Comparison of the effect of pressure loading on left ventricular size, systolic and diastolic function in canines with left ventricular dysfunction with preserved and reduced ejection fraction.

BACKGROUND: Decompensated heart failure may present with severe hypertension in patients with preserved (PreEF) or reduced left ventricular (LV) ejection fraction (RedEF) and is clinically indistinguishable. Previously, we demonstrated that arterial pressure elevation increases LV filling pressures in a canine model of chronic LV dysfunction with PreEF or RedEF. It is not clear whether any differences in hemodynamics, LV volume or performance, or diastolic function can be demonstrated between canines with PreEF or RedEF in response to arterial pressure elevation. We hypothesized that the LV systolic, diastolic, and hemodynamic response to pressure loading would be similar in RedEF or PreEF. METHODS: We studied 25 dogs with chronic LV dysfunction due to coronary microsphere embolization with RedEF (35 +/- 4%) and 20 dogs with PreEF (50 +/- 3%). Arterial pressure was increased with methoxamine infusion and hemodynamics and echo-Doppler parameters of LV size, function, transaortic and transmitral pulsed Doppler prior to and with methoxamine infusion was obtained. RESULTS: Though LV filling pressures were similar at baseline, LV size was larger (p < 0.01) and ejection fraction lower in dogs with RedEF (p < 0.001). With methoxamine, there were similar increases in LV size, LV pressures, and index of myocardial performance with the ejection fraction reduced similarly. Diastolic parameters demonstrated similar tau increases, E/A reduction, and diastolic filling shortening in RedEF and PreEF dogs. A similar extent of isovolumic contraction and relaxation times and index of myocardial performance prolongation occurred with pressure loading. CONCLUSION: Pressure loading in a canine model of LV dysfunction with PreEF and RedEF resulted in similar degrees of LV dilatation, increased filling pressures, and increased index of myocardial performance.

Prognostic significance of troponin T elevation in patients without chest pain.

Increased cardiac troponin with chest pain is important for the diagnosis, triage, and treatment of patients in the emergency department. However, the use of troponin for the diagnosis and triage of patients without chest pain is poorly established. The aim of this study was to determine 30-day and 1-year mortality and morbidity of troponin T increases in patients without chest pain. This retrospective study compared 92 hospitalized patients without (study group) and 91 patients with chest pain (control group), followed up for 1 year. Study group patients had troponin T >0.04 microg/L, normal creatine kinase or creatine kinase-MB fraction <5%, and no electrocardiographic ischemia. Excluded were high-risk patients with end-stage kidney disease, those with left ventricular ejection fraction <40%, and the critically ill. Outcome variables included 30-day and 1-year death, myocardial infarction, unstable angina, and coronary revascularization rates. Thirty-day (13.0% vs 4.4%; p = 0.032) and 1-year (33% vs 4.6%; p <0.001) mortality rates were significantly higher in the study group, whereas myocardial infarction, unstable angina, and revascularization were infrequent. In conclusion, patients with increased troponin T and no chest pain had a high mortality rate and required careful follow-up.

Selecting patients with mitral regurgitation and left ventricular dysfunction for isolated mitral valve surgery.

BACKGROUND: American College of Cardiology/American Heart Association (ACC/AHA) Guidelines state that patients with an ejection fraction (EF) of 30% or less should not undergo mitral valve replacement for mitral regurgitation (MR). We sought to establish, using a national cardiac surgery database, whether patients with left ventricular dysfunction may safely undergo mitral valve surgery for MR, and if so, which ones. METHODS: We queried the Society of Thoracic Surgeons (STS) National Database to identify patients who had isolated mitral valve replacement or repair for MR between 1998 and 2001. Mortality and morbidity outcomes were compared by EF category (< or = 30% vs > 30%), and observed mortality compared by EF group, stratified by predicted risk for mortality. A classification and regression tree (CART) model was then used to determine which patient characteristics contributed most to designate the high-risk patient. RESULTS: Of the 14,582 patients who had mitral valve surgery, 727 had an EF of 30% or less and 13,855 had an EF of more than 30%. Observed mortality rates were higher for patients with an EF of 30% or less (5.4% vs 3.1%). However, for low-risk to medium-risk patients, mortality rates remained fairly constant across levels of EF. Mortality is notably increased in the high-risk patients (predicted risk > 10%). A classification tree identifies three key characteristics for high risk: age more than 75 years, renal failure, and emergent or salvage procedure. CONCLUSIONS: When the predicted mortality risk is less than 10%, EF has minimal impact on operative mortality for mitral regurgitation. In contrast to the ACC/AHA Guidelines, our data show that operative risk for mitral valve surgery is not prohibitive for most patients with ventricular dysfunction.