Faculty Bibliography

BACKGROUND: Recent data suggest that octogenarians' long-term survival after complete coronary artery bypass graft revascularization is superior to incomplete revascularization. Discriminating between variable definitions of "complete" complicates interpretation of survival data. We aimed to clarify octogenarian long-term survival rates by stratifying revascularization subtypes. METHODS AND RESULTS: From 1986 to 2007, 580 patients 80 to 94 years of age underwent coronary artery bypass graft. Functional complete revascularization was defined as at least 1 graft to all diseased coronary vessels with >50% stenosis. Traditional complete revascularization was defined as 1 graft to each major arterial system with at least 50% stenosis. Incomplete revascularization was defined as leaving diseased, ungrafted regions. Revascularization was functional in 279 (48%), traditional in 181 (31%), and incomplete in 120 (21%). Long-term survival was evaluated by Kaplan-Meier analysis. Of 537 operative survivors, there were 402 late deaths. Cumulative long-term survival totaled 2890 patient-years. Late survival (Kaplan-Meier) was similar between functional (mean, 6.8 years) and traditional (6.7 years) groups (P=0.51), but diminished with incomplete (4.2 years) revascularization (P=0.007). Survival by group at 5 years was: 59+/-3% functional, 57+/-4% traditional, and 45+/-5% incomplete. Survival at 8 years was: 40+/-3% functional, 37+/-4% traditional, and 26+/-5% incomplete. To minimize selection bias in patients with limited life expectancy, Kaplan-Meier analysis was repeated including only patients with survival >12 months. Survival was again impaired with incomplete revascularization (P=0.04), and there was no difference between functional and traditional complete revascularization (P=0.73). CONCLUSIONS: Bypassing all diseased arterial vessels after revascularization does not afford significant long-term survival advantage compared to a traditional approach. Incomplete revascularization, related to more extensive disease, is associated with an 18% decline in survival. These data suggest that it is important to avoid incomplete revascularization in octogenarians, but the supplementary endeavor required to perform functional complete revascularization does not improve survival.

BACKGROUND: The HeartMate II (Thoratec, Pleasanton, CA) is an effective bridge to transplantation (BTT) but requires anti-coagulation with warfarin and aspirin. We evaluated the risk of thromboembolism and hemorrhage related to the degree of anti-coagulation as reflected by the international normalized ratio (INR). METHODS: INRs were measured monthly for 6 months in all discharged HeartMate II BTT patients and at an event. Each INR was assigned to ranges of INRs. Adverse events analyzed were ischemic and hemorrhagic stroke, pump thrombosis, and bleeding requiring surgery or transfusion. Events were correlated to the INR during the event and at the start of the month. RESULTS: In 331 patients discharged on support, 10 had thrombotic events (9 ischemic strokes, 3 pump thromboses), and 58 had hemorrhagic events (7 strokes, 4 hemorrhages requiring surgery, and 102 requiring transfusions). The median INR was 2.1 at discharge and 1.90 at 6 months. Although the incidence of stroke was low, 40% of ischemic strokes occurred in patients with INRs < 1.5 and 33% of hemorrhagic strokes were in patients with INRs > 3.0. The highest incidence of bleeding was at INRs > 2.5. CONCLUSIONS: The rate of thromboembolism during long-term outpatient support with the HeartMate II is low. The low number of thrombotic events appears to be offset by a greater number of hemorrhagic events. An appropriate target INR is 1.5 to 2.5 in addition to aspirin therapy. In patients having recurrent episodes of bleeding, the risk of lowering the target INR appears to be small.

