Availability of on-site catheterization and clinical outcomes in patients receiving fibrinolysis for ST-elevation myocardial infarction

AIMS

To compare management and clinical outcomes in hospitals stratified by the availability of on-site catheterization in InTIME-II, a multicentre trial comparing alteplase with lanoteplase for acute myocardial infarction.

METHODS AND RESULTS

We studied 15,078 patients enrolled in 35 countries and 855 hospitals. Thirty-one percent of hospitals had 24-h, 25% day-only, and 44% no on-site catheterization facilities. Rates of cardiac angiography (57%, 38%, 26%) and revascularization (37%, 21%, 17%) were higher in hospitals with increasing access to on-site facilities(P<0.0001). The presence of a 24-h on-site facility was the strongest predictor of angiography during the index admission (odds ratio 4.17, 95% CI 3.85-4.54). There were no major differences in patient outcomes at 30 days when hospitals were stratified by availability of on-site catheterization. Adjusted 1-year mortality was similar between groups of hospitals (odds ratio for day-only 0.94 [0.80-1.09] and odds ratio for no availability 0.95 [0.83-1.10] compared to hospitals with 24-h facilities).

CONCLUSIONS

There is a marked variation in procedure use by the availability of on-site catheterization with no major differences in patient outcomes. There is a need for additional randomized trials in the current era to address both the appropriate selection of patients and timing of invasive procedures in ST-elevation acute myocardial infarction.

Geographic variation in patient and hospital characteristics, management, and clinical outcomes in ST-elevation myocardial infarction treated with fibrinolysis. Results from InTIME-II

AIMS

We examined the geographic variations in InTIME-II, a randomized double-blind trial comparing alteplase with lanoteplase for myocardial infarction.

METHODS AND RESULTS

We compared baseline characteristics, management, and outcomes in four regions (Western Europe, Eastern Europe, North America, and Latin America) and in countries with historically different management approaches (Germany vs the U.K., the U.S. vs Canada). Thirty-day mortality in Western Europe, Eastern Europe, North America and Latin America was 6.7%, 7.3%, 5.7%, 10.1%, P<0.0001. Adjusted mortality for Europe was intermediate between North America and Latin America (odds ratios (OR) [95% confidence intervals (CI)] compared to Western Europe: North America 0.84 [0.67-1.0], Eastern Europe 1.2 [1.0-1.4], and Latin America 1.8 [1.3-2.7]). Revascularization rates varied 10-fold but did not explain regional mortality differences. Germany and the U.K. had similar adjusted 1-year mortality (OR for the U.K. 1.16 [0.92-1.5]), although invasive procedures were four- to 10-fold more common in Germany. Similarly the U.S. and Canada had equal adjusted 1-year mortality (OR for Canada 0.85 [0.61-1.17]) despite three-fold higher use of invasive procedures in the U.S.

CONCLUSIONS

Significant geographic variations in practice and adjusted mortality following fibrinolysis persist despite recent guidelines. These findings have important implications in the design and interpretation of international studies, identify under- and over-utilized therapies, and support further study of treatments with marked worldwide variations.

HMG-CoA reductase inhibitor mobilizes bone marrow--derived endothelial progenitor cells

Endothelial progenitor cells (EPCs) have been isolated from circulating mononuclear cells in peripheral blood and shown to incorporate into foci of neovascularization, consistent with postnatal vasculogenesis. These circulating EPCs are derived from bone marrow and are mobilized endogenously in response to tissue ischemia or exogenously by cytokine stimulation. We show here, using a chemotaxis assay of bone marrow mononuclear cells in vitro and EPC culture assay of peripheral blood from simvastatin-treated animals in vivo, that the HMG-CoA reductase inhibitor, simvastatin, augments the circulating population of EPCs. Direct evidence that this increased pool of circulating EPCs originates from bone marrow and may enhance neovascularization was demonstrated in simvastatin-treated mice transplanted with bone marrow from transgenic donors expressing beta-galactosidase transcriptionally regulated by the endothelial cell-specific Tie-2 promoter. The role of Akt signaling in mediating effects of statin on EPCs is suggested by the observation that simvastatin rapidly activates Akt protein kinase in EPCs, enhancing proliferative and migratory activities and cell survival. Furthermore, dominant negative Akt overexpression leads to functional blocking of EPC bioactivity. These findings establish that augmented mobilization of bone marrow-derived EPCs through stimulation of the Akt signaling pathway constitutes a novel function for HMG-CoA reductase inhibitors.

