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Biomedical subjects

Michael H Sketch

Publications and source records attributed to Michael H Sketch.

At least 19 recordsLinked to original sources
PubMed2007

Ventricular ectopy: impact of self-reported stress after myocardial infarction.

BACKGROUND: Although psychologic stress has been implicated in the pathogenesis of ventricular arrhythmias, the relationship between self-reported stress and ventricular ectopy has not been evaluated under naturalistic conditions in acute post-myocardial infarction (MI) patients, a group at elevated risk for arrhythmias. MATERIALS AND METHODS: Diary-reported stress was measured during 24-hour Holter monitoring in 80 patients (52 men and 28 women) approximately 12 weeks after their MI. In addition, state and trait anxiety were measured using the Spielberger State and Trait Anxiety Inventory, which was administered at the beginning of the 24-hour Holter monitoring session. The relationships between diary-reported stress, anxiety, and ventricular ectopy were evaluated. RESULTS: Mean diary-reported stress was associated with total ventricular ectopy (beta = .29, P = .01). State anxiety was also associated with 24-hour ectopy (beta = .24, P = .04); however, trait anxiety was not significantly associated with ectopy. Temporal analyses of the relationship between stress and ectopy showed that diary-reported stress was associated with an increase in the number of ventricular premature beats occurring in the following hour (beta = .74, P < .0001). CONCLUSIONS: These findings extend existing evidence linking psychologic factors to ventricular arrhythmias by demonstrating that psychologic stress predicts increased arrhythmic activity during routine daily activities in post-MI patients.

Adult↗
PubMed2006

Impact of internal mammary artery conduit on long-term outcomes after percutaneous intervention of saphenous vein graft.

BACKGROUND: The influence of an internal mammary artery (IMA) graft on long-term outcomes after percutaneous saphenous vein graft (SVG) intervention is currently unknown. METHODS AND RESULTS: To examine the impact of IMA on outcomes in patients undergoing SVG interventions, we analyzed 2119 patients from the Duke Cardiovascular Disease Database (1986-2003) with prior coronary artery bypass surgery undergoing cardiac catheterization who had at least 1 SVG graft. Patients were categorized into 4 groups: group I, SVG intervention and patent IMA; group II, no SVG intervention and patent IMA; group III, SVG intervention without patent IMA; and group IV, no SVG intervention without patent IMA. At a median follow-up of 4.8 years (interquartile range, 2.1 to 8.8 years), adjusted survival rates in groups I, II, III, and IV were 72.8%, 72.3%, 64.5%, and 58.9%, respectively. Multivariate Cox proportional hazards modeling showed similar survival for groups I and II (P=0.63) and for groups III and IV (P=0.33). The presence of IMA graft was related to lower long-term mortality (adjusted hazard ratio [HR], 0.69; 95% CI, 0.58 to 0.82), whereas SVG intervention was not associated with long-term mortality (adjusted HR, 0.94; 95% CI, 0.81 to 1.10). In contrast, the adjusted event-free rates for nonfatal myocardial infarction were lower in the SVG intervention groups (groups I and III) than in the non-SVG intervention groups (groups II and IV) (HR for SVG intervention versus no SVG intervention, 3.19; 95% CI, 2.18 to 4.66), with the presence of patent IMA conferring no significant benefit on this outcome (HR, 1.37; 95% CI, 0.91 to 2.08). CONCLUSIONS: In patients undergoing SVG interventions, survival, but not nonfatal myocardial infarction, is favorably influenced by the presence of patent IMA. In contrast, SVG intervention had no measurable survival benefit but was associated with an increased risk of nonfatal myocardial infarction.

Aged↗
PubMed2006

Improved detection of coronary artery disease by stress perfusion cardiovascular magnetic resonance with the use of delayed enhancement infarction imaging.

