|Year : 2008 | Volume
| Issue : 4 | Page : 134-136
|Date of Web Publication||17-Jun-2010|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
. Cardiovascular News. Heart Views 2008;9:134-6
Cardiac Resynchronization Therapy Reduces the Risk of Hospitalizations in Patients with Advanced Heart Failure (COMPANION) Trial
In the Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure (COMPANION) trial, 1520 patients with advanced heart failure were assigned in a 1:2:2 ratio to optimal pharmacological therapy or optimal pharmacological therapy plus cardiac resynchronization therapy (CRT-P) or CRT with defibrillator (CRT-D). Use of CRT-P and CRT-D was associated with a significant reduction in combined risk of death or all-cause hospitalizations. Because mortality also was significantly reduced (optimal pharmacological therapy versus CRT-D only), an assessment of the true reduction in hospitalization rates must consider the competing risk of death and varying follow-up times.
To overcome the challenges of comparing treatment groups, investigators used a nonparametric test of right-censored recurrent events that accounts for multiple hospital admissions, differential follow-up time between treatment groups, and death as a competing risk. An end-point committee adjudicated and classified all hospitalizations. Compared with optimal pharmacological therapy, CRT-P and CRT-D were associated with a 21% and 25% reduction in all-cause, 34% and 37% reduction in cardiac, and 44% and 41% reduction in heart failure hospital admissions per patient-year of follow-up, respectively. Similar reductions were seen in hospitalization days per patient-year. The reduction in hospitalization rate for heart failure in the CRT groups appeared within days of randomization and remained sustained. Noncardiac hospitalization rates were not different between groups.
Use of CRT with or without a defibrillator in advanced heart failure patients was associated with marked reductions in all-cause, cardiac, and heart failure hospitalization rates in an analysis that accounted for the competing risk of mortality and unequal follow-up time.
Antiplatelet Therapy and Stent Thrombosis After Sirolimus-Eluting Stent Implantation
The influences of antiplatelet therapy discontinuation on the risk of stent thrombosis and long-term clinical outcomes after drug-eluting stent implantation have not yet been addressed adequately.
In an observational study in Japan, 2-year outcomes were assessed in 10 778 patients undergoing sirolimus-eluting stent implantation. Data on status of antiplatelet therapy during follow-up were collected prospectively. Incidences of definite stent thrombosis were 0.34% at 30 days, 0.54% at 1 year, and 0.77% at 2 years. Thienopyridine use was maintained in 97%, 62%, and 50% of patients at 30 days, 1 year, and 2 years, respectively. Patients who discontinued both thienopyridine and aspirin had a significantly higher rate of stent thrombosis than those who continued both in the intervals of 31 to 180 days, 181 to 365 days, and 366 to 548 days after stent implantation (1.76% versus 0.1%, P<0.001; 0.72% versus 0.07%, P = 0.02; and 2.1% versus 0.14%, P = 0.004, respectively). When discontinuation of aspirin was taken into account, patients who discontinued thienopyridine only did not have an excess of stent thrombosis in any of the time intervals studied. Adjusted rates of death or myocardial infarction at 24 months were 4.1% for patients taking thienopyridine and 4.1% for patients not taking thienopyridine (P = 0.99) in the 6-month landmark analysis.
Discontinuation of both thienopyridine and aspirin, but not discontinuation of thienopyridine therapy only, was associated with an increased risk of stent thrombosis. Landmark analysis did not suggest an apparent clinical benefit of thienopyridine use beyond 6 months after sirolimus-eluting stent implantation.
Electrophysiological Effects of Late Percutaneous Coronary Intervention for Infarct-Related Coronary Artery Occlusion
The Occluded Artery Trial-Electrophysiological Mechanisms (OAT-EP) tested the hypothesis that opening a persistently occluded infarct-related artery by percutaneous coronary intervention and stenting (PCI) after the acute phase of myocardial infarction compared with optimal medical therapy alone reduces markers of vulnerability to ventricular arrhythmias.
Between April 2003 and December 2005, 300 patients with an occluded native infarct-related artery 3 to 28 days (median, 12 days) after myocardial infarction were randomized to PCI or optimal medical therapy. Ten-minute digital Holter recordings were obtained before randomization, at 30 days, and at 1 year. The primary end point was the change in a 1, a nonlinear heart rate variability parameter, between baseline and 1 year. Major secondary end points were the changes in the filtered QRS duration on the signal-averaged ECG and variability in T-wave morphology (T-wave variability) between baseline and 1 year. There were no significant differences in the changes in 1 (-0.04; 95% CI, -0.12 to 0.04), filtered QRS (2.2 ms; 95% CI, -1.4 to 5.9 ms), or T-wave variability (3.0 μV; 95% CI, -4.8 to 10.7 μV) between the PCI and medical therapy groups (medical therapy change minus PCI change). Multivariable analysis revealed that the results were unchanged after adjustment for baseline clinical variables and medication treatments during the Holter recordings.
