Stuart Lander - Academia.edu (original) (raw)

Papers by Stuart Lander

Research paper thumbnail of First and recurrent events after percutaneous coronary intervention: implications for survival analyses

Scandinavian Cardiovascular Journal, 2019

Objectives. Using composite endpoints and/or only first events in clinical research result in inf... more Objectives. Using composite endpoints and/or only first events in clinical research result in information loss and alternative statistical methods which incorporate recurrent event data exist. We compared information-loss under traditional analyses to alternative models. Design. We conducted a retrospective analysis of patients who underwent percutaneous coronary intervention (Jan2010-Dec2014) and constructed Cox models for a composite endpoint (readmission/death), a shared frailty model for recurrent events, and a joint frailty (JF) model to simultaneously account for recurrent and terminal events and evaluated the impact of heart failure (HF) on the outcome. Results. Among 4901 patients, 2047(41.8%) experienced a readmission or death within 1 year. Of those with recurrent events, 60% had 1 readmission and 6% had >4; a total of 121(2.5%) patients died during follow-up. The presence of HF conferred an adjusted Hazard ratio (HR) of 1.32 (95% CI: 1.18-1.47, p < .001) for the risk of composite endpoint (Cox model), 1.44 (95% CI: 1.36-1.52, p < .001) in the frailty model, and 1.34 (95% CI:1.22-1.46, p < .001) in the JF model. However, HF was not associated with death (HR 0.87, 95% CI: 0.52-1.48, p ¼ .61) in the JF model. Conclusions. Using a composite endpoint and/or only the first event yields substantial loss of information, as many individuals endure >1 event. JF models reduce bias by simultaneously providing event-specific HRs for recurrent and terminal events.

Research paper thumbnail of Libman-Sacks Endocarditis Involving a Bioprosthesis in the Aortic Valve Position in Systemic Lupus Erythematosus

The American Journal of Cardiology, 2019

Described herein is a 39-year-old man with systemic lupus erythematosus not receiving corticoster... more Described herein is a 39-year-old man with systemic lupus erythematosus not receiving corticosteroid therapy who developed Libman-Sacks endocarditis causing stenosis of a bioprosthesis in the aortic valve position.

Research paper thumbnail of Effect of Progressive Left Ventricular Dilatation on Degree of Mitral Regurgitation Secondary to Mitral Valve Prolapse

The American Journal of Cardiology, 2019

Described herein is a 71-year-old man who at age 61 was found by echocardiogram to have severe mi... more Described herein is a 71-year-old man who at age 61 was found by echocardiogram to have severe mitral regurgitation (MR) from mitral valve prolapse. During the subsequent 9 years the MR progressively lessened as his left ventricular cavity dilated and his ejection fraction progressively fell such that just before orthotopic heart transplantation the degree of MR was no longer severe, and the prolapse of the mitral leaflets had disappeared. This report describes this unique patient.

Research paper thumbnail of Event dependence in the analysis of cardiovascular readmissions postpercutaneous coronary intervention

Journal of Investigative Medicine, 2019

Recurrent hospitalizations are common in longitudinal studies; however, many forms of cumulative ... more Recurrent hospitalizations are common in longitudinal studies; however, many forms of cumulative event analyses assume recurrent events are independent. We explore the presence of event dependence when readmissions are spaced apart by at least 30 and 60 days. We set up a comparative framework with the assumption that patients with emergency percutaneous coronary intervention (PCI) will be at higher risk for recurrent cardiovascular readmissions than those with elective procedures. A retrospective study of patients who underwent PCI (January 2008–December 2012) with their follow-up information obtained from a regional database for hospitalization was conducted. Conditional gap time (CG), frailty gamma (FG) and conditional frailty models (CFM) were constructed to evaluate the dependence of events. Relative bias (%RB) in point estimates using CFM as the reference was calculated for comparison of the models. Among 4380 patients, emergent cases were at higher risk as compared with electi...

Research paper thumbnail of Major Adverse Renal and Cardiac Events Following Coronary Angiography and Cardiac Surgery

The Annals of thoracic surgery, Jan 2, 2018

Patients at high risk for developing post-procedural complications may receive iodixanol, an iso-... more Patients at high risk for developing post-procedural complications may receive iodixanol, an iso-osmolar contrast, during coronary angiography to minimize the risk of renal toxicity. For those who additionally require cardiac surgery, the wait-time between angiography and surgery may be a modifiable factor capable of mitigating poor surgical outcomes; however, there have been inconsistsent reports regarding the optimal wait-time. We sought to determine the effects of wait time between angiogram and cardiac surgery, as well as contrast induced acute injury (CI-AKI) on the development of major adverse renal and cardiac events (MARCE). We merged datasets to identify adults who underwent coronary angiography with iodixanol and subsequent cardiac surgery. Of 965 patients, 126 (13.1%) developed CI-AKI; 133 (13.8%) experienced MARCE within 30 days and 253 (26.2%) within 1 year of surgery. After adjusting for CI-AKI, age, and Thakar acute renal failure score, the effect of wait-time lost si...