OBJECTIVES: We tested a pre-defined visual interpretation algorithm that combines cardiovascular magnetic resonance (CMR) data from perfusion and infarction imaging for the diagnosis of coronary artery disease (CAD). BACKGROUND: Cardiovascular magnetic resonance can assess both myocardial perfusion and infarction with independent techniques in a single session. METHODS: We prospectively enrolled 100 consecutive patients with suspected CAD scheduled for X-ray coronary angiography. Patients had comprehensive clinical evaluation, including Rose angina questionnaire, 12-lead electrocardiography, C-reactive protein, and calculation of Framingham risk. Cardiovascular magnetic resonance included cine, adenosine-stress and rest perfusion-CMR, and delayed enhancement-CMR (DE-CMR) for infarction imaging. Matched stress-rest perfusion defects in the absence of infarction by DE-CMR were considered artifactual. All patients underwent X-ray angiography within 24 h of CMR. RESULTS: Ninety-two patients had complete CMR examinations. Significant CAD (> or =70% stenosis) was found in 37 patients (40%). The combination of perfusion and DE-CMR had a sensitivity, specificity, and accuracy of 89%, 87%, and 88%, respectively, for CAD diagnosis, compared with 84%, 58%, and 68%, respectively, for perfusion-CMR alone. The combination had higher specificity and accuracy (p < 0.0001), owing to incorporating the exceptionally high specificity (98%) of DE-CMR. Receiver operating characteristic curve analysis demonstrated the combination provided better performance than cine, perfusion, or DE-CMR alone. The accuracy was high in single-vessel and multivessel disease and independent of CAD location. Multivariable analysis including standard clinical parameters demonstrated the combination was the strongest independent CAD predictor. CONCLUSIONS: A combined perfusion and infarction CMR examination with a visual interpretation algorithm can accurately diagnose CAD in the clinical setting. The combination is superior to perfusion-CMR alone.

Aged↗
PubMed2006

Clinical correlates of long-term mortality after percutaneous interventions of saphenous vein grafts.

BACKGROUND: Increasing number of patients undergo percutaneous intervention of saphenous vein grafts (SVGs). However, the clinical factors associated with long-term mortality after SVG interventions are currently less known. Accordingly, the goal of present study was to evaluate clinical correlates of long-term mortality and to develop a simple bedside tool for risk stratification in patients undergoing SVG interventions. METHODS: We analyzed 1019 patients undergoing SVG interventions from the Duke Cardiovascular Disease Database (1986-2003). Cox proportional hazards model was used to identify baseline variables associated with long-term mortality, and the model variables were then used to construct a nomogram for survival probability at 4 years. RESULTS: At a median follow-up of 4 years, 24% of those undergoing SVG interventions died (interquartile range 2-7 years). Independent correlates of death at follow-up on multivariable analysis included presenting heart rate (hazard ratio [HR] 1.02, 95% CI 1.01-1.03), diabetes (HR 1.73, 95% CI 1.37-2.18), presenting heart failure (HR 1.62, 95% CI 1.27-2.06), age (per 10-year increase, HR 1.29, 95% CI 1.13-1.46), peripheral vascular disease (HR 1.59, 95% CI 1.23-2.04), renal insufficiency (HR 2.01, 95% CI 1.36-2.97), patent internal mammary graft (HR 0.67, 95% CI 0.53-0.86), body mass index < or = 25 kg/m2 (HR 0.91, 95% CI 0.85-0.97), carotid bruit (HR 1.44, 95% CI 1.12-1.85), S3 ventricular gallop (HR 1.83, 95% CI 1.11-3.03), and hypertension (HR 1.38, 95% CI 1.04-1.83) (c-index 0.83). Bootstrap validation confirmed excellent internal validity of the model (mean c-index 0.84, 95% CI 0.80-0.85). CONCLUSION: Long-term survival after SVG intervention is poor, with one fourth of patients dying at median follow-up of 4 years. The nomogram developed using the model variables provides a method for clinicians to advise patients undergoing SVG interventions regarding their long-term prognosis, thereby enhancing discharge and long-term follow-up planning and setting up of realistic expectations.

Aged↗
PubMed2006

Selection of surgical or percutaneous coronary intervention provides differential longevity benefit.

BACKGROUND: Treatment of coronary artery disease (CAD) is evolving with better medications, improvements in percutaneous coronary intervention (PCI), and enhanced techniques for coronary artery bypass grafting (CABG). METHODS: In this study, 18,481 patients with significant (>75% stenosis) CAD treated at a single center between 1986 and 2000 were assigned to one of three groups based on initial treatment strategy: medical therapy (MED) (n = 6862), PCI (n = 6292), or CABG (n = 5327). Each group was categorized into 3 groups according to baseline severity of CAD: low-severity (predominantly 1-vessel), intermediate-severity (predominantly 2-vessel), and high-severity (all 3-vessel), and prospectively evaluated in Cox models for all-cause mortality adjusted for cardiac risk, comorbidity, and propensity for selection of a specific treatment. Treatments were compared for the entire period and three eras (1: 1986 to 1990; 2: 1991 to 1995; 3: 1996 to 2000), the last encompassing widespread availability of PCI with stenting. RESULTS: Survival significantly improved in all groups for all degrees of CAD, despite increasing severity of illness. Revascularization strategies provided significant survival over MED with 8.1, 10.6, and 23.6 additional months per 15 years of follow-up for low-severity, intermediate-severity, and high-severity CAD, respectively. Therapeutic improvements led to increased survival of 5.3 additional months per 7 years of follow-up (95% confidence interval, 0.2 to 10.2; p = 0.039) in era 3 for CABG compared with PCI for high-severity CAD. CONCLUSIONS: Initial revascularization strategies result in significant survival advantage over MED for all CAD levels. Patients with high-severity CAD have reduced survival with PCI compared with those initially treated with CABG.

