Outcome of ST-elevation myocardial infarction versus non-ST-elevation acute coronary syndrome treated with titanium-nitride-oxide-coated versus everolimus-eluting stents: insights from the BASE-ACS trial

AIM

The BASE-ACS trial demonstrated an outcome of titanium-nitride-oxide-coated bioactive stents (BAS) that was statistically non-inferior to that of everolimus-eluting stents (EES) at 12-month follow-up, in patients presenting with acute coronary syndrome (ACS) who underwent early percutaneous coronary intervention (PCI). We explored a post-hoc analysis of the 12-month outcome of the BASE-ACS trial in the subgroup of patients with ST-elevation myocardial infarction (STEMI) versus non-ST-elevation ACS (non-STEACS).

METHODS

A total of 827 patients with ACS (321 STEMI) were randomly assigned to receive either BAS or EES. The primary endpoint was a composite of cardiac death, non-fatal myocardial infarction (MI) and ischemia-driven target lesion revascularization (TLR) at 12-month follow-up.

RESULTS

The 12-month cumulative incidence of the primary endpoint was similar between the two subgroups (9% versus 9.5%, in STEMI versus non-STEACS patients respectively, P=0.90). The 12-month rate of cardiac death was significantly higher in the STEMI subgroup as compared with the non-STEACS subgroup (2.8 versus 0.6%, respectively, P=0.01). However, the rates of non-fatal MI, ischemia-driven TLR, definite stent thrombosis, and non-cardiac death were all statistically matched between the two subgroups (P>0.05 for all).

CONCLUSION

In the current post-hoc analysis of the BASE-ACS trial based on the infarction type, the 12-month outcome of patients who underwent early PCI for ACS was slightly worse in the setting of STEMI as compared with non-STEACS, as reflected by a significantly higher rate of cardiac death.

Protective effects of simvastatin on coronary artery function in swine with acute infection

BACKGROUND

The risk for coronary events may rise during acute infection. Perturbation in coronary endothelial function emerges as one important link. We investigated whether simvastatin could protect the coronary arterial function from the adverse effects of acute infection in swine.

METHODS

Coronary endothelium-dependent and -independent vasomotor responses were assessed by Doppler velocimetry in 12 Chlamydia pneumoniae-infected and 6 sham-infected swine 2 weeks after intratracheal inoculation. Half of animals from the infection group were pre-treated with simvastatin (80 mg daily), while the remaining animals received placebo. The treatment was started 2 weeks prior to inoculation and continued until the end of the study. ANOVA was used for statistical calculations. Data are mean+/-S.D.

RESULTS

All animals inoculated with C. pneumoniae developed IgM antibodies against this organism. As compared to noninfected animals, peak-to-baseline coronary flow velocity (CFV) ratio after bradykinin was significantly decreased in infected animals regardless of statin treatment (p=0.01). Intracoronary 10(-6) M acetylcholine caused slight dilatory responses in both noninfected and infected-treated animals (CFV ratio: 1.6+/-0.2 and 1.4+/-0.2, respectively; p>0.1), while a velocity drop (CFV ratio: 0.7+/-0.1; p<0.01 versus noninfected-infected and treated), indicating constriction, was observed in infected-nontreated animals; 10(-5) M acetylcholine caused vasoconstriction in all animals, with a significantly more prolonged response in the infected-nontreated group (p<0.01). Intracoronary adenosine and SNP induced similar dilatory responses in all groups (p>0.5). There were no differences in markers of systemic inflammation (fibrinogen, amyloid, and CRP) and lipid profile (HDL, LDL and total cholesterol) between the groups (p>0.2).

CONCLUSION

Acute infection is associated with impairment of the muscarinic and kinin-related reactivity of coronary circulation. These functional abnormalities are in part prevented by simvastatin through mechanisms unrelated to lipid lowering.

Acute Chlamydia pneumoniae infection causes coronary endothelial dysfunction in pigs

BACKGROUND

Coronary endothelial dysfunction contributes to the pathogenesis of acute coronary syndromes (ACSs). Acute Chlamydia pneumoniae infection has been epidemiologically associated with ACS. In this study, we investigated whether acute C. pneumoniae infection could alter the endothelial vasomotor function of porcine coronary vessels.

METHODS AND RESULTS

Twenty pigs, 7-9 kg in weight, were inoculated intratracheally with C. pneumoniae (n=12) or saline (n=8), and investigated at 3 days (five infected/four non-infected) and 2 weeks (5+2 infected/four non-infected) after inoculation. The endothelium-dependent reactivity of coronary microcirculation was assessed at both time points by measuring peak coronary flow velocity (CFV) in response to bradykinin, before and after infusions with glutathione, an antioxidant, and L-arginine, a substrate for nitric oxide synthase (NOS). CFV after bradykinin was significantly decreased in infected animals at both time points. At 2 weeks, both glutathione and L-arginine significantly improved CFV after bradykinin. CFV after sodium nitroprusside (SNP) was similar in both groups. At 3 days, the relaxation responses of bradykinin-induced pre-contracted left anterior descending (LAD) coronary rings to bradykinin were significantly less in infected animals. N(G)-nitro-L-arginine-methyl-ester, an NOS inhibitor, had significantly greater inhibitory effect on bradykinin-induced relaxation in infected animals. Plasma nitrate-nitrite and fibrinogen, and NOS activity from LAD coronary samples were significantly increased in infected animals.

CONCLUSION

Acute C. pneumoniae infection causes endothelial dysfunction of both resistance and epicardial coronary vessels, and favours a pro-coagulant status. These effects could in part account for the epidemiologically suggested association between acute infection and ACS.

Rupture of the atherosclerotic plaque: does a good animal model exist?

By its very nature, rupture of the atherosclerotic plaque is difficult to study directly in humans. A good animal model would help us not only to understand how rupture occurs but also to design and test treatments to prevent it from happening. However, several difficulties surround existing models of plaque rupture, including the need for radical interventions to produce the rupture, lack of direct evidence of rupture per se, and absence of convincing evidence of platelet- and fibrin-rich thrombus at the rupture site. At the present time, attention should therefore focus on the processes of plaque breakdown and thrombus formation in humans, whereas the use of animal models should probably be reserved for studying the function of particular genes and for investigating isolated features of plaques, such as the relationship between cap thickness and plaque stability.