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Biomedical subjects

Michael S Lauer

Publications and source records attributed to Michael S Lauer.

At least 73 records · Page 4Linked to original sources
PubMed2003

Value of exercise capacity and heart rate recovery in older people.

OBJECTIVES: To evaluate the prognostic value in older adults of two predictors of mortality: impaired functional capacity and an attenuated heart rate recovery. SETTING: Academic medical center. DESIGN: Prospective study with mean 3.7 years follow-up. PARTICIPANTS: Seven thousand three hundred fifty-four adults aged 65 and older consecutively referred for exercise testing between 1990 and 1999. Patients with heart failure, valvular disease, atrial fibrillation, and pacemakers were excluded. MEASUREMENTS: The primary endpoint was all-cause mortality. Impaired functional capacity was defined as the peak exercise workload in the lowest quintile of metabolic equivalents achieved according to prespecified strata of age and sex. Heart rate recovery was defined as the fall in heart rate during the first minute after exercise and was abnormal if 12 or fewer beats per minute, except for patients undergoing stress echocardiography, in which case 18 or fewer beats per minute was abnormal. RESULTS: There were 842 deaths. Patients with impaired functional capacity were at increased risk for death (23% vs 9%, hazard ratio (HR) = 2.7, 95% confidence interval (CI) = 2.2-3.1, P <.0001) as were patients with an abnormal heart rate recovery (17% vs 9%, HR = 2.0, 95% CI = 1.8-2.3, P <.0001). After adjusting for age, sex, coronary history, and other confounders, impaired functional capacity (adjusted HR = 2.1, 95% CI = 1.8-2.4) and an abnormal heart rate recovery (adjusted HR = 1.5, 95% CI = 1.3-1.7) independently predicted death. No interactions between these two variables with age were noted. CONCLUSIONS: In older patients, impaired functional capacity and heart rate recovery were independent predictors of death.

Aged↗
PubMed2003

Heart rate recovery following maximal exercise testing as a predictor of cardiovascular disease and all-cause mortality in men with diabetes.

OBJECTIVE: Heart rate recovery (HRR) is an independent prognostic indicator for cardiovascular disease (CVD) and all-cause mortality in healthy men. We examined the association of HRR to CVD-related and all-cause mortality in men with diabetes. RESEARCH DESIGN AND METHODS: In this cohort study we examined 2,333 men with documented diabetes (mean age 49.4 years) that had baseline 5-min HRR measurement following maximal exercise (heart rate(peak) - heart rate(5 min of recovery)) at The Cooper Clinic, Dallas, TX. We identified HRR quartiles as quartile 1 <55, quartile 2 55-66, quartile 3 67-75, and quartile 4 >75 bpm. Hazard ratios (HRs) for cardiovascular and all-cause death were adjusted for age, cardiorespiratory fitness, resting heart rate, fasting blood glucose, BMI, smoking habit, alcohol consumption, total cholesterol, triglyceride, and history of CVD at baseline. RESULTS: During a median of 14.9 years follow-up, there were 142 deaths that were considered CVD related and 287 total deaths. Compared with men in the highest quartile of HRR, adjusted HRs in the first, second, and third quartiles were 2.0 (95% CI 1.1-3.8), 1.5 (0.8-2.7), and 1.5 (0.9-2.8), respectively, for cardiovascular death (P for trend < 0.001). Similarly, for all-cause death, adjusted HRs in the first, second, and third quartiles were 2.0 (1.3-3.2), 1.5 (1.0-2.3), and 1.5 (1.1-2.3) (P for trend < 0.001). CONCLUSIONS: Among men with diabetes, a decreased HRR, even measured as long as 5 min after recovery, was independently predictive of cardiovascular and all-cause death.

Adult↗
PubMed2003

Who should be taking aspirin to prevent coronary events?

The decision to prescribe aspirin to prevent a coronary event is not straightforward, and requires physicians to balance the risk of a coronary event with the risk of adverse events from aspirin. Although evidence-based medicine shows the way, it does not answer all the questions, especially for patients at intermediate risk.

Aged↗
PubMed2003

Prognostic value of normal exercise and adenosine (99m)Tc-tetrofosmin SPECT imaging: results from the multicenter registry of 4,728 patients.

