Morley A. Herbert

Reliability of risk algorithms in predicting early and late operative outcomes in high-risk patients undergoing aortic valve replacement

OBJECTIVE Risk algorithms were used to identify a high-risk population for transcatheter aortic valve implantation instead of standard aortic valve replacement in patients with aortic stenosis. We evaluated the efficacy of these methods for predicting outcomes in high-risk patients undergoing aortic valve replacement. METHODS Data were collected on 638 patients identified as having isolated aortic valve replacement between January 1, 1998 and December 31, 2006, using The Society of Thoracic Surgeons (STS) database. Long-term survival was determined from the Social Security Death Index or family contact. Operative risk was calculated using the STS Predicted Risk of Mortality, the EuroSCORE logistic and additive algorithms, and the Ambler Risk Score. Patients at or above the 90th percentile of risk (8.38% for STS, 33.47% for logistic, 12% for additive, 14.3% for Ambler) were identified as high risk. We then compared actual with predicted mortality and each algorithms ability to identify patients with the worst long-term survival. RESULTS Operative mortality was 24 of 638 (3.76%). An additional 121 (19.0%) patients died during the follow-up study period (mean 4.2 +/- 2.7 years). Overall mortality was 145 of 638 (22.7%). Expected versus observed mortality for the high-risk group by algorithm was 13.3% versus 18.8% for STS, 50.9% versus 15.6% for logistic, 14.0% versus 11.9% for additive, and 19.0% versus 13.4% by Ambler. Long-term mortality, per high-risk group, was 64.1% in the STS Predicted Risk of Mortality, 45.3% in the logistic, 45.2% in the additive, and 40.2% in Ambler Risk Score. Logistic regression showed that the STS algorithm was the most sensitive in defining the patients most at risk for long-term mortality. CONCLUSION The STS Predicted Risk of Mortality most accurately predicted perioperative and long-term mortality for the highest risk patients having aortic valve replacement.

Effect of Concomitant Coronary Artery Disease on Procedural and Late Outcomes of Transcatheter Aortic Valve Implantation

BACKGROUND Previous coronary artery bypass grafting increases predicted operative risk for conventional valve replacement, according to the Society of Thoracic Surgeons risk algorithm. Additionally, the presence of coronary artery disease (CAD) has been demonstrated to increase procedural risk with conventional aortic valve replacement. Significant coexisting CAD requires preemptive percutaneous coronary intervention (PCI) in patients under consideration for transcatheter aortic valve implantation (TAVI). This study examined the impact of previous coronary artery bypass grafting or PCI on procedural outcomes and overall survival in patients having TAVI. METHODS Two hundred and one high-risk patients were enrolled in two international feasibility studies from December 2005 to February 2008 for the treatment of aortic stenosis using TAVI. Thirty patients were excluded from analysis due to failure to successfully deploy the valve in the aortic annulus. Data were collected concurrently using an ad hoc database that included operative and long-term survival. Previous cardiovascular intervention prior to TAVI was used to identify the existence of concomitant CAD. Logistic regression along with Kaplan-Meier estimates were employed to establish the association between CAD and survival from TAVI. RESULTS Overall mortality after TAVI was significantly higher among the CAD group (35.7%) in contrast with the non-CAD patients (18.4%), p = 0.01. Logistic regression analysis found that patients who had CAD were 10.1 times more likely to die (95% confidence interval 2.1 to 174.8) within 30 days of the procedure than those who did not. Proportional hazards analysis established that the risk of dying at any point in time was 2.3 times higher among the patients with CAD (95% confidence interval 1.29 to 4.17). Kaplan-Meier survival curves demonstrate improved long-term survival among patients without CAD. CONCLUSIONS Coexisting coronary artery disease negatively impacts procedural outcomes and long-term survival in patients undergoing TAVI, and implies that risk assessment and anticipated outcomes might be inaccurate due to stratification as isolated aortic valve replacement rather than AVR+CABG. Comparison of procedural outcomes, based on operative approach without controlling for unequal distribution of CAD in the cohorts, are likely invalid.