HMG-CoA reductase inhibitor mobilizes bone marrow--derived endothelial progenitor cells

Endothelial progenitor cells (EPCs) have been isolated from circulating mononuclear cells in peripheral blood and shown to incorporate into foci of neovascularization, consistent with postnatal vasculogenesis. These circulating EPCs are derived from bone marrow and are mobilized endogenously in response to tissue ischemia or exogenously by cytokine stimulation. We show here, using a chemotaxis assay of bone marrow mononuclear cells in vitro and EPC culture assay of peripheral blood from simvastatin-treated animals in vivo, that the HMG-CoA reductase inhibitor, simvastatin, augments the circulating population of EPCs. Direct evidence that this increased pool of circulating EPCs originates from bone marrow and may enhance neovascularization was demonstrated in simvastatin-treated mice transplanted with bone marrow from transgenic donors expressing beta-galactosidase transcriptionally regulated by the endothelial cell-specific Tie-2 promoter. The role of Akt signaling in mediating effects of statin on EPCs is suggested by the observation that simvastatin rapidly activates Akt protein kinase in EPCs, enhancing proliferative and migratory activities and cell survival. Furthermore, dominant negative Akt overexpression leads to functional blocking of EPC bioactivity. These findings establish that augmented mobilization of bone marrow-derived EPCs through stimulation of the Akt signaling pathway constitutes a novel function for HMG-CoA reductase inhibitors.

HMG-CoA reductase inhibitor mobilizes bone marrow--derived endothelial progenitor cells

Endothelial progenitor cells (EPCs) have been isolated from circulating mononuclear cells in peripheral blood and shown to incorporate into foci of neovascularization, consistent with postnatal vasculogenesis. These circulating EPCs are derived from bone marrow and are mobilized endogenously in response to tissue ischemia or exogenously by cytokine stimulation. We show here, using a chemotaxis assay of bone marrow mononuclear cells in vitro and EPC culture assay of peripheral blood from simvastatin-treated animals in vivo, that the HMG-CoA reductase inhibitor, simvastatin, augments the circulating population of EPCs. Direct evidence that this increased pool of circulating EPCs originates from bone marrow and may enhance neovascularization was demonstrated in simvastatin-treated mice transplanted with bone marrow from transgenic donors expressing beta-galactosidase transcriptionally regulated by the endothelial cell-specific Tie-2 promoter. The role of Akt signaling in mediating effects of statin on EPCs is suggested by the observation that simvastatin rapidly activates Akt protein kinase in EPCs, enhancing proliferative and migratory activities and cell survival. Furthermore, dominant negative Akt overexpression leads to functional blocking of EPC bioactivity. These findings establish that augmented mobilization of bone marrow-derived EPCs through stimulation of the Akt signaling pathway constitutes a novel function for HMG-CoA reductase inhibitors.

Bolus fibrinolytic therapy in acute myocardial infarction

CONTEXT

New bolus fibrinolytics derived from the human tissue-type plasminogen activator (tPA) have emerged as a means of dissolution of occlusive thrombosis associated with acute myocardial infarction.

OBJECTIVE

To review the new bolus fibrinolytic drugs derived from tPA: reteplase, lanoteplase, and tenecteplase.

DATA SOURCES

The MEDLINE, EMBASE, and Current Contents databases were searched for articles from 1983 to 2001, using the index terms pharmacokinetics, pharmacodynamics, plasminogen activator, reteplase, lanoteplase, and tenecteplase. Additional data sources included bibliographies of articles identified on MEDLINE, EMBASE, and Current Content, inquiry of experts and pharmaceutical companies, and preliminary data presented at recent national and international cardiology conferences.

STUDY SELECTION

We selected for review studies that evaluated the pharmacokinetics and pharmacodynamics of reteplase, lanoteplase, and tenecteplase, and assessed the effects of these bolus fibrinolytic drugs on the angiographic and immediate and long-term outcomes of patients. Of 138 articles identified, 38 were analyzed.

DATA EXTRACTION

Data quality was determined by publication in the peer-reviewed literature or presentation at an official cardiology society-sponsored meeting.

DATA SYNTHESIS

Tenecteplase and reteplase are comparable with accelerated infusion recombinant tPA in terms of efficacy and safety but more convenient because they are administered by bolus injection. Lanoteplase and heparin bolus plus infusion is as effective as tPA with regard to mortality, but the rate of intracranial hemorrhage is significantly higher.

CONCLUSION

Given the ease of administration and the similar outcomes compared with accelerated infusion recombinant tPA, it is likely that a key component of contemporary reperfusion will include a bolus fibrinolytic.

