INSIDE THIS ISSUE OF JACC
Inside This Issue of JACC
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Acute Myocardial Infarction
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Myeloperoxidase Levels Predict Post-MI Mortality.
Myeloperoxidase (MPO) is an enzyme released from neutrophils that leads to the generation of free radicals and reactive nitrogen species. Recent studies have shown that it predicts poor outcomes in patients presenting with chest pain or acute coronary syndromes. Mocatta and colleagues studied its utility in risk stratifying 500 acute myocardial infarction (MI) patients 24 to 96 h after their infarction. Myeloperoxidase was found to be elevated in post-MI patients compared to healthy controls. Furthermore, high MPO levels were independently predictive of subsequent mortality, adding prognostic information to both brain natriuretic peptide levels and ejection fraction. This study confirms that an elevated MPO predicts a poor prognosis. See page 1993. See figure.
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Coronary Artery Disease
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Lowering LDL, Not Pleiotropic Effects, Reduces CRP.
Whereas statins are known to have anti-inflammatory effects, other studies suggest that any method of low-density lipoprotein (LDL) lowering reduces inflammatory markers. Kinlay performed a meta-analysis of 23 placebo-controlled, randomized studies that reported efficacy for both LDL reduction and change in C-reactive protein (CRP). Meta-regression analysis showed a strong correlation between the change in LDL and the change in CRP; statin therapies had no significant independent effect on CRP after adjusting for the change in LDL. This study suggests that the efficacy of statins in reducing CRP levels relates to their efficiency at lowering LDL rather than to the other metabolic pathways affected by statins. See page 2003. See figure.
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Heart Failure
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Central Sleep Apnea Doubles Mortality Risk for Those With LV Dysfunction.
There has been conflicting evidence regarding the significance of sleep apnea as a cardiac risk factor. Javaheri and colleagues followed 88 patients with systolic heart failure (ejection fraction 
45%), including sophisticated studies to diagnose and characterize central sleep apnea (CSA). The median survival of patients without CSA was twice as long as those with CSA: 90 versus 45 months. This study confirms that CSA is an independent risk factor for poor outcomes in patients with systolic heart failure. See page 2028. See figure.
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Heart Rhythm Disorders
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Characterizing Ventricular Outflow Tract Arrhythmias.
Kim and colleagues sought to compare and contrast several characteristics of idiopathic outflow tract arrhythmias. Over 100 patients with either: 1) paroxysmal sustained monomorphic ventricular tachycardia (SMVT); 2) repetitive nonsustained ventricular tachycardia (NSVT); or 3) premature ventricular contractions (PVCs) underwent electrophysiologic studies. The sites of origin of the arrhythmias were similar among the 3 groups, with over 80% originating in the right ventricular outflow tract. Sustained VT was inducible during electrophysiologic study in 78% of SMVT patients, 48% of NSVT patients, and 4% of PVC patients. This finding suggests that rather than representing distinct entities, outflow arrhythmias may be considered a continuum of a single mechanism with different presentations. See page 2035.
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Cardiac Imaging
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MDCT Can Be Used to Differentiate Idiopathic Versus Ischemic Cardiomyopathies.
Andreini and colleagues performed 16-slice multidetector computed tomography (MDCT) in 61 patients with a newly diagnosed dilated cardiomyopathy (DCM) in order to determine if MDCT can reliably distinguish ischemic from nonischemic cardiomyopathies. All patients subsequently underwent conventional coronary angiography. There were no procedural complications with MDCT, whereas there were 10 complications during or after angiography. Multidetector CT correctly identified all patients with normal or pathological coronary arteries. In conclusion, MDCT is safe and accurate for distinguishing idiopathic versus ischemic DCM and may invoke fewer complications. See page 2044.
Related Article
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Plasma Concentrations of Myeloperoxidase Predict Mortality After Myocardial Infarction
- Tessa J. Mocatta, Anna P. Pilbrow, Vicky A. Cameron, Revathy Senthilmohan, Chris M. Frampton, A. Mark Richards, and Christine C. Winterbourn
J. Am. Coll. Cardiol. 2007 49: 1993-2000.
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Acute Myocardial Infarction
Coronary Artery Disease