UNLABELLED: Event rates associated with a normal or low-risk myocardial perfusion SPECT imaging study have been shown by numerous investigators to be associated with <1%/y of follow-up. Thus, the aim of this study was to evaluate the prognostic value of a normal (99m)Tc-tetrofosmin study in a geographically diverse registry of patients undergoing stress myocardial perfusion SPECT. A total of 4,728 consecutively tested patients who underwent stress (99m)Tc-tetrofosmin SPECT at 5 U.S. hospitals were included in this series. METHODS: Patients were monitored for the occurrence of major cardiac events and hospitalizations. Uniform methods of data collection and standardized epidemiologic methods for follow-up were used at all centers. We used a risk-adjusted, Cox proportional hazards model to assess time to cardiac death. RESULTS: Of the 4,728 patients, one third underwent adenosine stress SPECT and two thirds underwent treadmill exercise. The observed annualized survival rate for those patients with a normal (99m)Tc-tetrofosmin study was 0.6%. Similarly, excellent survival rates were noted for the male and female subsets of this population as well as for patients who could exercise and for those undergoing pharmacologic stress testing. Compared with prior published outcomes studies on stress (201)Tl or (99m)Tc-sestamibi SPECT, the overall survival rates were similar and ranged from 99.3% to 99.7%. CONCLUSION: Results from this large multicenter registry provide further supportive evidence that the excellent prognosis associated with a normal SPECT scan is independent of the radiopharmaceutical used.

Adenosine↗
PubMed2002

Association of educational status with heart rate recovery: a population-based propensity analysis.

PURPOSE: An abnormally attenuated heart rate recovery after exercise is a predictor of mortality that is thought to reflect decreased parasympathetic activity. Lower educational level may be associated with automatic imbalance. We sought to assess the association of educational level with heart rate recovery. SUBJECTS AND METHODS: Among 5246 healthy adults from a population-based cohort who underwent exercise testing, 874 (17%) did not graduate from high school, 1823 (35%) completed high school, and 2549 (49%) attended at least some college. An abnormal heart rate recovery was defined as a difference of </=42 beats per minute between the peak heart rate and that after 2 minutes of recovery. Propensity scores were used to account for differences by educational status. RESULTS: An abnormal heart rate recovery was more common among adults who did not graduate from high school compared with those who attended at least some college (50% [440/874] vs. 28% [701/2549]; odds ratio [OR]: 2.7; 95% confidence interval [CI]: 2.3 to 3.1; P <0.001). After using propensity scores, lower educational status remained associated with an abnormal heart rate recovery (OR = 1.9; 95% CI: 1.6 to 2.4; P <0.001). During 12-years of follow-up, there were 327 deaths. Poor educational status was associated with greater mortality (9% [80/874] vs. 6% [247/4372]; unadjusted hazard ratio [HR] = 1.9; 95% CI: 1.4 to 2.5; P <0.001). However, after accounting for age, sex, and heart rate recovery, educational status was a weaker predictor (HR = 1.3; 95% CI: 1.0 to 1.7). CONCLUSIONS: Educational status is independently associated with an abnormal heart rate recovery.

Adult↗
PubMed2002

The prognostic value of estimated creatinine clearance alongside functional capacity in ambulatory patients with chronic congestive heart failure.