Minimally Invasive Pulmonary Vein Isolation and Partial Autonomic Denervation for Surgical Treatment of Atrial Fibrillation

BACKGROUND We seek to demonstrate the rationale and efficacy of a minimally invasive surgical approach to the treatment of atrial fibrillation (AF) that combines pulmonary vein antral isolation with targeted partial autonomic denervation. METHODS The literature supporting the rationale of this approach is reviewed. Seventy-four patients underwent video-assisted bilateral pulmonary vein antral isolation with confirmation of block and partial autonomic denervation with follow-up of 6 months or greater and have a long-term rhythm monitor at 6 months. RESULTS Success was defined as no episodes greater than 15 seconds of AF on long-term monitoring. Treatment was successful in 83.7% of patients with paroxysmal AF and 56.5% of patients with persistent/long-standing persistent AF. CONCLUSIONS There are evidence-based data that support both pulmonary vein electrical isolation and targeted partial autonomic denervation in the treatment of AF. These techniques can be combined in a minimally invasive surgical approach. Early data suggest this is a safe and efficacious approach for the treatment of paroxysmal AF. Techniques are being developed for the minimally invasive surgical treatment of persistent AF from an epicardial approach.

Conversion in Off-Pump coronary artery bypass grafting: an analysis of predictors and outcomes

BACKGROUND The incidence, predictive factors, and outcomes related to conversion from off-pump coronary artery bypass (OPCAB) to on-pump coronary artery bypass grafting (ONCAB) have not been well defined. We sought to determine the incidence of conversion, predictive factors, and any associated adverse consequences. METHODS From January 2000 through June 2002, 1,644 patients underwent nonemergent OPCAB with 61 patients requiring conversion from OPCAB to ONCAB. These groups were retrospectively compared by univariate and multivariate regression analysis. The converted group was then computer matched 1:3, to a cohort of ONCAB patients to determine differences in outcomes. RESULTS The overall conversion rate was 3.71%. Converted patients compared with a computer-matched ONCAB patients had a higher incidence of operative mortality (18.0% versus 2.7%, p < 0.001). Urgently converted patients had a higher incidence of postoperative cardiac arrest (25% versus 1.1%, p < 0.001), multisystem organ failure (10.7% versus 0.6%, p < 0.001), vascular complications (7.1% versus 1.1%, p = 0.03), and perioperative myocardial infarction (10.7% versus 1.1%, p = 0.02). Predictive factors for conversion were surgeon early in OPCAB experience (odds ratio [OR] 4.4), previous CABG (OR 2.8), and congestive heart failure (OR 2.0). The need for urgent-emergent conversion was highly predictive for operative mortality (OR 7.3) compared with elective conversion. CONCLUSIONS Patients undergoing urgent-emergent but not elective conversion from OPCAB to ONCAB had a significantly higher risk of mortality and morbidity compared with patients whose procedure was initially ONCAB. Variables predictive of conversion included previous CABG, congestive heart failure, and surgeons early in OPCAB experience.

Suture anchor strength revisited

The rapid proliferation of suture anchors continues. Our prior report on the pullout strength of 14 different anchors is supplemented by a similar test conducted on 8 additional anchors. Comparative data on modes of failure and failure strengths (ultimate loads to failure) for these new devices are compared statistically with the previously tested anchors. In a fresh never-frozen porcine femur model, 10 samples of each of the additional anchors tested were threaded with stainless steel sutures and inserted into three different test areas (diaphyseal cortex, metaphyseal cortex, and a cancellous trough). Tensile stress parallel to the axis of insertion was applied at a rate of 12.5 mm/s by an Instron 1321 testing machine (Instron Corp, Canton, MA) until failure and mean anchor failure strengths calculated. The anchors tested were the Mitek G2 as a control, miniMitek, Mitek Superanchor, Mitek Rotator Cuff anchor (Mitek Products, Westwood, MA), Innovasive Devices Radial Osteal Compression device (Innovasive Devices, Hopkinton, MA), Arthrex Fastak (Arthrex Inc, Naples, FL), Arthrotek miniHarpoon (Arthrotek, Warsaw, IN), Orthopedic Biosystems PeBA 3 and PeBA 5 (Orthopedic Biosystems, Scottsdale, AZ), and AME 5.5 screw (American Medical Electronics, Richardson, TX). Failure mode (anchor pullout, suture eyelet cut out, or wire breakage) was generally consistent for each anchor type. The size of insertion hole is clinically important and each anchors performance was evaluated as a function of its minor diameter or drill hole. For screw anchors, the larger the minor diameter of the screw, the higher the mean failure strengths in all three test areas (P = .001). However, larger drill holes for non-screw anchors resulted in lower mean failure strengths in cancellous bone (P = .03) and diaphyseal cortex (P < .005).

