INSIDE THIS ISSUE OF JACC
Inside This Issue of JACC
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Post-Infarction Risk
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Post-MI Risk Stratification: EF, TWA, SAECG, HRT, or BRS?.
The REFINE (Risk Estimation Following Infarction, Noninvasive Evaluation) study compared several modalities to identify patients at risk of serious events post-myocardial infarction (MI). Over 300 patients with ST-segment elevation MI and an ejection fraction (EF) <50% were enrolled and studied at 3 weeks and 12 weeks post-MI. Studies performed included exercise and resting T-wave alternans (TWA) testing, signal-averaged electrocardiography (SAECG), phenylephrine-induced baroreflex sensitivity (BRS) testing, heart rate variability, and heart rate turbulence (HRT). Testing at 3 weeks was not useful, whereas testing at 10 to 14 weeks was. The 20% of patients with impaired HRT, abnormal exercise TWA, and an EF <0.50 beyond 8 weeks post-MI were 5 times more likely to die, with a negative predictive value of 95%. See page 2275.
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Post-Infarction Risk
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Baroreflex Sensitivity Predicts Long-Term Cardiovascular Mortality.
Baroreflex sensitivity (BRS) is the magnitude of the change in the heart rate induced by a transient increase in blood pressure; it is measured by giving subjects intravenous boluses of phenylephrine and then measuring changes in heart rate and blood pressure. De Ferrari and colleagues postulated that reduced BRS would identify post-myocardial infarction (MI) patients at increased risk for death. Patients who survived a ST-segment elevation MI and had an ejection fraction >35% underwent BRS testing 4 weeks post-MI and were then followed for 5 years. Cardiovascular mortality among patients with depressed BRS (<3 ms/mm Hg) was 26% compared to 2.4% in those with normal BRS, a relative risk of 11.4. A depressed BRS suggests that sympathetic activity is increased and/or unopposed by adequate vagal activity and identifies patients at high risk for death. See page 2285. See figure.
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Invasive Cardiology
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Novel Technique Allows Measurement of Coronary Artery Flow.
Aarnoudse and colleagues describe a method for volumetric measurement of coronary flow using the principles of thermodilution and a guidewire with a temperature probe. Flow can be measured anywhere the guidewire can be placed. This system was tested in dogs, where flow could be measured accurately, and then in humans, where measurements were compared with fractional flow reserve. This technique for direct measurement of blood flow in select coronary segments appears to be fairly simple to perform and provides reliable information. See page 2294. See figure.
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Preclinical Studies
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Evidence for Active Apoptosis in Atherosclerotic Lesions.
Apoptosis of macrophages and smooth muscle cells may lead to plaque rupture; caspase enzymes are key modulators of apoptosis. Sarai and colleagues studied whether caspase inhibitors would reduce apoptosis in a rabbit model of atherosclerosis. Caspase inhibitors or placebo were infused prior to imaging with technetium-labeled annexin A5, which binds to cells undergoing apoptosis. There was significantly less uptake in animals that had received caspase inhibitors, confirming both the presence of apoptosis in these lesions and its reduction with caspase inhibitors. This study demonstrates that molecular imaging can be used to quantify the rate of apoptosis in atherosclerotic lesions and that this rate can be reduced by infusing caspase inhibitors. See page 2305. See figure.
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From Around the World
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Dearth of Cardiovascular Research From Developing Countries.
Prabhakaran and colleagues studied the number and quality of cardiovascular disease (CVD) research publications from developing countries. A 55% increase in disability-adjusted life-year loss attributable to CVD in developing countries is projected between 1990 and 2020 by the Global Burden of Disease Study. This is primarily due to increasing rates of obesity and diabetes. Nevertheless, 82% of CVD-related publications were from high-income countries (HIC and HMIC), compared to only 7% in low middle- (LMIC), and 4% in low-income countries (LIC). There were no studies related to health system organization, cost effectiveness, or quality of care for CVD in LIC countries. This study suggests that there is a large unmet need for studies addressing health care delivery systems and modifiers of CVD in the developing world. See page 2322. See figure.
Related Articles
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Noninvasive Risk Assessment Early After a Myocardial Infarction: The REFINE Study
- Derek V. Exner, Katherine M. Kavanagh, Michael P. Slawnych, L. Brent Mitchell, Darlene Ramadan, Sandeep G. Aggarwal, Catherine Noullett, Allie Van Schaik, Ryan T. Mitchell, Mariko A. Shibata, Sajad Gulamhussein, James McMeekin, Wayne Tymchak, Gregory Schnell, Anne M. Gillis, Robert S. Sheldon, Gordon H. Fick, Henry J. Duff for the REFINE Investigators
J. Am. Coll. Cardiol. 2007 50: 2275-2284.
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Baroreflex Sensitivity Predicts Long-Term Cardiovascular Mortality After Myocardial Infarction Even in Patients With Preserved Left Ventricular Function
- Gaetano M. De Ferrari, Antonio Sanzo, Alessandra Bertoletti, Giuseppe Specchia, Emilio Vanoli, and Peter J. Schwartz
J. Am. Coll. Cardiol. 2007 50: 2285-2290.
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Direct Volumetric Blood Flow Measurement in Coronary Arteries by Thermodilution
- Wilbert Aarnoudse, Marcel van’t Veer, Nico H.J. Pijls, Joost ter Woorst, Steven Vercauteren, Pim Tonino, Maartje Geven, Marcel Rutten, Eduard van Hagen, Bernard de Bruyne, and Frans van de Vosse
J. Am. Coll. Cardiol. 2007 50: 2294-2304.
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Broad and Specific Caspase Inhibitor-Induced Acute Repression of Apoptosis in Atherosclerotic Lesions Evaluated by Radiolabeled Annexin A5 Imaging
- Masayoshi Sarai, Dagmar Hartung, Artiom Petrov, Jun Zhou, Navneet Narula, Leo Hofstra, Frank Kolodgie, Satoshi Isobe, Shinichiro Fujimoto, Jean-Luc Vanderheyden, Renu Virmani, Chris Reutelingsperger, Nathan D. Wong, Sudhir Gupta, and Jagat Narula
J. Am. Coll. Cardiol. 2007 50: 2305-2312.
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Global Cardiovascular Disease Research Survey
- Poornima Prabhakaran, Vamadevan S. Ajay, Dorairaj Prabhakaran, Arun Kumar Gottumukkala, J.S. Shrihari, Uma Snehi, Bijoy Joseph, and Kolli Srinath Reddy
J. Am. Coll. Cardiol. 2007 50: 2322-2328.
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Post-Infarction Risk
Post-Infarction Risk
