Randomized trial comparing intravenous nitroglycerin and heparin for treatment of unstable angina secondary to restenosis after coronary artery angioplasty

Heparin versus placebo for non-ST elevation acute coronary syndromes

BACKGROUND

Non-ST elevation acute coronary syndromes (NSTEACS) represent a spectrum of disease including unstable angina and non-ST segment myocardial infarction (NSTEMI). Despite treatment with aspirin, beta-blockers and nitroglycerin, unstable angina/NSTEMI is still associated with significant morbidity and mortality. Although evidence suggests that low molecular weight heparin (LMWH) is more efficacious compared to unfractionated heparin (UFH), there is limited data to support the role of heparins as a drug class in the treatment of NSTEACS. This is an update of a review last published in 2008.

OBJECTIVES

To determine the effect of heparins (UFH and LMWH) compared with placebo for the treatment of patients with non-ST elevation acute coronary syndromes (unstable angina or NSTEMI).

SEARCH METHODS

For this update the Cochrane Heart Group Trials Search Co-ordinator searched the Cochrane Central Register of Controlled Trials on The Cochrane Library (2013, Issue 12), MEDLINE (OVID, 1946 to January week 1 2014), EMBASE (OVID, 1947 to 2014 week 02), CINAHL (1937 to 15 January 2014) and LILACS (1982 to 15 January 2014). We applied no language restrictions.

SELECTION CRITERIA

Randomized controlled trials of parenteral UFH or LMWH versus placebo in people with non-ST elevation acute coronary syndromes (unstable angina or NSTEMI).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed quality of studies and independently extracted data.

MAIN RESULTS

There were no new included studies for this update. Eight studies (3118 participants) were included in this review. We found no evidence for difference in overall mortality between the groups treated with heparin and placebo (risk ratio (RR) = 0.84, 95% confidence interval (CI) 0.36 to 1.98). Heparins compared with placebo, reduced the occurrence of myocardial infarction in patients with unstable angina and NSTEMI (RR = 0.40, 95% CI 0.25 to 0.63, number needed to benefit (NNTB) = 33). There was a trend towards more major bleeds in the heparin studies compared to control studies (RR = 2.05, 95% CI 0.91 to 4.60). From a limited data set, there appeared to be no difference between patients treated with heparins compared to control in the occurrence of thrombocytopenia (RR = 0.20, 95% CI 0.01 to 4.24). Assessment of overall risk of bias in these studies was limited as most of the studies did not give sufficient detail to allow assessment of potential risk of bias.

AUTHORS' CONCLUSIONS

Compared with placebo, patients treated with heparins had a similar risk of mortality, revascularization, recurrent angina, and thrombocytopenia. However, those treated with heparins had a decreased risk of myocardial infarction and a higher incidence of minor bleeding. Overall, the evidence assessed in this review was classified as low quality according to the GRADE approach. The results presented in this review must therefore be interpreted with caution.

Heparin versus placebo for acute coronary syndromes

BACKGROUND

Acute coronary syndromes (ACS) represent a spectrum of disease including unstable angina (UA) and non-ST segment myocardial infarction (NSTEMI). Despite treatment with aspirin, beta-blockers and nitroglycerin, UA/NSTEMI is still associated with significant morbidity and mortality. Although emerging evidence suggests that low molecular weight heparin (LMWH) is more efficacious compared to unfractionated heparin (UFH), there is limited data to support the role of heparins as a drug class in the treatment of ACS.

OBJECTIVES

To determine the effect of heparins (UFH and LMWH) compared with placebo for the treatment of patients with ACS.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials on The Cochrane Library (issue 4, 2002), MEDLINE (1966 to May 2002), EMBASE (1980 to May 2002) and CINAHL (1982 to May 2002). Authors of included studies and pharmaceutical industry representatives were contacted to determine if unpublished studies which met the inclusion criteria were available.

SELECTION CRITERIA

Randomized controlled trials of parenteral UFH or LMWH versus placebo in people with ACS (UA or NSTEMI).

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed quality of studies. Data were extracted independently by two reviewers. Study authors were contacted to verify and clarify missing data.