Research paper thumbnail of Heat-denaturation kinetics of lignin peroxidases from Phanerochaete chrysosporium

Enzyme and Microbial Technology, 1990

Abstract Many practical applications have been proposed for the lignin peroxidases from Phaneroch... more Abstract Many practical applications have been proposed for the lignin peroxidases from Phanerochaete chrysosporium. To design and develop these technologies, more information regarding the stability of these enzymes is required. Heat-denaturation studies were conducted on crude and partially purified lignin peroxidases obtained from P. chrysosporium under nitrogen-limiting and nitrogen-sufficient conditions. At temperatures of 37°C, or below, no significant loss of activity was observed over a 5-d period. At temperatures between 50 and 60°C, lignin peroxidase activity rapidly decreased. The heat-denaturation kinetics under these conditions was not first order. A four-parameter model that describes the heat-denaturation kinetics of crude and partially purified lignin peroxidases was developed. Based on the successful application of this model, it is suggested that P. chrysosporium produces lignin peroxidases that can be separated into at least two groups with similar decay constants within a group and different decay constants between groups.

Research paper thumbnail of Percutaneous closure of multiple atrial septal defects with three Amplatzer septal occluder devices

Catheterization and Cardiovascular Interventions, 2004

We report on the successful closure of three atrial septal defects with three Amplatzer septal oc... more We report on the successful closure of three atrial septal defects with three Amplatzer septal occluders in a 55-year-old woman.

Research paper thumbnail of Aneurysm of the False Channel of Descending Thoracic Aorta Years After Operative Excision of the Initiating Aortic Dissection Tear in Ascending Aorta

The American Journal of Geriatric Cardiology, 2000

Research paper thumbnail of Validation of the i-STAT handheld activated clotting time for use with bivalirudin

The American Journal of Cardiology, 2004

Bivalirudin is being used more frequently as an anticoagulant in the cardiac catheterization labo... more Bivalirudin is being used more frequently as an anticoagulant in the cardiac catheterization laboratory. Newer devices, used to measure activated clotting time (ACT), have not been thoroughly tested for use with bivalirudin. One such device, the i-STAT ACT, measures the generation of activated thrombin to determine the level of anticoagulation. Our study demonstrated a high level of agreement between the i-STAT ACT and the Hemochron ACT in patients anticoagulated with bivalirudin. In addition, the i-STAT was shown to have an extremely high degree of reproducibility. ᮊ2004 by Excerpta Medica, Inc.

Research paper thumbnail of Observations on the Heart - Congenitally Bicuspid Stenotic Aortic Valves in Octogenarians

The American journal of geriatric cardiology, 1999

Research paper thumbnail of First and recurrent events after percutaneous coronary intervention: implications for survival analyses

Scandinavian Cardiovascular Journal, 2019

Objectives. Using composite endpoints and/or only first events in clinical research result in inf... more Objectives. Using composite endpoints and/or only first events in clinical research result in information loss and alternative statistical methods which incorporate recurrent event data exist. We compared information-loss under traditional analyses to alternative models. Design. We conducted a retrospective analysis of patients who underwent percutaneous coronary intervention (Jan2010-Dec2014) and constructed Cox models for a composite endpoint (readmission/death), a shared frailty model for recurrent events, and a joint frailty (JF) model to simultaneously account for recurrent and terminal events and evaluated the impact of heart failure (HF) on the outcome. Results. Among 4901 patients, 2047(41.8%) experienced a readmission or death within 1 year. Of those with recurrent events, 60% had 1 readmission and 6% had >4; a total of 121(2.5%) patients died during follow-up. The presence of HF conferred an adjusted Hazard ratio (HR) of 1.32 (95% CI: 1.18-1.47, p < .001) for the risk of composite endpoint (Cox model), 1.44 (95% CI: 1.36-1.52, p < .001) in the frailty model, and 1.34 (95% CI:1.22-1.46, p < .001) in the JF model. However, HF was not associated with death (HR 0.87, 95% CI: 0.52-1.48, p ¼ .61) in the JF model. Conclusions. Using a composite endpoint and/or only the first event yields substantial loss of information, as many individuals endure >1 event. JF models reduce bias by simultaneously providing event-specific HRs for recurrent and terminal events.

Research paper thumbnail of Libman-Sacks Endocarditis Involving a Bioprosthesis in the Aortic Valve Position in Systemic Lupus Erythematosus

The American Journal of Cardiology, 2019

Described herein is a 39-year-old man with systemic lupus erythematosus not receiving corticoster... more Described herein is a 39-year-old man with systemic lupus erythematosus not receiving corticosteroid therapy who developed Libman-Sacks endocarditis causing stenosis of a bioprosthesis in the aortic valve position.

Research paper thumbnail of Effect of Progressive Left Ventricular Dilatation on Degree of Mitral Regurgitation Secondary to Mitral Valve Prolapse

The American Journal of Cardiology, 2019

Described herein is a 71-year-old man who at age 61 was found by echocardiogram to have severe mi... more Described herein is a 71-year-old man who at age 61 was found by echocardiogram to have severe mitral regurgitation (MR) from mitral valve prolapse. During the subsequent 9 years the MR progressively lessened as his left ventricular cavity dilated and his ejection fraction progressively fell such that just before orthotopic heart transplantation the degree of MR was no longer severe, and the prolapse of the mitral leaflets had disappeared. This report describes this unique patient.