Aged↗
PubMed2006

Acute myocardial infarction: safety of cardiac MR imaging after percutaneous revascularization with stents.

PURPOSE: To retrospectively determine the safety of cardiac magnetic resonance (MR) imaging performed early (<14 days) after coronary stent implantation in patients with acute myocardial infarction (AMI). MATERIALS AND METHODS: This HIPPA-compliant study was approved by the institutional review board; the informed consent requirement was waived. Consecutive patients with AMI who underwent cardiac MR imaging (study group) shortly after stent implantation (median, 3 days) were compared with control subjects who did not undergo MR imaging and were matched for clinical factors and angiographic extent of coronary disease. A 1.5-T MR imager was used to evaluate cine function, perfusion, and viability. Rates of death, nonfatal myocardial infarction, or revascularization 30 days and 6 months after stent implantation were compared with chi(2) analysis. RESULTS: The study group consisted of 66 patients (median age, 56 years; 17 women) with 97 stents, 38 (39%) of which were drug eluting. The control group included 124 patients (median age, 58 years; 23% women) with 197 stents, 21 (10.7%) of which were drug eluting. There was no significant (P = .13) difference in the combined end point of death, nonfatal myocardial infarction, or revascularization between the study (2.0% [95% confidence interval: 0.0%, 4.5%]) and control (6.5% [95% confidence interval: 1.6%, 11.3%]) groups at 30-day follow-up. The event-free survival rate at 6-month follow-up was 91% in the study group and 83.7% in the control group (P = .18). Considering the end points separately, there was no difference in the event rate at 30-day or 6-month follow-up between groups. No adverse cardiovascular events occurred in patients with drug-eluting stents who underwent MR imaging. CONCLUSION: Cardiac MR imaging performed shortly after AMI and percutaneous revascularization with bare metal or drug-eluting stents appears safe. The risk of adverse cardiovascular events is low and similar to that in patients who do not undergo MR imaging.

Aged↗
PubMed2005

A new anatomic score for prognosis after cardiac catheterization in patients with previous bypass surgery.

OBJECTIVES: The purpose of this study was to determine the value of a new anatomic score for prognosis after diagnostic catheterization in patients with previous coronary artery bypass grafting (CABG). BACKGROUND: Previous CABG patients comprise a growing proportion of patients with coronary artery disease (CAD). Whereas prognostic scores are available to adjust for native CAD, there are no comparable scores for patients with previous CABG. METHODS: We studied 3,178 previous CABG patients (2,729 in a training set) who underwent cardiac catheterization. With a Cox model to develop relative weights in the training set, we created a graft index that adjusted native anatomy for territories with grafts free of significant (> or =75%) stenoses. Scaling the regression coefficients by the maximum coefficient created an index ranging from 0 to 100, where 100 was three-vessel CAD with no patent grafts. RESULTS: The graft index was significantly associated with all-cause death (chi-square = 121.9, p < 0.001). In combined models, the index was more strongly associated with all-cause death than either number of diseased vessels (chi-square = 68.0 and 1.7, respectively) or the Duke CAD index (chi-square = 54.3 and 9.5, respectively). In models for death using an independent validation set, the index was also associated more strongly than either native disease descriptors. In a model including other clinical variables, the graft index remained significantly associated with all-cause death (chi-square = 40.1, p < 0.001). CONCLUSIONS: For previous CABG patients, the Duke graft index was significantly more associated with prognosis than native anatomy alone and quantifies the effect of patent grafts on survival. This tool has the potential to help determine prognosis and inform the referral of post-CABG patients to repeat revascularization procedures.

Aged↗
PubMed2005

Outcomes following elective percutaneous coronary intervention without on-site surgical backup in a community hospital.