PCI with stenting of a persistently occluded infarct-related artery during the subacute phase after myocardial infarction compared with medical therapy alone had no significant effect on changes in heart rate variability, the time-domain signal-averaged ECG, or T-wave variability during the first year after myocardial infarction. These findings are consistent with the lack of clinical benefit, including no reduction in sudden death, with PCI for stable patients with persistently occluded infarct-related arteries after myocardial infarction in the main OA.
Comparison of Early Surgery Versus Conventional Treatment in Asymptomatic Severe Mitral Regurgitation
The optimal timing of surgical intervention in asymptomatic patients with severe mitral regurgitation is unclear. We therefore compared the long-term results of early surgery with a conventional treatment strategy.
From 1996 to 2005, 447 consecutive asymptomatic patients (253 men, age 50±15 years) with severe degenerative mitral regurgitation and preserved left ventricular function were evaluated prospectively. The end point was defined as the composite of operative mortality, cardiac death, repeat mitral valve surgery, and urgent admission due to congestive heart failure during follow-up. Early surgery was performed on 161 patients (operated group), and the conventional treatment strategy was used for 286 patients (conventional treatment group). There were no significant differences between the 2 groups in terms of age, gender, euroSCORE (European System for Cardiac Operative Risk Evaluation), or ejection fraction.
During a median follow-up of 1988 days, there were 2 repeat surgeries and no cardiac deaths or operative mortality in the operated group compared with 12 cardiac deaths, 1 repeat surgery, and 22 admissions for congestive heart failure in the conventional treatment group. The estimated actuarial 7-year cardiac mortality rate was 0% in the operated group and 5±2% in the conventional treatment group (P = 0.008), and for 127 propensity score-matched pairs, the estimated actuarial 7-year event-free survival rate was significantly higher in the operated than in the conventional treatment group (99±1% versus 85±4%, P = 0.007). In the conventional treatment group, baseline grade of pulmonary hypertension (hazard ratio 1.87, 95% CI 1.22 to 2.87, P = 0.003), age (hazard ratio 1.02, 95% CI 1.01 to 1.04, P = 0.005), and effective regurgitant orifice area (hazard ratio 2.06, 95% CI 1.11 to 3.82, P = 0.02) were independent variables that predicted late development of surgical indications or congestive heart failure on Cox multivariate analysis.
Compared with conservative management, the strategy of early surgery was associated with an improved long-term event rate by decreasing cardiac mortality and congestive heart failure hospitalization more effectively in patients with severe degenerative mitral regurgitation. Early surgery may therefore further improve clinical outcomes in asymptomatic severe mitral regurgitation with preserved left ventricular systolic function and a high likelihood of mitral valve repair.
Determinants of Prolonged QT Interval and Their Contribution to Sudden Death Risk in Coronary Artery Disease (The Oregon Sudden Unexpected Death Study)
In a recent cohort study, prolongation of the corrected QT interval (QTc) was associated with an independent increased risk of sudden cardiac death (SCD). We evaluated determinants of prolonged QTc and the relationship of prolonged QTc to SCD risk among patients with coronary artery disease in the general population.
A case-control design was used. Cases were SCD patients with coronary artery disease among a metropolitan area of 1 000 000 residents (2002 to 2006); controls were area residents with coronary artery disease but no history of SCD. All cases were required to have an ECG suitable for QTc analysis before and unrelated to the occurrence of SCD. A total of 373 cases and 309 controls met criteria for analysis. Mean QTc was significantly longer in cases than in controls (450±45 versus 433±37 ms; P < 0.0001). In a multivariate model, gender, diabetes mellitus, and QTc-prolonging drugs were significant determinants of QTc prolongation in controls. In a logistic regression model predicting SCD, diabetes mellitus (odds ratio, 1.97; 95% confidence interval, 1.32 to 2.96) and use of QTc-prolonging drugs (odds ratio, 2.90; 95% confidence interval, 1.92 to 4.37) were significant predictors of SCD among subjects with normal or borderline QTc. However, abnormally prolonged QTc in the absence of diabetes and QT-prolonging medications was the strongest predictor of SCD (odds ratio, 5.53; 95% confidence interval, 3.20 to 9.57).
Diabetes mellitus and QTc-affecting drugs determined QTc prolongation and were predictors of SCD in coronary artery disease. However, idiopathic abnormal QTc prolongation was associated with 5-fold increased odds of SCD. A continued search for novel determinants of QTc prolongation such as genomic factors is likely to enhance risk stratification for SCD in coronary artery disease.