Coronary Artery Bypass Graft Failure After On-Pump and Off-Pump Coronary Artery Bypass: Findings From PREVENT IV

BACKGROUND This analysis compares 1-year vein graft patency and major adverse cardiac and cerebral events (MACCE [death, myocardial infarction, or stroke]) in on-pump and off-pump patients enrolled in PREVENT IV (the PRoject of Ex-vivo Vein graft ENgineering via Transfection IV). METHODS The PREVENT IV was a multicenter (107 sites) randomized trial of edifoligide to prevent vein graft failure from neointimal hyperplasia in 3,014 patients undergoing primary, isolated coronary artery bypass grafting (CABG) with at least two vein grafts. One-year angiographic follow-up was completed on 1,920 patients (4,736 grafts) with MACCE follow-up on 99.4% of enrolled patients. RESULTS In all, 2,377 procedures (78.9%) were on pump and 637 (21.1%) were off pump. On-pump patients had more chronic lung disease (17% versus 11%; p < 0.001), congestive heart failure (10% versus 7%; p = 0.03), lower mean ejection fraction (50% versus 55%; p < 0.001), and worse target artery quality (good 63.8% versus 68.1%; fair 26.4% versus 22.7%; poor 9.8% versus 9.2%; p < 0.001). Vein graft failure (more than 75% graft stenosis) in on- versus off-pump patients was 25.3% versus 25.7% (p = 0.62). After adjusting for differences in significant predictors of vein graft failure (target artery quality, surgery time, endoscopic vein harvest, more than 1 distal anastomosis/graft, and patient weight), the odds of vein graft failure was 0.82 (95% confidence interval: 0.67 to 1.00; p = 0.05) for on-pump versus off-pump patients. One-year mortality for on- versus off-pump patients was 3.3% versus 2.5% (p = 0.30); and MACCE was 15.4% versus 11.3% (p = 0.01). The adjusted hazard ratio for 1-year MACCE was 1.31 (95% confidence interval: 1.01-1.69; p = 0.01) for on pump versus off pump. CONCLUSIONS Observed saphenous vein failure rate was 25% in both groups. One-year clinical outcomes (MACCE) were better with off-pump than with on-pump CABG, suggesting benefits not related to vein graft patency.

Ultimate Tensile Failure Loads of a Human Dermal Allograft Rotator Cuff Augmentation

PURPOSE The purpose of this study was to examine the failure mode of supraspinatus tendon repairs with and without human dermal allograft augmentation. METHODS Ten matched pairs of human cadaveric supraspinatus muscles and tendons were detached from their greater tuberosity insertions and then reattached with four simple sutures in 2 suture anchors as a control group. One shoulder from each matched pair was augmented with human dermal allograft secured to the humerus and the supraspinatus tendon using the same sutures and suture anchors. Additional interrupted mattress sutures secured the edges of the dermal allograft to the supraspinatus tendon. Each construct was preloaded at 10 N and then cyclically loaded between 10 N and 100 N for 10 cycles at 20 N/s followed by destructive testing at 33 mm/s. Force and displacement were recorded. RESULTS The mean failure strengths for the control and augmented constructs were 273 +/- 116 N and 325 +/- 74 N, respectively (P = .047). No significant displacement occurred during the cyclic phase, and no anchors failed. These constructs failed by 2 different mechanisms: tendon-suture interface failure (8/10 non-augmented repairs and 6/10 augmented repairs) and suture breakage (2/10 non-augmented repairs and 4/10 augmented repairs). CONCLUSIONS This examination of the failure characteristics and ultimate failure load of supraspinatus tendon tears augmented with GraftJacket (Wright Medical Technology, Arlington, TN) supported the study hypothesis that a human dermal allograft significantly increases the strength of a repaired tendon. CLINICAL RELEVANCE The human dermal allograft can be expected to significantly increase the initial strength of a rotator cuff repair.

Pulmonary vein isolation and autonomic denervation for the management of paroxysmal atrial fibrillation by a minimally invasive surgical approach.

BACKGROUND Advances in technology such as epicardial bipolar radiofrequency pulmonary vein isolation, ganglionated plexi identification, and isolation and thoracoscopic left atrial appendage exclusion have enabled less invasive surgical options for management of atrial fibrillation. METHODS We performed a prospective, nonrandomized study of consecutive patients with symptomatic paroxysmal atrial fibrillation undergoing a video-assisted, minimally invasive surgical ablation procedure. The procedure consisted of bilateral, epicardial pulmonary vein isolation with bipolar radiofrequency, partial autonomic denervation, and selective excision of the left atrial appendage. Minimum follow-up was 1 year with long-term monitoring (24-hour continuous, 14-day event or pacemaker interrogation). RESULTS Between March 2005 and January 2008, 52 patients (35 male), mean age 60.3 years (range, 42-79 years) underwent the procedure. The left atrial appendage was isolated in 88.0% (44/50). Average hospital stay was 5.2 days (range 3-10 days). There were no operative deaths or major adverse cardiac events. On long-term monitoring, freedom from atrial fibrillation/flutter/tachycardia was 86.3% (44/51) and 80.8% (42/52) at 6 and 12 months, respectively. Antiarrhythmic drugs were stopped in 33 of 37 patients and warfarin in 30 of 37 of the patients in whom ablation was successful at 12 months. Freedom from symptoms attributed to atrial fibrillation/flutter/tachycardia was 78.0% (39/50) at 6 months and 63.8% (30/47) at 12 months. CONCLUSIONS Minimally invasive surgical ablation is effective in the management of paroxysmal atrial fibrillation as evidenced by freedom from atrial arrythmias by long-term monitoring at 12 months. Measuring success using clinical symptoms underestimated clinical success as compared with long-term monitoring.

