Biomedical subjects

Martin St John Sutton

Publications and source records attributed to Martin St John Sutton.

23 records · Page 2Linked to original sources

PubMed2002

Prevention of Left Ventricular Remodeling After Myocardial Infarction.

Postinfarction left ventricular remodeling begins early after acute myocardial infarction and may continue for months to years afterward. Early re-establishment of flow in the occluded artery is associated with smaller left ventricular cavity volumes and reduced remodeling. Acute percutaneous coronary intervention (PCI) or thrombolytic therapy (for patients more than 1 hour away from a catheterization facility) as early as possible after symptoms is critical. Late reperfusion (PCI more than 12 hours after infarction) may prove useful, and this will be determined by the results of ongoing clinical trials. Recurrent MI is reduced by antiplatelet agents (aspirin in most patients) and by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Intravenous nitroglycerin may limit early (initial 24 hours) dilatation following infarction, but long-term use in asymptomatic patients is not efficacious. Beta- adrenergic receptor antagonists and angiotensin-converting enzyme (ACE) inhibitors have independent efficacy in attenuating the early and late phases of remodeling. The combined use of a beta-blocker and an ACE inhibitor has greater efficacy than either agent alone, provided they are tolerated hemodynamically. Although angiotensin II receptor antagonists have similar efficacy to ACE inhibitors and have fewer side effects, the angiotensin II receptor blockers should be reserved for patients intolerant to ACE inhibitors. In patients requiring diuretic therapy, spironolactone is preferred because of its salutary properties regarding extracellular matrix remodeling, specifically in reducing fibrosis. Surgical revascularization with or without associated mitral valve repair is useful in selected patients with severe ischemic mitral regurgitation or hibernating myocardium. New therapies directed at modulating the remodeling process may focus on manipulating the components of the extracellular matrix to reduce the deleterious impact of this process.

Journal Article↗

PubMed2002

Approaches to statistical analysis of repeated echocardiographic measurements after myocardial infarction and its relation to heart failure: Application of a random-effects model.

BACKGROUND: Extensive left ventricular (LV) dilatation after myocardial infarction (MI) is associated with increased heart failure risk. AIMS: To investigate whether the power to demonstrate the relation between LV dilatation and heart failure depends on the method applied to predict LV dilatation after MI. METHODS: A random-effects model and ANOVA model for repeated measurements (MANOVA) were applied to predict LV volume index during 1 year for 298 post-MI patients. Spearman correlation coefficients (r) were calculated and Cox regression analysis was used to calculate risk ratio's (RR). RESULTS: LV volume indices were more accurately predicted by a random-effects model than by a MANOVA model (systolic/diastolic respectively r = 0.93/0.91 vs. r = 0.67/0.64). Furthermore, patients with high LV volume index as predicted by the random-effects model, had significantly increased heart failure risk (systolic RR 2.04 (95% CI: 1.31 to 3.17; P = 0.001), diastolic RR 1.80 (95% CI: 1.16 to 2.78; P = 0.007). Using the same data, MANOVA failed to demonstrate this relation significantly (systolic RR 1.77 (95% CI: 0.79 to 3.98; P = 0.16), diastolic RR 1.49 (95% CI: 0.68 to 3.30; P = 0.31). CONCLUSION: When analyzing repeated measurement data, random-effect models are more powerful in detecting clinical relations than are MANOVA models, especially in the presence of missing values.

Dilatation, Pathologic↗

PubMed2002

Testing the test: the reliability of echocardiography in the sequential assessment of valvular regurgitation.

