-diastolic dimension/ring size and LVESd/ring size). Results: At 1 year after ring annuloplasty, 45 of 214 patients with MV repair (21%) had moderate or greater MR. In univariable logistic regression analysis, larger LVESd (P=0.02) and LVESd/ring size (P=0.007) were associated with recurrent MR. In multivariable models adjusted for age, sex, baseline LV ejection fraction, and severe IMR, only LVESd/ring size (odd ratio per 0.5 increase, 2.20; 95% confidence interval, 1.05–4.62; P=0.038) remained significantly associated with 1-year MR recurrence. Conclusions: LV-MV ring size mismatch is associated with increased risk of MR recurrence. This finding may be helpful in guiding choice of ring size to prevent recurrent MR in patients undergoing MV repair and in identifying patients who may benefit from MV repair with additional subvalvular intervention or MV replacement rather than repair alone. Clinical Trial Registration: URL:http://clinicaltrials.gov. Unique identifiers: NCT00806988 and NCT00807040.

Open distal anastomosis in aortic root replacement using axillary cannulation and moderate hypothermia

OBJECTIVE Recent advance in surgical technique facilitates more aggressive approaches for thoracic aortic diseases. We sought to address the outcomes of our strategy of open distal anastomosis with aortic root replacement using axillary cannulation and moderate hypothermia. METHODS A retrospective review of 228 patients who underwent aortic root replacement between July 2004 and December 2007 was performed. RESULTS Axillary artery cannulation was successful in 98% of the attempted cases and resulted in no adverse events in 97%. The axillary artery was the site of arterial cannulation in 89% of the cases, among which 136 patients (60% of the cases) underwent an open distal anastomosis, consisting of the cohort of interest. Median age of the patients was 60 years (ranging from 16 to 89 years) with 79% being male. The principal diagnosis for the operation included aneurysmal disease without aortic dissection (78%), type A aortic dissection with or without aneurysm (12%), and endocarditis (5.9%). Performed operations were modified Bentall operation (53% of the cohort), valve-sparing aortic root replacement (26%), and replacement with a homograft (20%). Hemiarch replacement was added in 43%. Mean +/- standard deviation of the lowest temperature was 27 degrees C +/-2.6 degrees C. There were 5 deaths (mortality 3.7%). A total of 16 patients (12%) had major complications. CONCLUSIONS Open distal anastomosis at the time of aortic root replacement can safely be performed with axillary artery cannulation and moderate hypothermia. Axillary cannulation provides a reliable route of antegrade cerebral perfusion and enables the complex procedure to be performed without deep hypothermic circulatory arrest.