OBJECTIVES: The goal of this study was to determine the prognostic significance of estimated creatinine clearance (CrCl) in relation to 6-min walk distance in ambulatory patients with congestive heart failure (HF). BACKGROUND: Although measurement of renal function is integral to the management of chronic congestive HF, its prognostic implications are not well described and have not been formally evaluated relative to measures of functional capacity. METHODS: We analyzed outcomes of the 585 participants of the 6-min walk substudy of the Digitalis Investigation Group (DIG) trial. The CrCl was estimated using the Cockcroft-Gault equation. Predictors of all-cause mortality were identified using semiparametric Cox proportional hazards regression and completely parametric hazard analyses. RESULTS: Most subjects (85%) were New York Heart Association functional class II and III. Mean age was 65 (+/-12) years and mean ejection fraction (EF) 35% (+/-13%). There were 153 (26%) deaths during a median of 2.6 years of follow-up. Mortality by increasing quartiles of estimated CrCl was 37% (18 to 48 ml/min), 29% (47 to 64 ml/min), 18% (64 to 86 ml/min), and 21% (86 to 194 ml/min) with corresponding hazard ratios (HRs) relative to the top quartile of 2.1 (95% confidence interval [CI], 1.4 to 3.3), 1.6 (95% CI, 1.0 to 2.5), and 0.9 (95% CI, 0.5 to 1.5), respectively. In Cox regression analyses, independent predictors of mortality were estimated CrCl (adjusted HR [quartile 1:quartile 4] 1.5; 95% CI, 1.1 to 2.1), 6-min walk distance < or =262 m [adjusted HR, 1.63; 95% CI, 1.12 to 2.27]), EF, recent hospitalization for worsening HF, and need for diuretic treatment. Parametric (hazard) analysis confirmed consistent effects of estimated CrCl on mortality in several subgroups including that of patients with EF >45%. CONCLUSION: In ambulatory patients with congestive HF, estimated CrCl predicts all-cause mortality independently of established prognostic variables.

Aged↗
PubMed2002

Cardiologist on trial: reflections on credible evidence.

During a recent medical malpractice lawsuit brought against me, I was forced to confront the fundamentally different ways in which physician scientists and litigation attorneys assess and utilize clinical evidence. The plaintiff alleged that I failed to diagnose myocardial sarcoid in her husband and that my failure to do so resulted in her husband's death. Her case was based largely on the testimony of one expert witness, who had been involved in more than 300 other medical malpractice actions, and who had never performed any kind of peer-reviewed research or systematic reviews on myocardial sarcoid. None of the evidence that he presented against me was based on randomized trials, high-quality observational studies or even published practice guidelines, yet the judge saw fit to introduce his testimony as valid evidence to be considered by a lay jury. I conclude by proposing a voluntary system whereby expert witnesses would subject their reports to external peer review, much as is done at top-tier medical journals. Those experts who are able to have their reports pass peer review would be presented to the jury as having a greater level of credibility.

Adult↗
PubMed2002

Use of the logical analysis of data method for assessing long-term mortality risk after exercise electrocardiography.

BACKGROUND: Logical Analysis of Data is a methodology of mathematical optimization on the basis of the systematic identification of patterns or "syndromes." In this study, we used Logical Analysis of Data for risk stratification and compared it to regression techniques. METHODS AND RESULTS: Using a cohort of 9454 patients referred for exercise testing, Logical Analysis of Data was applied to identify syndromes based on 20 variables. High-risk syndromes were patterns of up to 3 findings associated with >5-fold increase in risk of death, whereas low-risk syndromes were associated with >5-fold decrease. Syndromes were derived on a randomly derived training set of 4722 patients and validated in 4732 others. There were 15 high-risk and 26 low-risk syndromes. A risk score was derived based on the proportion of possible high risk and low risk syndromes present. A value > or =0, meaning the same or a greater proportion of high-risk syndromes, was noted in 979 patients (21%) in the validation set and was predictive of 5-year death (11% versus 1%, hazard ratio 8.3, 95% CI 5.9 to 11.6, P<0.0001), accounting for 67% of events. Calibration of expected versus observed death rates based on Logical Analysis of Data and Cox regression showed that both methods performed very well. CONCLUSION: Using the Logical Analysis of Data method, we identified subsets of patients who had an increased risk and who also accounted for the majority of deaths. Future research is needed to determine how best to use this technique for risk stratification.

Cardiovascular Diseases↗
PubMed2002

Troponin T levels in patients with acute coronary syndromes, with or without renal dysfunction.