Fasting Blood Glucose and the Risk of Stroke and Myocardial Infarction
A total of 652 901 Korean men aged 30 to 64 years from the Korean National Health Insurance System were categorized into 8 groups by fasting blood glucose (FBG) level at baseline and were followed up for cardiovascular diseases occurrence during 1992-2001.
Over the follow-up period of 8.8 years, 10 954 stroke and 3766 myocardial infarction events occurred. In age-adjusted analyses, there was evidence of linear associations between FBG and myocardial infarction, ischemic stroke, and intracerebral hemorrhagic stroke. However, with additional adjustment for socioeconomic position, behaviors, and other cardiovascular disease risk factors, the associations with myocardial infarction and intracerebral hemorrhagic stroke were markedly attenuated with increased risk only at the highest FBG levels ( 7.5 mmol/L). With full adjustment, the association with ischemic stroke persisted; a linear increase in the risk of ischemic stroke was observed from FBG level of 5.6 mmol/L. When the analyses were repeated with those persons who had been diagnosed with diabetes removed, there was no evidence of associations of FBG with intracerebral hemorrhagic stroke, but the association with ischemic stroke persisted.
In this Korean male population, the association with high FBG differed between ischemic stroke, intracerebral hemorrhagic stroke, and myocardial infarction. The linear increase in the risk of ischemic stroke, independently of other cardiovascular risk factors, was observed at a level below the current FBG criteria for impaired fasting glucose ( 5.6 mmol/L). However, for other cardiovascular diseases, the current cutoff for diagnosing diabetes appropriately identified Korean men at risk.
Early Stent Thrombosis in Patients with Acute Coronary Syndromes Treated with Drug-Eluting and Bare Metal Stents
The clinical and angiographic predictors of early (<30 days) stent thrombosis (ST) have not been reported in high-risk patients with acute coronary syndromes.
Qualitative and quantitative coronary angiographic analyses were performed in 3405 patients with moderate- and high-risk acute coronary syndromes in whom stents were implanted in the prospective randomized Acute Catheterization and Urgent Intervention Triage Strategy (ACUITY) trial, including 3043 patients (89.4%) in whom drug-eluting stents were implanted. Within 30 days, definite or probable ST occurred in 48 patients (1.4%). ST rates were not significantly different in patients treated with bare metal stents compared with drug-eluting stents (1.4% versus 1.4%; P=1.00) or with heparin plus glycoprotein IIb/IIIa inhibitors (1.1%) compared with bivalirudin with or without IIb/IIIa inhibitors (1.6% and 1.5%, respectively; P = 0.26 and P = 0.37, respectively). Compared with patients without ST, patients with ST more frequently had insulin-requiring diabetes mellitus and baseline renal insufficiency, a greater overall burden of coronary atherosclerosis, and suboptimal final angiographic results. ST also was more common in patients without preprocedural thienopyridine administration and with inconsistent antiplatelet drug use within 30 days. By multivariable analysis, the strongest independent predictors of definite ST were a smaller final stent minimal lumen diameter, a lack of preprocedural thienopyridine administration, the extent of coronary artery disease, and higher baseline hemoglobin level.
Occurring in nearly 1 in 70 patients, early ST is relatively common in acute coronary syndromes, occurs with similar frequency after anticoagulation with either heparin plus glycoprotein IIb/IIIa inhibitors or bivalirudin with or without IIb/IIIa inhibitors, and is predicted by diffuse atherosclerosis, suboptimal angiographic results, and inadequate pharmacotherapy.
Acute Kidney Injury after Cardiac Surgery
Acute kidney injury (AKI) after cardiac surgery is a major health issue. Lacking effective therapies, risk factor modification may offer a means of preventing this complication. The objective of the present study was to identify and determine the prognostic importance of such risk factors.
Data from a multicenter cohort of 3500 adult patients who underwent cardiac surgery at 7 hospitals during 2004 were analyzed (using multivariable logistic regression modeling) to determine the independent relationships between 3 thresholds of AKI (> 25%, > 50%, and >75% decrease in estimated glomerular filtration rate within 1 week of surgery or need for postoperative dialysis) with death rates, as well as to identify modifiable risk factors for AKI. The 3 thresholds of AKI occurred in 24% (n = 829), 7% (n = 228), and 3% (n = 119) of the cohort, respectively. All 3 thresholds were independently associated with a > 4-fold increase in the odds of death and could be predicted with several perioperative variables, including preoperative intra-aortic balloon pump use, urgent surgery, and prolonged cardiopulmonary bypass. In particular, 3 potentially modifiable variables were also independently and strongly associated with AKI. These were preoperative anemia, perioperative red blood cell transfusions, and surgical reexploration.
AKI after cardiac surgery is highly prevalent and prognostically important. Therapies aimed at mitigating preoperative anemia, perioperative red blood cell transfusions, and surgical reexploration may offer protection against this complication.
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