Research paper thumbnail of Event dependence in the analysis of cardiovascular readmissions postpercutaneous coronary intervention

Journal of Investigative Medicine, 2019

Recurrent hospitalizations are common in longitudinal studies; however, many forms of cumulative ... more Recurrent hospitalizations are common in longitudinal studies; however, many forms of cumulative event analyses assume recurrent events are independent. We explore the presence of event dependence when readmissions are spaced apart by at least 30 and 60 days. We set up a comparative framework with the assumption that patients with emergency percutaneous coronary intervention (PCI) will be at higher risk for recurrent cardiovascular readmissions than those with elective procedures. A retrospective study of patients who underwent PCI (January 2008–December 2012) with their follow-up information obtained from a regional database for hospitalization was conducted. Conditional gap time (CG), frailty gamma (FG) and conditional frailty models (CFM) were constructed to evaluate the dependence of events. Relative bias (%RB) in point estimates using CFM as the reference was calculated for comparison of the models. Among 4380 patients, emergent cases were at higher risk as compared with electi...

Research paper thumbnail of Major Adverse Renal and Cardiac Events Following Coronary Angiography and Cardiac Surgery

The Annals of thoracic surgery, Jan 2, 2018

Patients at high risk for developing post-procedural complications may receive iodixanol, an iso-... more Patients at high risk for developing post-procedural complications may receive iodixanol, an iso-osmolar contrast, during coronary angiography to minimize the risk of renal toxicity. For those who additionally require cardiac surgery, the wait-time between angiography and surgery may be a modifiable factor capable of mitigating poor surgical outcomes; however, there have been inconsistsent reports regarding the optimal wait-time. We sought to determine the effects of wait time between angiogram and cardiac surgery, as well as contrast induced acute injury (CI-AKI) on the development of major adverse renal and cardiac events (MARCE). We merged datasets to identify adults who underwent coronary angiography with iodixanol and subsequent cardiac surgery. Of 965 patients, 126 (13.1%) developed CI-AKI; 133 (13.8%) experienced MARCE within 30 days and 253 (26.2%) within 1 year of surgery. After adjusting for CI-AKI, age, and Thakar acute renal failure score, the effect of wait-time lost si...

Research paper thumbnail of Heat-denaturation kinetics of lignin peroxidases from Phanerochaete chrysosporium

Enzyme and Microbial Technology, 1990

Abstract Many practical applications have been proposed for the lignin peroxidases from Phaneroch... more Abstract Many practical applications have been proposed for the lignin peroxidases from Phanerochaete chrysosporium. To design and develop these technologies, more information regarding the stability of these enzymes is required. Heat-denaturation studies were conducted on crude and partially purified lignin peroxidases obtained from P. chrysosporium under nitrogen-limiting and nitrogen-sufficient conditions. At temperatures of 37°C, or below, no significant loss of activity was observed over a 5-d period. At temperatures between 50 and 60°C, lignin peroxidase activity rapidly decreased. The heat-denaturation kinetics under these conditions was not first order. A four-parameter model that describes the heat-denaturation kinetics of crude and partially purified lignin peroxidases was developed. Based on the successful application of this model, it is suggested that P. chrysosporium produces lignin peroxidases that can be separated into at least two groups with similar decay constants within a group and different decay constants between groups.

Research paper thumbnail of Percutaneous closure of multiple atrial septal defects with three Amplatzer septal occluder devices

Catheterization and Cardiovascular Interventions, 2004

We report on the successful closure of three atrial septal defects with three Amplatzer septal oc... more We report on the successful closure of three atrial septal defects with three Amplatzer septal occluders in a 55-year-old woman.

Research paper thumbnail of Aneurysm of the False Channel of Descending Thoracic Aorta Years After Operative Excision of the Initiating Aortic Dissection Tear in Ascending Aorta

The American Journal of Geriatric Cardiology, 2000

Research paper thumbnail of Validation of the i-STAT handheld activated clotting time for use with bivalirudin

The American Journal of Cardiology, 2004

Bivalirudin is being used more frequently as an anticoagulant in the cardiac catheterization labo... more Bivalirudin is being used more frequently as an anticoagulant in the cardiac catheterization laboratory. Newer devices, used to measure activated clotting time (ACT), have not been thoroughly tested for use with bivalirudin. One such device, the i-STAT ACT, measures the generation of activated thrombin to determine the level of anticoagulation. Our study demonstrated a high level of agreement between the i-STAT ACT and the Hemochron ACT in patients anticoagulated with bivalirudin. In addition, the i-STAT was shown to have an extremely high degree of reproducibility. ᮊ2004 by Excerpta Medica, Inc.

Research paper thumbnail of Observations on the Heart - Congenitally Bicuspid Stenotic Aortic Valves in Octogenarians

The American journal of geriatric cardiology, 1999