Despite guidelines to the contrary, limited numbers of elective percutaneous coronary intervention (PCI) procedures without on-site surgical backup are being performed, particularly in Europe and Canada. In the United States, many hospitals are considering establishing on-site surgical programs, in part to facilitate PCI. At a hospital with only off-site surgical backup, 562 elective PCI procedures were performed on 489 consecutive patients. Of these, 551 (98.0%) were successfully completed without major in-hospital complications; 5 patients (1.0%) had in-hospital complications, and 4 (0.8%) were urgently transferred. It is concluded that elective PCI with off-site surgical backup is feasible and safe for selected patients under specific conditions.

Angioplasty, Balloon, Coronary↗
PubMed2005

Reperfusion strategies for acute myocardial infarction in the elderly: benefits and risks.

The optimal reperfusion strategy in elderly patients with ST-segment elevation myocardial infarction (STEMI) remains a topic of debate. This lack of consensus stems from the exclusion or under-representation of the elderly in clinical trials. This review evaluates the available literature pertaining to reperfusion therapy for the treatment of STEMI in the elderly. We identified all published studies evaluating the effectiveness of thrombolytic therapy, primary percutaneous coronary intervention (PCI), or adjunctive therapies to reperfusion by conducting an electronic search of MEDLINE through December 2003. Meta-analysis of clinical trials suggests a survival benefit of thrombolytic therapy in the elderly with STEMI, whereas some observational studies have raised concerns about the lack of short-term benefit or possibility of harm with thrombolysis. However, most observational studies demonstrate improved intermediate-term survival with thrombolysis. In contrast, multiple clinical trials and observational studies indicate improved survival and low risk of stroke with primary PCI compared with thrombolysis in elderly patients with STEMI. Information on the efficacy of newer antithrombotic agents as adjunct to thrombolysis or primary PCI is scarce. Available data suggest an increased risk of intracerebral bleeding with the combination of a fibrin-specific agent and a glycoprotein IIb/IIIa receptor antagonist in patients >75 years of age. Clearly targeted large-scale clinical trials are needed to evaluate the relative merits of available reperfusion strategies as well as newer antithrombotic adjunctive therapies in the elderly with STEMI.

Aged↗
PubMed2005

Economic effects of prolonged clopidogrel therapy after percutaneous coronary intervention.

OBJECTIVES: This study examined the incremental cost-effectiveness of extending clopidogrel therapy from one month to one year after percutaneous coronary intervention (PCI) in an unselected, heterogeneous patient population. BACKGROUND: Clinical trials suggest that prolonging clopidogrel therapy for up to one year after PCI reduces downstream cardiac events. However, clopidogrel therapy is costly and may increase bleeding risk. METHODS: Using decision analysis, we compared the outcomes and cost of prolonging clopidogrel treatment from one month to one year after PCI with the alternative strategy of discontinuing therapy one month after the procedure. Event rates were based on 3,976 PCI patients who were treated between January 1999 and December 2001 at the Duke Medical Center and received no more than one month of clopidogrel after the procedure. Baseline characteristics and event rates were obtained from Duke clinical information systems. The effect of prolonged clopidogrel therapy on event rates was based on the Clopidogrel for the Reduction of Events During Observation (CREDO) trial per-protocol data. Unit costs and the effect of myocardial infarction (MI) on life expectancy were based on published sources. RESULTS: Extending clopidogrel therapy from one month to one year after PCI cost USD 879 per patient and reduced the risk of MI by 2.6%. Assuming MI decreases life expectancy by two years, prolonged therapy would cost USD 15,696 per year of life saved. Economic attractiveness of therapy varied with baseline risk, the effect of prolonged therapy on MI risk, and the price of clopidogrel. CONCLUSIONS: Prolonging clopidogrel therapy for one year after PCI is economically attractive, particularly in high-risk patients.

Aged↗
PubMed2005

Evaluation of the Medtronic (Driver) cobalt-chromium alloy coronary stent system.

The Driver Registry was a prospective, multicenter, nonrandomized study to evaluate the clinical safety and efficacy of the Driver cobalt-chromium alloy stent. Use of the cobalt-chromium alloy in place of stainless steel offers enhanced visibility and radial strength with thinner structural elements. The registry enrolled 298 patients with symptomatic ischemic heart disease attributable to de novo or restenotic nonstented native lesions of a single vessel amenable to percutaneous stenting. The primary composite end point was the incidence of major adverse cardiac events (death, myocardial infarction, emergency bypass surgery, or target lesion revascularization) 180 days after enrollment. Quantitative coronary angiography was performed before and after the index stent deployment and repeated at 6 months in 83 patients. Mean patient age was 62.6 years, mean reference vessel diameter was 3.07 mm before the procedure, and mean lesion length was 11.04 mm. Fifty-one patients received multiple stents. Angiographic success rate was 100% and procedural success rate was 98.3%. Cumulative incidence of major adverse cardiac events was 5.7% and target lesion revascularization was 3.4% at 180 days. In-stent late loss was 0.94 mm at 180 days, and no subacute stent thromboses were observed. This registry demonstrated the safety and efficacy of this novel coronary stent platform.