MAIN RESULTS

Eight studies (3118 participants) were included in this review. We found no evidence for difference in overall mortality between the groups treated with heparin and placebo (RR = 0.84, 95% CI 0.36 to 1.98). Heparins reduced the occurrence of MI (RR = 0.40, 95% CI 0.25 to 0.63, NNT = 33). An increase in the incidence of minor bleeds (RR = 6.80, 95% CI 1.23 to 37.49, NNH = 17).

AUTHORS' CONCLUSIONS

Compared to placebo, patients treated with heparins had similar risk of mortality, revascularization, recurrent angina, major bleeding and thrombocytopenia. However, those treated with heparins had decreased risk of MI and a higher incidence of minor bleeding.

Side effects of using nitrates to treat heart failure and the acute coronary syndromes, unstable angina and acute myocardial infarction

Nitrates are potent venous dilators and anti-ischemic agents. They are widely used for the relief of chest pain and pulmonary congestion in patients with acute coronary syndromes and heart failure. Nitrates, however, do not reduce mortality in patients with acute coronary syndromes. Combination of nitrates and hydralazine when given in addition to beta-blockers and angiotensin-converting enzyme (ACE) inhibitors reduce mortality and heart failure hospitalizations in patients with heart failure due to left ventricular systolic dysfunction who are of African-American origin. Side effects during nitrate therapy are common but are less well described in the literature compared with the reported side effects in patients with stable angina pectoris. The reported incidence of side effects varies highly among different studies and among various disease states. Headache is the most commonly reported side effect with an incidence of 12% in acute heart failure, 41-73% in chronic heart failure, 3-19% in unstable angina and 2-26% in acute myocardial infarction. The reported incidence of hypotension also differs: 5-10% in acute heart failure, 20% in chronic heart failure, 9% in unstable angina and < 1-48% in acute myocardial infarction, with the incidence being much higher with concomitant nitrate therapy plus angiotensin-converting enzyme inhibitors. Reported incidence of dizziness is as low as 1% in patients with acute myocardial infarction to as high as 29% in patients with heart failure. Severe headaches and/or symptomatic hypotension may necessitate discontinuation of nitrate therapy. Severe life threatening hypotension or even death may occur when nitrates are used in patients with acute inferior myocardial infarction associated with right ventricular dysfunction or infarction, or with concomitant use of phosphodiesterase-5 inhibitors or N-acetylcysteine. Despite the disturbing observational reports in the literature that continuous and prolonged use of nitrates may lead to increased mortality and recurrent myocardial infarction in patients with stable coronary artery disease, no such adverse effects of nitrates have been reported in the large randomized trials in patients with acute myocardial infarction or chronic heart failure.

Effects of heparin on the production of homocysteine-induced extracellular matrix metalloproteinase-2 in cultured rat vascular smooth muscle cells

OBJECTIVE

To study the effects of heparin on the production of homocysteine-induced extracellular matrix metalloproteinase-2 (MMP-2) in cultured rat vascular smooth muscle cells.

METHODS

The effects of different homocysteine levels (0 micromol/L to 1000 micromol/L) on MMP-2 production and the effects of different heparin concentrations (0 microg/mL to 100 microg/mL) on homocysteine-induced MMP-2 in cultured rat vascular smooth muscle cells were examined using gelatin zymography and Western blotting. The changes in MMP-2 were further compared with various treatments for 24 h, 48 h and 72 h.

RESULTS

Homocysteine (50 micromol/L to 1000 micromol/L) increased the production of MMP-2 significantly in a dose-dependent manner. Increased production of MMP-2 induced by homocysteine was reduced by the extracellular addition of heparin in a dose-dependent manner. Production of MMP-2 with various treatment regimens for 72 h was greater than for 24 h and 48 h.

CONCLUSIONS

Extracellular addition of heparin decreased homocysteine-induced MMP-2 secretion. Data suggest a mechanism by which hyperhomocysteinemia is involved in the pathogenesis of coronary artery disease and demonstrate a beneficial effect of heparin on these conditions.

A meta-analysis of clinical trials of paclitaxel- and sirolimus-eluting stents in patients with obstructive coronary artery disease

AIM

This meta-analysis was conducted to compare the effects of drug (paclitaxel and sirolimus)-eluting stents with bare metal stents on major adverse cardiac events, restenosis rates and late loss of arterial lumen diameter in patients with obstructive coronary artery disease.

