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Biomedical subjects

Brahmajee K Nallamothu

Publications and source records attributed to Brahmajee K Nallamothu.

At least 19 recordsLinked to original sources
PubMed2006

Microvolt T-wave alternans identifies patients with ischemic cardiomyopathy who benefit from implantable cardioverter-defibrillator therapy.

OBJECTIVES: This study sought to assess whether implantable cardioverter-defibrillators (ICDs) have different mortality benefits among patients with ischemic cardiomyopathy who screen negative and non-negative (positive and indeterminate) for microvolt T-wave alternans (MTWA). BACKGROUND: Microvolt T-wave alternans has been proposed as an effective tool for risk stratification. However, no studies have examined whether ICD benefits differ by MTWA group. METHODS: We developed a prospective cohort of 768 patients with ischemic cardiomyopathy (left ventricular ejection fraction < or =35%) and no prior sustained ventricular arrhythmia, of which 392 (51%) received ICDs. The mean follow-up time was 27 +/- 12 months. Propensity scores for ICD implantation based on the variables most likely to influence defibrillator implantation were developed for each MTWA cohort. Multivariable Cox analyses that controlled for propensity score, demographics, and clinical variables evaluated the degree to which ICDs decreased mortality risk for each MTWA group. RESULTS: We identified 514 (67%) patients with a non-negative MTWA test result. After multivariable adjustment, ICDs were associated with lower all-cause mortality in MTWA-non-negative patients (hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.27 to 0.76, p = 0.003) but not in MTWA-negative patients (HR 0.85, 95% CI 0.33 to 2.20, p = 0.73) (for interaction, p = 0.04), with the mortality benefit in MTWA-non-negative patients largely mediated through arrhythmic mortality reduction (HR 0.30, 95% CI 0.13 to 0.68, p = 0.004). The number needed to treat with an ICD for 2 years to save 1 life was 9 among MTWA-non-negative patients and 76 among MTWA-negative patients. CONCLUSIONS: In patients with ischemic cardiomyopathy and no prior history of ventricular arrhythmia, mortality reduction with ICD implantation differs by MTWA status, with implications for risk stratification and health policy.

Aged↗
PubMed2006

Strategies for reducing the door-to-balloon time in acute myocardial infarction.

BACKGROUND: Prompt reperfusion treatment is essential for patients who have myocardial infarction with ST-segment elevation. Guidelines recommend that the interval between arrival at the hospital and intracoronary balloon inflation (door-to-balloon time) during primary percutaneous coronary intervention should be 90 minutes or less. However, few hospitals meet this objective. We sought to identify hospital strategies that were significantly associated with a faster door-to-balloon time. METHODS: We surveyed 365 hospitals to determine whether each of 28 specific strategies was in use. We used hierarchical generalized linear models and data on patients from the Centers for Medicare and Medicaid Services to determine the association between hospital strategies and the door-to-balloon time. RESULTS: In multivariate analysis, six strategies were significantly associated with a faster door-to-balloon time. These strategies included having emergency medicine physicians activate the catheterization laboratory (mean reduction in door-to-balloon time, 8.2 minutes), having a single call to a central page operator activate the laboratory (13.8 minutes), having the emergency department activate the catheterization laboratory while the patient is en route to the hospital (15.4 minutes), expecting staff to arrive in the catheterization laboratory within 20 minutes after being paged (vs. >30 minutes) (19.3 minutes), having an attending cardiologist always on site (14.6 minutes), and having staff in the emergency department and the catheterization laboratory use real-time data feedback (8.6 minutes). Despite the effectiveness of these strategies, only a minority of hospitals surveyed were using them. CONCLUSIONS: Several specific hospital strategies are associated with a significant reduction in the door-to-balloon time in the management of myocardial infarction with ST-segment elevation.

Angioplasty, Balloon, Coronary↗
PubMed2006

Hospital delays in reperfusion for ST-elevation myocardial infarction: implications when selecting a reperfusion strategy.