Effects of growth hormone (GH) administration on homocyst(e)ine levels in men with GH deficiency: a randomized controlled trial

GH deficiency is associated with increased cardiovascular mortality and early manifestations of atherosclerosis. Elevated serum homocyst(e)ine levels have been found to be associated with increased cardiovascular risk. The effect of GH replacement on homocyst(e)ine has not been investigated to date. We evaluated the effect of GH replacement on fasting homocyst(e)inemia in a group of men with adult-onset GH deficiency in a randomized, single blind, placebo-controlled trial. Forty men with adult-onset GH deficiency were randomized to GH or placebo for 18 months, with dose adjustments made according to serum insulin-like growth factor I (IGF-I) levels. Fasting serum homocyst(e)ine, folate, vitamin B12, and total T(3) levels were determined at baseline and 6 and 18 months. Anthropometry, IGF-I levels, insulin, and glucose were measured at 1, 3, 6, 12, and 18 months. Nutritional assessment, body composition, total T(4), thyroid hormone binding index, and free T(4) index were assessed every 6 months. Homocyst(e)ine decreased in the GH-treated group compared with that in the placebo group (net difference, -1.2 +/- 0.6 micromol/L; confidence interval, -2.4, -0.02 micromol/L; P = 0.047). Homocyst(e)ine at baseline was negatively correlated with plasma levels of folate (r = -0.41; P = 0.0087). Total T(3) increased in the GH-treated group vs. that in the placebo group (net difference, 0.17 +/- 0.046 ng/dL; confidence interval, 0.071, 0.26 nmol/L; P = 0.0012). Folate and vitamin B12 levels did not significantly change between groups. Changes in homocyst(e)ine were negatively correlated with changes in IGF-I. For each 1 nmol/L increase in IGF-I, homocyst(e)ine decreased by 0.04 +/- 0.02 micromol/L (P = 0.029). In contrast, changes in homocyst(e)ine did not correlate with changes in folate, vitamin B12, total T(3), C-reactive protein, interleukin-6, or insulin levels. This study shows that GH replacement decreases fasting homocyst(e)ine levels compared with placebo. This may be one of the mechanisms involved in the putative modulation of atherosclerosis and cardiovascular risk by GH replacement.

Prognostic assessment of uncomplicated first myocardial infarction by exercise echocardiography and Tc-99m tetrofosmin gated SPECT

BACKGROUND

We evaluate the prognostic value of stress echo and gated single photon emission computed tomography (SPECT) after a first uncomplicated acute myocardial infarction.

METHODS AND RESULTS

We used predischarge maximal subjective exercise echocardiography and gated SPECT with technetium 99m tetrofosmin to prospectively study 103 patients younger than 70 years with a first acute myocardial infarction. During a 12-month follow-up period, 2 patients died, 9 had heart failure, and 29 had ischemic complications (4 reinfarction and 25 angina). Predictive variables for heart failure in multivariate analysis were ejection fraction evaluated by echocardiography (odds ratio [OR] 8.5, P =.016) or by gated SPECT (OR 10.7, P =.009). Predictive variables for ischemic complications in multivariate analysis were less than 5 metabolic equivalents (METS) in exercise test (OR 5.2, P =.007) and greater than 15% ischemic extent in the polar map (OR 3.6, P =.04) of SPECT.

CONCLUSIONS

Exercise echocardiography and Tc-99m tetrofosmin gated SPECT were predictive for heart failure, but exercise SPECT was the only test with predictive power for ischemic complications.

Pharmacology and clinical trial results of lanoteplase in acute myocardial infarction

New bolus fibrinolytic agents derived from the recombinant human tissue plasminogen activator (t-PA) have emerged as a new means of dissolution of the occlusive thrombosis associated with acute myocardial infarction. Lanoteplase is a fibrinolytic drug derived from t-PA by deleting its fibronectin finger-like and epidermal growth factor domains and mutating Asn(117) to Gln(117). Lanoteplase has a reduced plasma clearance and a prolonged half-life such that it can be administered as a single bolus. In the InTIME I trial, patency (TIMI grade 2 or 3 flow) with the 120 KU/kg dose was higher compared with front-loaded t-PA. The InTIME II trial demonstrated that lanoteplase was as effective as alteplase with regard to mortality. However, the rate of intracranial haemorrhage was significantly higher in lanoteplase-treated patients and further development of this compound has been halted.