METHODS

Randomized, controlled clinical trials comparing sirolimus- and paclitaxel-eluting stents with bare metal stents were identified through electronic and manual search. Fixed effects method of Mantel-Haenszel and random effects method of DerSimonian and Laird were used for computing the pooled odds ratio (OR) and 95% confidence intervals (CI) for major adverse cardiac events and restenosis rates. Standardized mean difference with 95% CI was calculated for late-loss of arterial lumen diameter.

RESULTS

A total of 13 studies were included in the meta-analysis. As compared with bare metal stents, the use of sirolimus- and paclitaxel-eluting stents significantly reduced the major adverse cardiac events (pooled OR 0.35; 95% CI 0.24-0.50), restenosis rates (pooled OR 0.27; 95% CI 0.15-0.47), and late loss of arterial lumen diameter (mean difference 0.57 mm, 95% CI 0.49-0.68).

CONCLUSION

Paclitaxel- and sirolimus-eluting stents significantly reduced the incidence of major adverse cardiac events, restenosis rates, and late loss of arterial lumen diameter as compared with bare metal stents.

[Gene therapy of restenosis and atherosclerosis: hopes and facts]

Stents are the main technique of coronary revascularization in France and western countries. However, a better understanding of the pathophysiology of in-stent restenosis and the well-recognized roles played by inflammation and cell proliferation led to the development of drug-eluting stents, which have nearly eliminated the risk of restenosis. In this context, the success of gene therapy will depend on our ability to simplify and optimize current protocols of arterial gene transfer. For the time being, arterial gene therapy remains a powerful tool for deciphering the complex pathophysiology of restenosis and will certainly have far-reaching implications in the fields of vascular biology and therapeutics.

Comprehensive management of hypertensive emergencies and urgencies

Despite advances in chronic hypertension management, hypertensive emergencies and urgencies remain as serious complications. Much of this relates to poor compliance with effective antihypertensive management. Hypertensive emergencies and urgencies can also be seen as the initial manifestations of hypertension in pregnancy and in the perioperative period. Multiple classes of intravenous antihypertensive drugs are available to treat hypertensive emergencies, and specific agents may have an advantage in a given clinical situation. Orally active agents are used to treat hypertensive urgencies, and include clonidine, angiotensin-converting enzyme inhibitors, and labetalol. Most patients respond to drug therapy, but problems may arise related to a rapid normalization of blood pressure.

Coronary artery endothelial protection after local delivery of 17beta-estradiol during balloon angioplasty in a porcine model: a potential new pharmacologic approach to improve endothelial function

OBJECTIVES

The goal of this research was to study the effect of locally delivered 17beta-estradiol (17beta-E) during angioplasty on endothelial function after percutaneous transluminal coronary angioplasty (PTCA) at four weeks.

BACKGROUND

The endothelium plays a major role in the structural and functional integrity of coronary arteries and is damaged by PTCA.

METHODS

Juvenile swine were subjected to PTCA, after which each artery was randomly-assigned to 600-microg 17beta-E delivered locally, an equal volume of vehicle (V) or PTCA alone. After four weeks, the improvement in endothelial function was assessed by angiography using intracoronary acetylcholine (Ach) infusion and by immunohistochemistry.

RESULTS

At 10(-5) mol/l and 10(-4) mol/l Ach, significant vasoconstriction was noted in arteries treated with PTCA alone (p < 0.01 and p < 0.0001, respectively) and with PTCA plus V (p < 0.02 and p < 0.001, respectively). No significant vasoconstrictive response to Ach was observed in arteries treated with PTCA plus 17beta-E. Immunohistochemistry of vessels four weeks after PTCA revealed enhanced re-endothelialization (p < 0.0005) and endothelial nitric-oxide synthase (eNOS) expression (p < 0.0005) in PTCA plus 17beta-E-treated arteries compared with the other two treatment groups. Arteries treated with 17beta-E showed significantly lower neointima formation, which correlated inversely with the extent of re-endothelialization and eNOS expression.

CONCLUSIONS

Locally delivered 17beta-E significantly enhances re-endothelialization and endothelial function after PTCA, possibly by improving the expression of eNOS. Since endothelial dysfunction can promote both restenosis and coronary spasm, local 17beta-E administration is a promising new approach to improve long-term results after PTCA.