Pharmacologic Therapy for Reducing Myocardial Infarct Size in Clinical Trials

In patients with acute ST-segment elevation myocardial infarction, early, successful, and durable reperfusion therapy optimizes the likelihood of favorable outcomes. Fibrinolysis and primary percutaneous coronary intervention improve survival compared to no reperfusion therapy in large part by reducing infarct size (IS) and preserving left ventricular ejection fraction. There is direct correlation between IS and clinical outcomes. In this article, we will review some of the more promising pharmacological agents geared toward reduction in IS, discuss the major pathways that can lead to this desirable outcome, and evaluate the results of clinical trials performed with these and other compounds.

Targeting reperfusion injury in acute myocardial infarction: a review of reperfusion injury pharmacotherapy

INTRODUCTION

Acute myocardial infarction (AMI) (secondary to lethal ischemia-reperfusion [IR]) contributes to much of the mortality and morbidity from ischemic heart disease. Currently, the treatment for AMI is early reperfusion; however, this itself contributes to the final myocardial infarct size, in the form of what has been termed 'lethal reperfusion injury'. Over the last few decades, the discovery of the phenomena of ischemic preconditioning and postconditioning, as well as remote preconditioning and remote postconditioning, along with significant advances in our understanding of the cardioprotective pathways underlying these phenomena, have provided the possibility of successful mechanical and pharmacological interventions against reperfusion injury.

AREAS COVERED

This review summarizes the evidence from clinical trials evaluating pharmacological agents as adjuncts to standard reperfusion therapy for ST-elevation AMI.

EXPERT OPINION

Reperfusion injury pharmacotherapy has moved from bench to bedside, with clinical evaluation and ongoing clinical trials providing us with valuable insights into the shortcomings of current research in establishing successful treatments for reducing reperfusion injury. There is a need to address some key issues that may be leading to lack of translation of cardioprotection seen in basic models to the clinical setting. These issues are discussed in the Expert opinion section.

Early statin treatment prior to primary PCI for acute myocardial infarction: REPERATOR, a randomized placebo-controlled pilot trial

OBJECTIVE

The aim of this pilot study was to determine whether early atorvastatin treatment will reduce left ventricle (LV) remodeling, infarct size, and improve microvascular perfusion.

BACKGROUND

In animal studies, early statin therapy reduces reperfusion injury after a percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI).

METHODS

Forty-two consecutive patients (82% male, mean age 61.2 ± 9.8) who underwent a primary PCI for a first ST-elevated AMI were randomized for pretreatment with atorvastatin 80 mg (n = 20) or placebo (n = 22) and continued with the same dosage daily for 1 week. All patients received atorvastatin 80 mg once daily 7 days after primary PCI. The LV function and infarct size were measured by magnetic resonance imaging within 1 day, at 1 week, and 3 months follow up. The primary endpoint was the end-systolic volume index (ESVI) at 3 months. Secondary endpoints were global LV function measurements, myocardial infarct size, biochemical cardiac markers, TIMI flow, and ST-T elevation resolution.

RESULTS

ESVI 3 months after AMI was 25.1 mL/m(2) in the atorvastatin arm and 25.0 mL/m(2) in the placebo arm (P = 0.74). The differences in change from baseline to 3 months follow up in global LV function and myocardial infarct size did not differ between both treatment arms. Furthermore, biochemical markers, TIMI flow, and ST-T elevation resolution did not differ between atorvastatin and placebo arm.

CONCLUSIONS

In this pilot study, pretreatment with atorvastatin in an acute myocardial infarction does not result in an improved cardiac function, microvascular perfusion, or decreased myocardial infarct size.

Comparison of case fatality rates for acute myocardial infarction in weekday vs weekend admissions in South Korea

BACKGROUND

According to recent reports, reduced weekend staffing in hospitals may lead to a lower intensity of management of patients with acute conditions such as acute myocardial infarction (AMI). The present study evaluated differences in the case fatality rate of Korean patients admitted with AMI on weekdays vs those admitted on weekends.

METHODS AND RESULTS

The dataset was constructed from the Korea National Health Insurance Claims Database. The study population was 97,466 patients who were admitted to a hospital in Korea from 2003 to 2007 with AMI. Patients admitted on weekends had a higher 30-day fatality rate (20.1% vs 17.3%) than did those admitted on weekdays. Differences in the 30-day fatality rate were significant after adjusting for baseline characteristics and the severity of disease (odds ratio (OR), 1.21; 95% confidence interval (CI), 1.16-1.26). However, the 30-day fatality rate was insignificantly different after additional adjustment for medical or invasive management (OR 1.05; 95%CI 0.99-1.11).

CONCLUSIONS

Differences in the case fatality rate of AMI patients admitted on weekdays and on weekends in Korea are caused by differences in the rate of performance of medical or invasive procedures.

Partial vs full coverage for tandem lesions in culprit vessel during primary coronary intervention in patients with acute ST-elevation myocardial infarction--the PERFECT-AMI study

BACKGROUND

The efficacy of partial vs full coverage for tandem lesions in the culprit vessel during primary percutaneous coronary intervention (PCI) after ST-elevation myocardial infarction (STEMI) was compared in the present study.

METHODS AND RESULTS

The 76 patients with STEMI and tandem lesions in the culprit vessel were randomized to receive stent implantation for an occluded/culprit lesion only (partial group) or complete coverage of lesions (full group). After PCI, patients in the partial group had more complete ST-segment resolution (STR) at 90 min (60.5% vs 28.9%, P=0.006), Thrombosis In Myocardial Infarction (TIMI) flow grade 3 (68.4% vs 28.9%, P=0.001), and myocardial blush grade 3 (42.1% vs 15.8%, P=0.04) than those in the full group. At 6 months, the major adverse cardiac events-free survival rate did not differ significantly between groups, but left ventricular (LV) ejection fraction was improved in the partial group. Multivariate analysis revealed pre-procedural TIMI flow grade >1 and door-to-balloon time <90 min were positively associated with complete STR at 90 min, whereas full coverage for tandem lesions was an independent factor for poor STR (odds ratio 2.58, 95% confidence interval 1.08-5.42, P=0.03).

CONCLUSIONS

For acute STEMI patients with tandem lesions in the culprit vessel, primary stenting for the occluded lesion only is beneficial in improving myocardial perfusion and LV function.