BACKGROUND: It has been suggested that the survival benefit associated with primary percutaneous coronary intervention (PPCI) in ST-segment elevation myocardial infarction may be attenuated if door-to-balloon (DB) time is delayed by >1 hour beyond door-to-needle (DN) times for fibrinolytic therapy. Whereas DB times are rapid in randomized trials, they are often prolonged in routine practice. We hypothesized that in clinical practice, longer DB-DN times would be associated with higher mortality rates and reduced PPCI survival advantage. We also hypothesized that in addition to PPCI delays, patient risk factors would significantly modulate the relative survival advantage of PPCI over fibrinolysis. METHODS AND RESULTS: DB-DN times were calculated by subtracting median DN time from median DB time at a hospital using data from 192,509 patients at 645 National Registry of Myocardial Infarction hospitals. Hierarchical models that adjusted simultaneously for both patient-level risk factors and hospital-level covariates were used to evaluate the relationship between PCI-related delay, patient risk factors, and in-hospital mortality. Longer DB-DN times were associated with increased mortality (P<0.0001). The DB-DN time at which mortality rates with PPCI were no better than that of fibrinolysis varied considerably depending on patient age, symptom duration, and infarct location. CONCLUSIONS: As DB-DN times increase, the mortality advantage of PPCI over fibrinolysis declines, and this advantage varies considerably depending on patient characteristics. As indicated in the American College of Cardiology/American Heart Association guidelines, both the hospital-based PPCI-related delay (DB-DN time) and patient characteristics should be considered when a reperfusion strategy is selected.

Aged↗
PubMed2006

Hospital quality for acute myocardial infarction: correlation among process measures and relationship with short-term mortality.

CONTEXT: The Centers for Medicare & Medicaid Services (CMS) and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) measure and report quality process measures for acute myocardial infarction (AMI), but little is known about how these measures are correlated with each other and the degree to which inferences about a hospital's outcomes can be made from its performance on publicly reported processes. OBJECTIVE: To determine correlations among AMI core process measures and the degree to which they explain the variation in hospital-specific, risk-standardized, 30-day mortality rates. DESIGN, SETTING, AND PARTICIPANTS: We assessed hospital performance in the CMS/JCAHO AMI core process measures using 2002-2003 data from 962 hospitals participating in the National Registry of Myocardial Infarction (NRMI) and correlated these measures with each other and with hospital-level, risk-standardized, 30-day mortality rates derived from Medicare claims data. MAIN OUTCOME MEASURES: Hospital performance on AMI core measures; hospital-specific, risk-standardized, 30-day mortality rates for AMI patients aged 66 years or older. RESULTS: We found moderately strong correlations (correlation coefficients > or =0.40; P values <.001) for all pairwise comparisons between beta-blocker use at admission and discharge, aspirin use at admission and discharge, and angiotensin-converting enzyme inhibitor use, and weaker, but statistically significant, correlations between these medication measures and smoking cessation counseling and time to reperfusion therapy measures (correlation coefficients <0.40; P values <.001). Some process measures were significantly correlated with risk-standardized, 30-day mortality rates (P values <.001) but together explained only 6.0% of hospital-level variation in risk-standardized, 30-day mortality rates for patients with AMI. CONCLUSIONS: The publicly reported AMI process measures capture a small proportion of the variation in hospitals' risk-standardized short-term mortality rates. Multiple measures that reflect a variety of processes and also outcomes, such as risk-standardized mortality rates, are needed to more fully characterize hospital performance.

Aged↗
PubMed2006

Prognostic utility of microvolt T-wave alternans in risk stratification of patients with ischemic cardiomyopathy.