Chromium Alloys↗
PubMed2005

Late thrombosis following treatment of in-stent restenosis with drug-eluting stents after discontinuation of antiplatelet therapy.

Drug-eluting stent usage has become commonplace for the percutaneous treatment of de novo coronary lesions, but the safety and efficacy profile for their evolving usage in restenotic lesions is largely unknown. We report three cases of angiographically confirmed drug-eluting stent thrombosis following treatment of restenotic lesions that occurred late (193, 237, and 535 days) and shortly after interruption of antiplatelet therapy. All three patients suffered ST elevation myocardial infarction, and there was one death. Further studies are necessary to better define the associated risk and ideal duration of antiplatelet therapy necessary in this cohort of patients with restenotic lesions.

Adult↗
PubMed2004

Rationale and strategies for implementing community-based transfer protocols for primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction.

The focus for the initial approach to the treatment of acute ST-segment elevation myocardial infarction (STEMI) has shifted toward extending the benefits of mechanical reperfusion with primary percutaneous coronary intervention (PCI) to patients who present to community hospitals that have no interventional capabilities. Several randomized clinical trials have shown that transferring STEMI patients to tertiary centers for primary PCI leads to better outcomes than when fibrinolytic therapy is administered at community hospitals. Furthermore, potent pharmacologic reperfusion regimens that enhance early reperfusion of the infarct vessel before primary PCI may enhance the positive result of the transfer approach. Despite these promising findings, several obstacles have hindered the adoption of patient-transfer strategies in the U.S., including greater distances between community and tertiary hospitals, a lack of integrated emergency medical services, and the medical community's limited experience with centralized acute myocardial infarction (AMI) care networks. Nonetheless, the implementation of system-wide changes in the care of STEMI patients analogous to the creation of trauma networks could facilitate the creation and ongoing evaluation of dedicated patient transfer strategies and better early invasive care in the U.S. Within this context, a systematic, stepwise approach to the creation of AMI care networks and to the development of standard nomenclature and performance indicators is necessary to guide quality assurance monitoring and future research efforts as the care of STEMI patients is redefined. Consequently, this current evolution of reperfusion strategies has the potential to further reduce morbidity and mortality for patients presenting with STEMI.

Angioplasty, Balloon, Coronary↗
PubMed2004

Economic impact of drug-eluting stents on hospital systems: a disease-state model.

BACKGROUND: Drug-eluting intracoronary stents decrease restenosis and later revascularization. The US Department of Health and Human Services (HHS), recognizing the financial and clinical impact of this technology, recently proposed accelerated reimbursement to hospitals. METHODS AND RESULTS: A disease state-transition computer model simulated the clinical and economic consequences to hospitals of drug-eluting stents over 5 years. Model parameters combined information from a longitudinal clinical database, a hospital cost-accounting system, and a survey instrument. Simulations were repeated 1000 times for each set of parameters. With 85% of stent procedures shifted to drug-eluting stents in the first year of availability, the mean number of repeat revascularizations dropped by 60.4% at year 5. With no changes in reimbursement policy, a hospital with a catheterization laboratory volume of 3112 patients yearly converted from a 2.01 million dollars (M) annual profit to an 8.10 M dollars loss in the first year (95% CI 8.09 M dollars to 8.12 M dollars) and 8.7 M dollars annual losses in later years. This represented an overall change in cash flow of 55.71 M dollars (95% CI 55.66 M dollars to 55.76 M dollars) away from the hospital over 5 years. The incremental reimbursement proposed by HHS reduced this loss to 4.75 M dollars in the first year and to 5.6 M dollars annually thereafter. In sensitivity analyses, the conversion of patients from bypass surgery to drug-eluting stents was the largest driver of overall cash flow shifts. CONCLUSIONS: Although Medicare has proposed to increase reimbursement to ease the impact of drug-eluting stents on hospitals, this increase will not totally offset the costs.

Angioplasty, Balloon, Coronary↗