Heart-type fatty acid binding protein as a marker of reperfusion after thrombolytic therapy

Accurate, rapid, and simple noninvasive measures of infarct-related artery (IRA) patency are needed to identify patients with failed coronary reperfusion for rescue percutaneous coronary intervention (PCI). Heart-type Fatty Acid Binding Protein (H-FABP) is a small, cytosolic protein found in high concentrations in the myocardium. We evaluated the efficacy of H-FABP as a marker for successful reperfusion after thrombolysis. Fifty-eight subjects from the TIMI 14 trial had H-FABP and myoglobin concentrations measured at baseline (immediately prior to thrombolysis) and 60, 90, and 180 min after thrombolysis. All patients underwent coronary angiography at 90 min. By 60 min after thrombolysis, median concentrations of H-FABP and myoglobin were significantly higher in patients with a patent IRA than in those with an occluded IRA (P<0.01 for each). Similarly, the 60 and 90 min/baseline H-FABP and myoglobin ratios were significantly higher among patients with a patent IRA (P<0.01 for each). There were no significant differences in marker concentrations or ratios between patients with TIMI grade 2 and TIMI grade 3 flow. The area under the ROC curve tended to be greater for the 60 and 90 min/baseline myoglobin ratios than for similar ratios of H-FABP (0.71 and 0.73 vs. 0.64 and 0.62; P=ns). In conclusion, successful reperfusion can be detected within the first 60 min after thrombolysis with either H-FABP or myoglobin. Despite a favorable kinetic profile, however, H-FABP does not appear to represent a significant advance over myoglobin in the noninvasive detection of reperfusion after thrombolysis.

Effects of growth hormone administration on inflammatory and other cardiovascular risk markers in men with growth hormone deficiency. A randomized, controlled clinical trial

BACKGROUND

Growth hormone-deficient adults have increased cardiovascular mortality. Growth hormone replacement may affect cardiovascular risk. Inflammation plays an important role in atherosclerosis, and inflammatory markers are predictive of cardiovascular events.

OBJECTIVE

To investigate the effect of growth hormone replacement on inflammatory and other cardiovascular risk factors.

DESIGN

Randomized, single-blind, placebo-controlled trial.

PATIENTS

40 men with adult-onset growth hormone deficiency.

INTERVENTION

Growth hormone or placebo given for 18 months at a dose adjusted for normal serum insulin-like growth factor I level.

MEASUREMENTS

Anthropometric, hemoglobin A1c, and central fat values were assessed every 6 months. Levels of glucose, insulin, insulin-like growth factor I, and lipids were measured at 1, 3, 6, 12, and 18 months. C-reactive protein, serum amyloid polypeptide A, inteleukin-6, and lipoprotein(a) levels were determined at baseline and 6 and 18 months.

RESULTS

C-reactive protein and inteleukin-6 levels decreased in growth hormone recipients compared with placebo recipients (differences between groups, -1.9 +/- 0.6 mg/L [P = 0.0027] and -1.3 +/- 0.5 ng/L [P = 0.013], respectively). Changes in serum amyloid polypeptide A levels between groups did not reach statistical significance (difference between groups, -2.4 +/- 1.2 mg/L; P = 0.056). Serum cholesterol levels, low-density lipoprotein cholesterol levels, and ratios of total cholesterol to high-density lipoprotein cholesterol decreased in growth hormone recipients in the first 3 months compared with placebo recipients (differences between groups, -0.86 +/- 0.17 mmol/L [-33.2 +/- 6.6 mg/dL] [P < 0.001], -0.63 +/- 0.20 mmol/L [-24.5 +/- 5.9 mg/dL] [P < 0.001], and -0.56 +/- 0.26 [P = 0.040], respectively), but the decrease was not maintained from month 6 to month 18. Lipoprotein(a) levels increased (difference between groups, 22.0 +/- 8.0 mg/L; P = 0.0096). Short-term increases occurred in glucose levels, insulin levels, and insulin-to-glucose ratios (differences between groups, 0.54 +/- 0.16 mmol/L [9.6 +/- 2.8 mg/dL] [P = 0.0018], 37.9 +/- 9.6 pmol/L [P < 0.001], and 6.0 +/- 1.8 [P = 0.0025], respectively), but only the increase in glucose level was maintained over the long term (difference between groups, 0.56 +/- 0.17 mmol/L [10.0 +/- 3.1 mg/dL]; P = 0.0026). Hemoglobin A1c values did not change. Truncal fat-to-total fat ratios decreased (difference between groups, -0.018 +/- 0.007; P = 0.0087).

CONCLUSIONS

Long-term growth hormone replacement in men reduces levels of inflammatory cardiovascular risk markers, decreases central fat, and increases lipoprotein(a) and glucose levels without affecting lipid levels.