OBJECTIVES: The purpose of this study was to assess if microvolt T-wave alternans (MTWA) is an independent predictor of mortality in patients with ischemic cardiomyopathy. BACKGROUND: Microvolt T-wave alternans has been proposed as an effective tool for identifying high-risk patients with ischemic cardiomyopathy who are likely to benefit from implantable cardioverter-defibrillator (ICD) therapy. However, earlier studies have been limited in their ability to control for baseline differences between MTWA-negative and -non-negative (positive and indeterminate) patients. METHODS: We enrolled 768 consecutive patients with ischemic cardiomyopathy (left ventricular ejection fraction < or =35%) and no prior history of ventricular arrhythmia. All patients underwent baseline MTWA testing and were classified as MTWA negative or non-negative. Multivariable Cox regression analyses, stratified by ICD status, were used to determine the association between MTWA testing and mortality after adjusting for demographic, clinical, and treatment differences between MTWA-negative and -non-negative patients. RESULTS: We identified 514 (67%) patients with a non-negative MTWA test. After multivariable adjustment, a non-negative MTWA test was associated with a significantly higher risk for all-cause (stratified hazard ratio [HR] = 2.24 [95% confidence interval 1.34 to 3.75]; p = 0.002) and arrhythmic mortality (stratified HR = 2.29 [1.00 to 5.24]; p = 0.049) but not for nonarrhythmic mortality (stratified HR = 1.77 [0.84 to 3.74]; p = 0.13). In subgroup analyses, a non-negative MTWA test was also associated with a higher risk for all-cause mortality in patients with ejection fractions < or =30% (stratified HR = 2.10 [1.18 to 3.73]; p = 0.01) and after excluding those with indeterminate MTWA tests (stratified HR = 2.08 [1.18 to 3.66]; p = 0.01). CONCLUSIONS: Microvolt T-wave alternans is a strong and independent predictor of all-cause and arrhythmic mortality in patients with ischemic cardiomyopathy.

Aged↗
PubMed2006

Regionalization of ST-segment elevation acute coronary syndromes care: putting a national policy in proper perspective.

A uniform policy for regionalization of ST-segment elevation myocardial infarction (STEMI) care raises several concerns. Transferring all STEMI patients to obtain primary percutaneous coronary intervention (PCI) may be less effective than transferring only high-risk STEMI patients. Delays in time to treatment >60 min associated with transferring patients for primary PCI may result in increased mortality for the average patient as compared with providing immediate fibrinolytic therapy at their initial hospital; yet more than 95% of patients transferred for primary PCI in the U.S. exceed this 60-min benchmark. Superior outcomes associated with treatment at higher-volume regional STEMI centers are inconsistent among centers, and there is no direct evidence that patients will benefit by a transfer to a high-volume hospital from a low-volume hospital. Published data suggest as many as 800 PCI patients would need to be transferred to a high-volume PCI hospital to avoid a single death at a low-volume PCI hospital. Although European randomized trial data suggest transferring patients with STEMI for primary PCI may be superior to immediate fibrinolytic therapy, these findings are unlikely to generalize to the U.S. health care system given size, geography, and organization. ST segment elevation myocardial infarction care regionalization would require a massive redistribution of health care resources, depriving several hospitals of advanced cardiac care facilities, expertise, and associated revenue. Clearer evidence of the benefits and discussion of potential harms are needed before adopting a national STEMI regionalization policy.

Acute Disease↗
PubMed2006

Driving times and distances to hospitals with percutaneous coronary intervention in the United States: implications for prehospital triage of patients with ST-elevation myocardial infarction.