Optical coherence tomography (OCT) allows for the visualization of micron-scale structures within nontransparent biological tissues. For the first time, we demonstrate the use of OCT in identifying components of the cardiac conduction system and other structures in the explanted human heart. Reconstructions of cardiac structures up to 2 mm below the tissue surface were achieved and validated with Masson Trichrome histology in atrial, ventricular, sinoatrial nodal, and atrioventricular nodal preparations. The high spatial resolution of OCT provides visualization of cardiac fibers within the myocardium, as well as elements of the cardiac conduction system; however, a limiting factor remains its depth penetration, demonstrated to be approximately 2 mm in cardiac tissues. Despite its currently limited imaging depth, the use of OCT to identify the structural determinants of both normal and abnormal function in the intact human heart is critical in its development as a potential aid to intracardiac arrhythmia diagnosis and therapy.

OBJECTIVES: This study sought to evaluate the use of a continuous-flow rotary left ventricular assist device (LVAD) as a bridge to heart transplantation. BACKGROUND: LVAD therapy is an established treatment modality for patients with advanced heart failure. Pulsatile LVADs have limitations in design precluding their use for extended support. Continuous-flow rotary LVADs represent an innovative design with potential for small size and greater reliability by simplification of the pumping mechanism. METHODS: In a prospective, multicenter study, 281 patients urgently listed (United Network of Organ Sharing status 1A or 1B) for heart transplantation underwent implantation of a continuous-flow LVAD. Survival and transplantation rates were assessed at 18 months. Patients were assessed for adverse events throughout the study and for quality of life, functional status, and organ function for 6 months. RESULTS: Of 281 patients, 222 (79%) underwent transplantation, LVAD removal for cardiac recovery, or had ongoing LVAD support at 18-month follow-up. Actuarial survival on support was 72% (95% confidence interval: 65% to 79%) at 18 months. At 6 months, there were significant improvements in functional status and 6-min walk test (from 0% to 83% of patients in New York Heart Association functional class I or II and from 13% to 89% of patients completing a 6-min walk test) and in quality of life (mean values improved 41% with Minnesota Living With Heart Failure and 75% with Kansas City Cardiomyopathy questionnaires). Major adverse events included bleeding, stroke, right heart failure, and percutaneous lead infection. Pump thrombosis occurred in 4 patients. CONCLUSIONS: A continuous-flow LVAD provides effective hemodynamic support for at least 18 months in patients awaiting transplantation, with improved functional status and quality of life. (Thoratec HeartMate II Left Ventricular Assist System [LVAS] for Bridge to Cardiac Transplantation; NCT00121472).

BACKGROUND: Myocardial systolic strain patterns in dilated cardiomyopathy are considered non-homogeneous but have not been investigated with magnetic resonance imaging (MRI)-based multiparametric systolic strain analysis. Left ventricular (LV) 3-dimensional (3D) multiparametric systolic strain analysis is sensitive to regional contractility and is generated from sequential MRI of tissue-tagging gridline-point displacements. METHODS: Sixty normal human volunteers underwent MRI-based 3D systolic strain analysis to supply normal average and standard deviation values for each of three strain parameters at each of 15,300 individual LV grid-points. Patient-specific multiparametric systolic strain data from each dilated cardiomyopathy patient (n = 10) were then subjected to a point-by-point comparison (n = 15,300 LV points) to the normal strain database for three individual strain components (45,900 database comparisons per patient). The resulting composite multiparametric Z-score values (standard deviation from normal average) were color contour mapped over patient-specific 3D LV geometry to detect the normalized regional contractile patterns associated with dilated cardiomyopathy. RESULTS: Average multiparametric strain Z-score values varied significantly according to ventricular level (p = 0.001) and region (p = 0.003). Apical Z-scores were significantly less than those in both the base (p = 0.037) and mid-ventricle (p = 0.002), whereas anterolateral wall Z-scores were less than those in the anteroseptal (p = 0.023) and posteroseptal walls (p = 0.028). CONCLUSIONS: MRI-based multiparametric systolic strain analysis suggests that myocardial systolic strain in patients with dilated cardiomyopathy has a heterogeneous regional distribution and, on average, falls almost 2 standard deviations from normal.