Suture anchors--update 1999.

New suture anchors continue to become available. Our prior reports on the pullout strength of over 50 different anchors is supplemented by a similar test conducted on 25 additional new anchors. This anchor comparison, using an established protocol in fresh porcine femurs, recorded failure strength, failure mode (anchor pullout, suture eyelet cutout, or wire breakage), eyelet size, minor and major diameters, and drill hole sizes. These new anchors were tested in diaphyseal cortex, metaphyseal cortex, and a cancellous trough. Tensile stress parallel to the axis of insertion was applied at a rate of 12.5 mm/sec by an Instron 1321 until failure and mean anchor failure strengths were calculated. Anchors tested included DePuy 4.5 prototypes D1, D2 Catera 4.5, and D3; DePuy 3.5 prototypes D4- Catera 3.5, D5, and D6; Mainstay 2.7, 3.5, 4.5; ROC EZ 2.8, EZ 3.5, and XS 3.5; Ultrafix RC and Ultrafix MiniMite; 1.3 MicroMitek, Panalok 3.5, and Tacit 2.0; Umbrella Harpoon; PeBA 2.8, 4.0, 6.5; and Stryker 1.9, 2.7, 3.4, and 4.5 prototypes. Screw anchors still tend to have higher values, but for the newer nonscrew designs this distinction is less apparent. The new biodegradable anchors were all composed of poly L-lactic acid suggesting a trend away from other polymers, and these new biodegradable anchors showed load-to-failure strengths comparable to others in their class. All anchors were stronger than the suture for which they are designed to accommodate.

High-risk patients referred for transcatheter aortic valve implantation: management and outcomes.

BACKGROUND Aortic valve replacement (AVR) is the treatment of choice for critical aortic stenosis. Selected patients have not previously been referred for AVR because of excessive risk of mortality and morbidity with surgery. The option of transcatheter aortic valve implantation (TAVI) has increased referral of this high-risk cohort for therapeutic intervention. We report the management and outcomes of these patients. METHODS Patients referred for TAVI from December 2005 to December 2007 were evaluated and followed up for intermediate-term all cause mortality. Patients received medical management, TAVI, conventional AVR, or balloon valvuloplasty (BAV) based on risk profile, hemodynamic and echocardiographic criteria, physician judgment, or patient choice. Patients were compared for demographics, Society of Thoracic Surgeons predicted risk of mortality score, and outcomes after AVR, TAVI, or BAV. RESULTS One hundred five patients were referred for TAVI during a 24-month period. Fifty-two patients (49.5%) received medical management, 16 (15.2%) conventional AVR, 21 (20.0%) received TAVI, and 16 (15.2%) received BAV. Patients were classified as medical management because of physician or patient choice, not meeting TAVI criteria, or underevaluation for a possible procedure. For all patients the average length of follow-up was 159 +/- 147 days. Patients receiving BAV had a Society of Thoracic Surgeons predicted risk of mortality score greater than those having medical management, AVR, or TAVI. Thirty-day mortality was 1 of 16 patients (6.3%) for AVR, 2 of 21 patients (9.5%) with TAVI, 2 of 16 patients (12.5%) for BAV, and 7 of 52 patients (13.5%) for the medical management cohort. Overall mortality during follow-up was 42.3% (22 of 52 patients) for medical management, 19.1% (4 of 21 patients) for TAVI, 12.5% (2 of 16 patients) for AVR, and 37.5% (6 of 16 patients) for BAV. CONCLUSIONS The population of patients screened for transcatheter therapy is complex and heterogeneous. Medical management alone demonstrates a high mortality rate, and BAV, although providing transient symptomatic relief, does not favorably impact survival. The majority of referred patients (65.7%), including those that declined intervention, were candidates for some form of valve replacement therapy, either TAVI or AVR. Transcatheter aortic valve implantation can be performed in appropriately selected patients with good early and immediate-term outcomes.