BACKGROUND: The success of prehospital triage protocols for patients with ST-elevation myocardial infarction (STEMI) will depend, in part, on how patients are geographically distributed around hospitals that perform percutaneous coronary intervention (PCI). Accordingly, we determined the proportion of the adult population in the United States with timely access to PCI hospitals using driving times and distances. METHODS AND RESULTS: We performed a cross-sectional study using hospital-level data from the American Hospital Association Annual Survey and Census tract-level data on adults 18 years of age or older from the 2000 United States Census. Our aims were to determine the proportion of the adult population who (1) lived within 60 minutes of a PCI hospital and (2) had additional transport times within 30 minutes if directly referred to a PCI hospital as opposed to a closer, non-PCI hospital. Median times and distances to the closest PCI hospital were 11.3 (interquartile range [IQR] 5.7 to 28.5) minutes and 7.9 (IQR 3.5 to 22.4) miles, respectively. A total of 79.0% of the adult population lived within 60 minutes of a PCI hospital. Among those with a non-PCI hospital as their closest facility, 74.0% required additional transport times of <30 minutes if directly referred to a PCI hospital as opposed to the non-PCI hospital. These estimates varied substantially across regions and urban, suburban, and rural Census tracts. CONCLUSIONS: Nearly 80% of the adult population in the United States lived within 60 minutes of a PCI hospital in 2000. Even among those living closer to non-PCI hospitals, almost three fourths would experience <30 minutes of additional delay with direct referral to a PCI hospital, which suggests that such a strategy might be feasible for these individuals.

Angioplasty, Balloon, Coronary↗
PubMed2006

Contribution of infection to increased mortality in women after cardiac surgery.

BACKGROUND: Women have higher mortality rates after coronary artery bypass graft (CABG) surgery compared with men. Explanations for this sex difference are controversial. The objective of this study was to assess whether infection contributes to the increased risk of mortality in women. METHODS: We conducted a cohort study of 9218 Michigan Medicare beneficiaries hospitalized for CABG surgery. The prevalence of infection at any site during hospitalization was determined. Patients were followed up for 100 days after surgery to assess vital status. Analyses were conducted using proportional hazards regression and population attributable risk. RESULTS: Women hospitalized for CABG surgery were more likely to have an infection than men (16.1% vs 9.8%, P<.001), regardless of age, race, type of admission, hospital volume, or presence of comorbidities. Infections of the respiratory tract, urinary tract, digestive tract, and skin and subcutaneous tissue were more common in women than in men. The risk of death in men increased 3-fold with infection, whereas the risk in women increased 1.8-fold. The interaction between infection and sex on mortality was significant after adjusting for age, type of admission, and presence of comorbidities (P = .008). The unadjusted percentage of deaths attributable to female sex was 13.9%, which decreased to 0.3% when adjusted for infection. Of the excess deaths in women, 96% could be accounted for by the differential distribution of infection between the sexes. CONCLUSION: The increased risk of mortality after CABG surgery in women may be explained by underlying differences in the prevalence of infection among men and women.

Aged↗
PubMed2006

Relation between hospital specialization with primary percutaneous coronary intervention and clinical outcomes in ST-segment elevation myocardial infarction: National Registry of Myocardial Infarction-4 analysis.

BACKGROUND: Hospitals with primary percutaneous coronary intervention (PPCI) capability may choose to predominately offer PPCI to their patients with ST-segment elevation myocardial infarction (STEMI), or they may selectively offer PPCI or fibrinolytic therapy based on patient and hospital-level factors. Whether a greater level of hospital specialization with PPCI is associated with better quality of care is unknown. METHODS AND RESULTS: We analyzed data from the National Registry of Myocardial Infarction-4 to compare in-hospital mortality and times to treatment in STEMI across different levels of hospital specialization with PPCI. We divided 463 hospitals into quartiles of PPCI specialization based on the relative proportion of reperfusion-treated patients who underwent PPCI (< or =34.0%, >34.0 to 62.5%, >62.5 to 88.5%, >88.5%). Hierarchical multivariable regression assessed whether PPCI specialization was associated with better outcomes, after adjusting for patient and hospital characteristics, including PPCI volume. We found that greater PPCI specialization was associated with a lower relative risk of in-hospital mortality in patients treated with PPCI (adjusted relative risk comparing the highest and lowest quartiles, 0.64; P=0.006) but not in those treated with fibrinolytic therapy. Compared with patients at hospitals in the lowest quartile of PPCI specialization, adjusted door-to-balloon times in the highest quartile were significantly shorter (99.6 versus 118.3 minutes; P<0.001), and the likelihood of door-to-balloon times exceeding 90 minutes was significantly lower (relative risk, 0.78; P<0.001). Adjusting for PPCI specialization diminished the association between PPCI volume and clinical outcomes. CONCLUSIONS: Greater specialization with PPCI is associated with lower in-hospital mortality and shorter door-to-balloon times in STEMI patients treated with PPCI.

