INSIDE THIS ISSUE OF JACC
Inside This Issue of JACC
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Sirolimus-Paclitaxel Comparison
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Lower Restenosis Rates in Small Vessels With Sirolimus Stents.
Whereas the restenosis rates are known to be higher for bare-metal stents in smaller vessels, the relationship between vessel size and restenosis for drug-eluting stents is less clear. Elezi and colleagues randomized over 2,000 patients undergoing elective percutaneous coronary intervention to either sirolimus-eluting stents (SES) or paclitaxel-eluting stents (PES). The rates of target lesion revascularization (TLR) after 6- and 9-month angiographic follow-up were then compared based on initial vessel size. The rate of TLR was similar regardless of vessel size for SES, and was similar between SES and PES for vessels >2.4 mm. However, for vessels <2.4 mm, the rate of TLR was twice as high with PES versus SES. This study suggests that for most interventions, the choice of SES or PES is one of operator preference, but SES appears superior to PES for small vessels. See page 1304. See figure.
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Intervention in Acute Coronary Syndromes
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Meta-Analysis Confirms That Early Invasive Strategy Reduces Mortality.
Although some contemporary studies have found mortality benefits with an early invasive strategy in patients with acute coronary syndromes, others have shown no benefit, and older studies suggested increased hazards. In this meta-analysis that included 7 large trials with over 8,000 patients, there was a 25% reduction in all-cause mortality and a 17% reduction in non-fatal myocardial infarction with an early invasive strategy. There was also a 31% reduction in rehospitalization for unstable angina. This analysis suggests that managing acute coronary syndromes with an early invasive strategy improves long-term survival without increasing early adverse events when compared with an ischemia-driven protocol. See page 1319.
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Intervention in Acute Coronary Syndromes
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Improved Clinical Outcomes With Higher Clopidogrel Loading Doses.
Although several studies have shown that a 600-mg loading dose of clopidogrel results in more platelet inhibition than a 300-mg dose, there has been a paucity of data on clinical outcomes. Cuisset and colleagues randomized subjects with acute coronary syndromes to either 300- or 600-mg loading doses of clopidogrel. Subjects then underwent percutaneous coronary intervention at least 12 h later. Blood was collected to determine adenosine diphosphate-induced platelet reactivity prior to percutaneous coronary intervention. The higher loading dose reduced the likelihood of high platelet reactivity (15% vs. 25%); this also correlated with better 30-day clinical outcomes. This study demonstrates that a 600-mg loading dose for patients with acute coronary syndromes results in more complete platelet inhibition and improved clinical outcomes. See page 1339. See figure.
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Percutaneous Valve Prosthesis
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Novel Design of Endovascular Valve Allows for Repositioning After Deployment.
One concern with previously published reports of endovascular valve replacement is the inability to reposition the valve once it has been deployed. Zegdi and colleagues describe a novel design where a porcine stentless valve is mounted on a self-expanding nitinol stent and is passed through a sheath. The stent is compressed or expanded via 2 sutures that can be manipulated through the sheath. In an experimental protocol, the valve was safely delivered and adequately positioned or repositioned in 5 sheep. This novel stent design allows percutaneous valves to be positioned and repositioned, which should improve the success rates for endovascular valve repair procedures. See page 1365. See figure.
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Heart Failure
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Famotidine as a Novel Therapy for CHF.
Recent evidence has suggested that histamine may have depressed effects on cardiac function. The H2 histamine receptor is known to be a Gs-coupled receptor that signals through cAMP, a pathway similar to that of cardiac beta-adrenoceptors. Kim and colleagues hypothesized that an H2 receptor blocker may have salutary effects similar to beta-blockers. In both a retrospective chart review and a prospective placebo-controlled study, famotidine was associated with decreased plasma levels of brain natriuretic peptide, improved New York Heart Association functional class, and improved echocardiographic parameters. Larger studies will be needed to confirm that famotidine is a simple and effective treatment for chronic heart failure, with a mechanism similar to beta-blockers. See page 1378.
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Heart Rhythm Disorders
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"Indeterminate" T-Wave Alternans Studies Are High Risk.
The microvolt T-wave alternans (MTWA) test, which uses a graded exercise study to look for alterations in the polarity of T-wave repolarization, has been proposed as a potential discriminator of patients at high or low risk for sudden cardiac death. One of this test’s main pitfalls has been a high rate of "indeterminate" results. Kaufman and colleagues reviewed over 500 MTWA tests with clinical follow-up. Nearly one-third of tests were classified as "indeterminate"; patients with "indeterminate" test results had mortality rates at least as high as those with positive results. In over 80% of tests with indeterminate results, the reason was patient-related (either frequent ectopy during the test or an inability to achieve and sustain a heart rate >105 beats/min). This report lends further credence to the argument that "indeterminate" tests should be considered "abnormal," and that MTWA is useful as a discriminator between high- and low-risk sub-groups. See page 1399. See figure.
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Heart Rhythm Disorders
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Pregnancy Safe for Females With LQT1 Mutations.
Patients with LQT1 mutations have prolonged QTc at rest and may develop ventricular arrhythmias during vigorous exercise or emotional stress. This is due to impairment in the IKs current, which disrupts the normal ability to shorten ventricular repolarization as heart rate increases. Thus, any condition that augments sympathetic activity may lead to life-threatening arrhythmias, and there has been concern about the safety of pregnancy in these individuals. Heradien and colleagues studied the outcomes of pregnancies in 22 families with known LQT1 mutations. There were 3 (2.6%) cardiac events (2 cardiac arrests) in the 115 LQT1 pregnancies; all occurred in females with previous symptoms who were not taking beta-blocker therapy. The authors conclude that for patients with no previous symptoms, pregnancy is safe. For those with previous symptoms, beta-blocker therapy may reduce the likelihood of cardiac events and appears safe for the fetus. See page 1410.
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Orthostatic Hypotension
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Compressive Bandages Are Effective for Progressive Orthostatic Hypotension.
Progressive orthostatic hypotension occurs in elderly people with prolonged standing and can be quite debilitating; the currently available therapies have limited efficacy or are relatively contraindicated in elderly patients with comorbidities. Podoleanu and colleagues studied the use of leg and abdominal compression stockings in both a sham-controlled tilt table test and in real-life scenarios. The stockings were effective in preventing tilt table-induced symptoms and decreasing blood pressure. The stockings were well tolerated, with significant decreases in the Specific Symptom Scale Questionnaire for Orthostatic Intolerance. These bandages may be a simple and effective therapy for progressive orthostatic hypotension. See page 1425. See figure.
Related Article
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Vessel Size and Outcome After Coronary Drug-Eluting Stent Placement: Results From a Large Cohort of Patients Treated With Sirolimus- or Paclitaxel-Eluting Stents
- Shpend Elezi, Alban Dibra, Julinda Mehilli, Jürgen Pache, Rainer Wessely, Albert Schömig, and Adnan Kastrati
J. Am. Coll. Cardiol. 2006 48: 1304-1309.
[Abstract]
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Intervention in Acute Coronary...
Percutaneous Valve Prosthesis