BACKGROUND AND OBJECTIVE: Substantial variability in serial echocardiographic qualitative assessment of valvular regurgitation may exist. Reader variability is generally well understood, but acquisition variability (portions of variability caused by equipment, sonographers, physiologic changes) has been less frequently assessed, particularly in combination with reader variability. We attempted to determine the relative contributions of acquisition and reader variability as components of total test-retest variability for aortic (AR) and mitral (MR) regurgitation. METHODS: Outpatient echocardiographic study was done at 2 clinical sites. Twenty-three predominantly obese middle-aged females had 3 echocardiograms, 2 performed 14 +/- 3 days apart and the third performed within 1 to 2 hours of the second. Triplets of echocardiograms were evaluated for change in grade of AR and MR. Medical history, anthropometrics, and blood pressures were obtained. RESULTS: Average intrareader variability (percentage of reads for which there is within-reader disagreement) was 5.6% for AR and 16.7% for MR. The average total test-retest variability (percentage of reads for which there is disagreement between visits) was 29.0% for AR and 24.6% for MR. The acquisition variability for AR was 23.4% +/- 7.7%; for MR, it was 7.9% +/- 10.2%. A significant predictor of change for AR/MR was the initial grade. Change in diastolic blood pressure was positively associated with change in AR and MR. CONCLUSIONS: Intrareader agreement was substantial for AR and MR. Components of total test-retest variability found were reader, biological (change in diastolic blood pressure), and regression to the mean. Recommendations for clinical practice include monitoring blood pressure changes and understanding the confidence limits of the clinical test. Test-retest variability and its components should be considered in echocardiography and other diagnostic testing.

Adolescent↗

PubMed2002

Echocardiographic evaluation of pulmonary artery pressure with clinical correlates in predominantly obese adults.

Pulmonary artery systolic pressure (PASP) was examined in relationship to age, body mass index (BMI), the effects of comorbid disease, and standard echocardiographic measurements of cardiac chamber size, left ventricular filling patterns, and left ventricular systolic function in 5 large cohorts presenting with a primary problem of obesity. For subjects with a measurable PASP, means (+/- SD) across cohorts for age ranged from 46.0 +/- 11.2 to 54.1 +/- 12.8 years, for BMI from 26.0 +/- 4.4 to 37.2 +/- 6.1 kg/m2, and PASP (n = 1515) from 29.9 +/- 7.7 to 33.8 +/- 7.8 mm Hg. PASP 30 mm Hg or greater occurred in 46% to 66% of subjects and 35 mm Hg or greater in 16% to 36%. Age and BMI were the most significant correlates of PASP. Increased PASP was also significantly associated with systemic hypertension and a history of cardiovascular disease. The mean PASP in obese individuals is higher than previously reported with nearly one third having a PASP of 35 mm Hg or greater. Clinical interpretation of PASP should include BMI, age, blood pressure, and presence of cardiovascular disease.

Adult↗

PubMed2002

A comparison of the effects of rosiglitazone and glyburide on cardiovascular function and glycemic control in patients with type 2 diabetes.

OBJECTIVE: This open-label, active-controlled study investigated the cardiac safety and antihyperglycemic effect of rosiglitazone (RSG) in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: Of the 203 patients randomly assigned to RSG (4 mg b.i.d.) or glyburide (GLB) (titrated to achieve optimal glycemic control for the first 8 weeks only to limit the risk of hypoglycemia; mean 10.5 mg/day), 118 had an echocardiogram performed at week 52. Left ventricular (LV) mass index, ejection fraction, and left ventricular end-diastolic volume were assessed by M-mode echocardiography at baseline and weeks 12, 28, and 52; 24-h ambulatory blood pressure was assessed at baseline and at weeks 28 and 52. Glycemic control was assessed by measuring fasting plasma glucose (FPG) and HbA(1c). RESULTS: Neither treatment produced an increase in LV mass index that exceeded 1 SD. Ejection fraction did not change in either group. Both groups had clinically insignificant increases in LV end-diastolic volume. RSG, but not GLB, caused a statistically significant reduction in ambulatory diastolic blood pressure. Both treatments reduced HbA(1c) and FPG. CONCLUSIONS: A total of 52 weeks of therapy with RSG (4 mg b.i.d.) did not adversely affect cardiac structure or function in patients with type 2 diabetes and produced significant and sustained reductions in hyperglycemia. Decreases in ambulatory diastolic blood pressure with RSG were superior to those with GLB.

Adult↗