BACKGROUND: Among patients with suspected acute coronary syndromes, cardiac troponin T levels have prognostic value. However, there is concern that renal dysfunction may impair the prognostic value, because cardiac troponin T may be cleared by the kidney. METHODS: We analyzed the outcomes in 7033 patients enrolled in the Global Use of Strategies to Open Occluded Coronary Arteries IV trial who had complete base-line data on troponin T levels and creatinine clearance rates. The troponin T level was considered abnormal if it was 0.1 ng per milliliter or higher, and creatinine clearance was assessed in quartiles. The primary end point was a composite of death or myocardial infarction within 30 days. RESULTS: Death or myocardial infarction occurred in 581 patients. Among patients with a creatinine clearance above the 25th percentile value of 58.4 ml per minute, an abnormally elevated troponin T level was predictive of an increased risk of myocardial infarction or death (7 percent vs. 5 percent; adjusted odds ratio, 1.7; 95 percent confidence interval, 1.3 to 2.2; P<0.001). Among patients with a creatinine clearance in the lowest quartile, an elevated troponin T level was similarly predictive of increased risk (20 percent vs. 9 percent; adjusted odds ratio, 2.5; 95 percent confidence interval, 1.8 to 3.3; P<0.001). When the creatinine clearance rate was considered as a continuous variable and age, sex, ST-segment depression, heart failure, previous revascularization, diabetes mellitus, and other confounders had been accounted for, elevation of the troponin T level was independently predictive of risk across the entire spectrum of renal function. CONCLUSIONS: Cardiac troponin T levels predict short-term prognosis in patients with acute coronary syndromes regardless of their level of creatinine clearance.

Abciximab↗
PubMed2002

Survival after aortic valve replacement for severe aortic stenosis with low transvalvular gradients and severe left ventricular dysfunction.

OBJECTIVE: We sought to assess whether aortic valve replacement (AVR) among patients with severe aortic stenosis (AS), severe left ventricular (LV) dysfunction and a low transvalvular gradient (TVG) is associated with improved survival. BACKGROUND: The optimal management of patients with severe AS with severe LV dysfunction and a low TVG remains controversial. METHODS: Between 1990 and 1998, we evaluated 68 patients who underwent AVR at our institution (AVR group) and 89 patients who did not undergo AVR (control group), with an aortic valve area < or = 0.75 cm(2), LV ejection fraction < or = 35% and mean gradient < or = 30 mm Hg. Using propensity analysis, survival was compared between a cohort of 39 patients in the AVR group and 56 patients in the control group. RESULTS: Despite well-matched baseline characteristics among propensity-matched patients, the one- and four-year survival rates were markedly improved in patients in the AVR group (82% and 78%), as compared with patients in the control group (41% and 15%; p < 0.0001). By multivariable analysis, the main predictor of improved survival was AVR (adjusted risk ratio 0.19, 95% confidence interval 0.09 to 0.39; p < 0.0001). The only other predictors of mortality were age and the serum creatinine level. CONCLUSIONS: Among select patients with severe AS, severe LV dysfunction and a low TVG, AVR was associated with significantly improved survival.

Adult↗
PubMed2002

Development and validation of a simple exercise test score for use in women with symptoms of suspected coronary artery disease.

BACKGROUND: Recently revised American College of Cardiology/American Heart Association guidelines for exercise electrocardiography (ExECG) have suggested that ExECG scores be used to assist in management decisions in patients with suspected coronary artery disease (CAD). METHODS: We used 442 women who underwent both ExECG and coronary angiography (CAD > or =1 lesion with > or =50% stenosis; CAD prevalence was 32%) to derive an ExECG score including clinical and ExECG variables. By use of logistic regression analysis, variables were selected and relative weights were determined. Variable codes multiplied by respective weights were summed to produce a final ExECG score. The score was validated in separate populations concerning angiographic as well as prognostic end points. RESULTS: Clinical variables selected and their weights included age (5), symptoms (2), diabetes (2), smoking (2), and estrogen status (1). ExECG variables selected and their weights included ST depression (2), exercise heart rate (4), and Duke Angina Index (3). For the validation group, score ranges are shown with the prevalence of CAD: <20 = 0/5 or 0%, 20-29 = 3/26 or 11%, 30-39 = 20/56 or 36%, 40-49 = 33/81 or 41%, 50-59 = 24/49 or 49%, 60-69 = 22/32 or 69%, and >70 = 7/7 or 100%. Frequency of death within 3 predetermined subgroups was as follows: low <40 = 3/1237 (0.2%), intermediate 40-60 = 9/383 (2.3%), high >60 = 4/54(7%); P<.0001. CONCLUSION: A simple ExECG score was developed for use specifically in women. When evaluated in separate cohorts, the score stratified women with suspected coronary disease into groups with a gradually increasing frequency of coronary disease and death.

Adult↗