Angioplasty, Balloon↗
PubMed2006

Broken bodies, broken hearts? Limitations of the trauma system as a model for regionalizing care for ST-elevation myocardial infarction in the United States.

Many cardiovascular experts have called for the creation of specialized myocardial infarction centers and networks in the United States analogous to the current model for major trauma. Patients suffering ST-elevation myocardial infarction (STEMI) and trauma share an essential feature that makes the argument for regionalization persuasive: rapid triage and treatment by highly trained personnel improve survival in both conditions. Despite this similarity, however, the trauma system may be limited as a model for regionalizing STEMI care. First, the development of trauma systems has been hindered by the struggle for sufficient and stable funding, competing interests among individual stakeholders, and the overall lack of desire for state-sponsored healthcare planning in the United States. These same obstacles would need to be overcome if STEMI care is regionalized. Second, unique characteristics related to STEMI care, such as its varied clinical presentation and more lucrative reimbursement, will create new challenges. In this article, we briefly review the current status of trauma systems in the United States and describe why the regionalization of STEMI care may require different methods of healthcare organization.

Electrocardiography↗
PubMed2006

Allogeneic blood transfusions explain increased mortality in women after coronary artery bypass graft surgery.

BACKGROUND: Postoperative mortality is greater in women than men after coronary artery bypass graft surgery. Because allogeneic blood transfusions are more common in women and have been associated with immunomodulation, the impact of transfusion on sex differences in infection and mortality was examined. METHODS: A cohort study was conducted using Michigan Medicare beneficiaries who had undergone coronary artery bypass graft surgery. Information was used regarding allogeneic blood transfusion, infection, and mortality within the 100-day period after surgery. RESULTS: Blood transfusions were more common in women than in men (88.2%, 95% CI 87.1%-89.2% vs 66.7%, 95% CI 65.5%-67.9%). Patients who received transfused blood were more likely to have an infection than patients who did not (14.6%, 95% CI 13.8%-15.5% vs 4.9%, 95% CI 4.1%-5.9%). There was a dose-response relationship between the number of units of whole blood or packed red cells received and the prevalence of infection (P = .035). The unadjusted risk of mortality attributable to female sex was 13.9% (95% CI 8.1%-19.6%), but was no longer statistically significant when adjusted for blood transfusion (population attributable risk 0.6%, 95% CI -6.0% to 6.6%). Patients who received a transfusion were 5.6 times as likely to die within 100 days after surgery as those who did not receive a transfusion (95% CI 3.7-8.6). CONCLUSION: The increased risk of mortality in women after bypass surgery may be explained by transfusion-related immunosuppression.

Blood Transfusion↗
PubMed2005

Effect of statin use in patients with acute coronary syndromes and a serum low-density lipoprotein<or=80 mg/dl.

We identified 155 patients who were admitted with an acute coronary syndrome and a low-density lipoprotein cholesterol level<or=80 mg/dl and were not on statin therapy at hospital admission. The relation between statin therapy at discharge and clinical outcome was evaluated in these patients. Compared with patients who were not discharged on statins, those who were had a lower incidence of death, reinfarction, or stroke at 6 months (29.0% vs 9.5%, p=0.005). These results suggest that patients who have an acute coronary syndrome and a low-density lipoprotein cholesterol level<or=80 mg/dl in the absence of statin therapy may benefit from such therapy at discharge.

Acute Disease↗