Degree of residual stenosis in the culprit coronary artery after thrombolytic administration (Thrombolysis In Myocardial Infarction [TIMI] trials)

This study was undertaken to characterize residual stenosis after thrombolytic administration and to evaluate clinical and angiographic features and early outcomes of patients with mild residual obstruction after thrombolytic administration. Patients who underwent angiography at 90 minutes after thrombolytic administration in the Thrombolysis In Myocardial Infarction 4, 10A, 10B, and 14 trials were divided into 3 groups according to the degree of residual stenosis measured by quantitative coronary angiography: patients with a patent culprit artery with <50% stenosis, patients with patent arteries and residual stenosis > or =50%, and patients with occluded arteries. Only 8.9% of the patients (188 of 2,119) had an infarct-related artery luminal diameter stenosis of <50% 90 minutes after thrombolysis. Compared with patients with patent arteries and > or =50% stenosis, patients with mild residual obstruction were younger (56.8 vs 58.6 years; p = 0.03), had fewer prior myocardial infarctions (6.9% vs 13.3%; p = 0.01), fewer eccentric (19.8% vs 42.1%; p <0.0001), ulcerated (7.5% vs 13.2%; p = 0.03), and collateralized (6.6% vs 13.2%, p = 0.01) lesions, but a greater thrombus burden (29.7% vs 18.3%, p = 0.0002). Among patients with patent arteries, a residual stenosis of <50% was associated with a significantly lower composite of in-hospital death, myocardial infarction, and congestive heart failure (2.8% vs 7.1%, p = 0.03). Thus, a minority of patients have a mild residual obstruction at 90 minutes after thrombolytic administration. These patients have less complex lesions with greater thrombus burdens and better clinical outcomes.

A practical approach to the diagnosis and management of thrombocytopenia associated with glycoprotein IIb/IIIa receptor inhibitors

The introduction of drugs that inhibit the GP IIb/IIIa receptor represents one of the most important new developments in the field of cardiovascular pharmacotherapeutics of the past decade. Thrombocytopenia associated with a GP IIb/IIIa inhibitor can occur in up to 5% of patients and is associated with poor clinical outcomes. Monitoring of the platelet count early after administration of these drugs is recommended and further assessment of the platelet count should be performed with long-term oral administration. Confirmation of true thrombocytopenia and an investigation of other potential etiologies are crucial initial diagnostic steps that should be taken when a platelet count of <100, 000/cm(3) is encountered. In patients receiving concomitant heparin, identification of heparin-induced thrombocytopenia using an enzyme-linked immunosorbent assay to detect anti-heparin-PF4 antibodies is preferred. Treatment recommendations depend upon the severity of thrombocytopenia and presence of bleeding. In general, GP IIb/IIIa inhibitor therapy should be stopped; conventional critical care instituted; and platelet transfusions considered if the platelet count is <10,000/cm(3), if there is severe bleeding, or if an emergency invasive procedure is required. Readministration of GP IIb/IIIa inhibitors may be associated with an increased risk of thrombocytopenia in selected circumstances, and caution is advised if the patient had previously experienced a significant decline in the platelet count or developed drug-induced antibodies following prior use. Future areas of research should target the mechanism(s) of thrombocytopenia, more accurate diagnostic methods, and the risk of thrombocytopenia when these drugs are combined with other antiplatelet and anticoagulant agents.

L-arginine limits myocardial cell death secondary to hypoxia-reoxygenation by a cGMP-dependent mechanism

The objective of this study was to investigate the effect of L-arginine supplementation on myocardial cell death secondary to hypoxia-reoxygenation. Isolated rat hearts (n = 51) subjected to 40 min of hypoxia and 90 min of reoxygenation received 3 mM L-arginine and/or 1 microM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; a selective inhibitor of soluble guanylyl cyclase) throughout the experiment or during the equilibration, hypoxia, or reoxygenation periods. The incorporation of L-[3H]arginine into myocytes during energy deprivation was investigated in isolated adult rat myocytes. The addition of L-arginine to the perfusate throughout the experiment resulted in higher cGMP release (P < 0.05), reduced lactate dehydrogenase release (P < 0.05), and increased pressure-rate product (P < 0.05) during reoxygenation. These effects were reproduced when L-arginine was added only during equilibration, but addition of L-arginine during hypoxia or reoxygenation had no effect. Addition of ODQ either throughout the experiment or only during reoxygenation reversed the beneficial effects of L-arginine. L-[3H]arginine was not significantly incorporated into isolated myocytes subjected to energy deprivation. We conclude that L-arginine supplementation protects the myocardium against reoxygenation injury by cGMP-mediated actions. To be effective during reoxygenation, L-arginine must be added before anoxia.