|Year : 2003 | Volume
| Issue : 3 | Page : 2
|Date of Web Publication||22-Jun-2010|
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
. Cardiovascular News. Heart Views 2003;4:2
B-type natriuretic petide risk marker for inducible ischemia in patients with CAD
In patients with symptoms of heart failure, elevations in B-type natriuretic peptide (BNP) accurately identify ventricular dysfunction. However, BNP levels are not specific for ventricular dysfunction in patients who do not have overt symptoms of heart failure, suggesting that other cardiac processes such as myocardial ischemia may also cause elevations in BNP.
To determine whether BNP elevations are associated with myocardial ischemia, investigators measured plasma BNP levels before performing exercise treadmill testing with stress echocardiography in outpatients with stable coronary disease. Of the 355 participants, 113 (32%) had inducible ischemia. Compared with participants in the lowest BNP quartile (0 to 16.4 pg/mL), those in the highest quartile of BNP (105 pg/mL) had double the risk of inducible ischemia. The relation between elevated BNP levels and inducible ischemia was especially evident in the 206 participants who had a history of myocardial infarction and was absent in those without a history of myocardial infarction. This association between BNP levels and inducible ischemia remained strong after adjustment for measures of systolic and diastolic dysfunction.
The study concluded that elevated levels of BNP are independently associated with inducible ischemia among outpatients with stable coronary disease, particularly among those with a history of myocardial infarction. The observed association between BNP levels and ischemia may explain why tests for BNP are not specific for ventricular dysfunction among patients with coronary disease.
Inflammation as a Risk Factor for Atrial Fibrillation
The presence of systemic inflammation determined by elevations in C-reactive protein (CRP) has been associated with persistence of atrial fibrillation (AF). The relationship between CRP and prediction of AF has not been studied in a large population-based cohort.
CRP measurement and cardiovascular assessment were performed at baseline in 5806 subjects enrolled in the Cardiovascular Health Study. Patients were followed up for a mean of 6.9±1.6 (median 7.8) years. AF was identified by self-reported history and ECGs at baseline and by ECGs and hospital discharge diagnoses at follow-up. Univariate and multivariate analyses were used to assess CRP as a predictor of baseline and future development of AF. At baseline, 315 subjects (5%) had AF. Compared with subjects in the first CRP quartile (<0.97 mg/L), subjects in the fourth quartile (>3.41 mg/L) had more AF (7.4% versus 3.7%, adjusted OR 1.8, 95% CI 1.2 to 2.5; P=0.002). Of 5491 subjects without AF at baseline, 897 (16%) developed AF during follow-up. Baseline CRP predicted higher risk for developing future AF. When treated as a continuous variable, elevated CRP predicted increased risk for developing future AF (adjusted hazard ratio for 1-SD increase, 1.24; 95% CI 1.11 to 1.40; P<0.001).
CRP is not only associated with the presence of AF but may also predict patients at increased risk for future development of AF.
Premature atherosclerosis in SLE independent of traditional risks for CAD
Although systemic lupus erythematosus is associated with premature myocardial infarction, the prevalence of underlying atherosclerosis and its relation to traditional risk factors for cardiovascular disease and lupus-related factors have not been examined in a case-control study.
Researchers assessed the risk factors for cardiovascular disease in 197 patients with lupus and 19117 matched controls. Carotid ultrasonography, and echocardiography were performed. The patients were also evaluated with respect to their clinical and serologic features, inflammatory mediators, and disease treatment.
The risk factors for cardiovascular disease were similar among patients and controls. Atherosclerosis (carotid plaque) was more prevalent among patients than the controls (37.1 percent vs. 15.2 percent, P<0.001). In multivariate analysis, only older age, the presence of systemic lupus erythematosus (odds ratio, 4.8; 95 percent confidence interval, 2.6 to 8.7), and a higher serum cholesterol level were independently related to the presence of plaque. As compared with patients without plaque, patients with plaque were older, had a longer duration of disease and more disease-related damage, and were less likely to have multiple autoantibodies or to have been treated with prednisone, cyclophosphamide, or hydroxychloroquine. In multivariate analyses including patients with lupus, independent predictors of plaque were a longer duration of disease, a higher damage-index score, a lower incidence of the use of cyclophosphamide, and the absence of anti-Smith antibodies. The study concluded that atherosclerosis occurs prematurely in patients with systemic lupus erythematosus and is independent of traditional risk factors for cardiovascular disease. The clinical profile of patients with lupus and atherosclerosis suggests a role for disease-related factors in atherogenesis and underscores the need for trials of more focused and effective antiinflammatory therapy.
New Engl J Med 2003;349:2399
Successful Catheter RF Ablation of repetitive ventricular tachyarryhtmias feasible and may prevent resistant electrical storm post myocardial Infarction
Researchers in Germany report on 4 patients (aged 57 to 77 years; 3 men) who developed drug-refractory, repetitive ventricular tachyarrhythmias after acute myocardial infarction (MI). All episodes of ventricular arrhythmias were triggered by monomorphic ventricular premature beats (VPBs) with right bundle-branch block morphology (RBBB).
Left ventricular (LV) mapping was performed to attempt radiofrequency (RF) ablation of the triggering VPBs. Activation mapping of the clinical VPBs demonstrated the earliest activation in the anteromedial LV in 1 patient and in the inferomedial LV in 2 patients. Short, high-frequency, low-amplitude potentials were recorded that preceded the onset of each extrasystole by a maximum of 126 to 160 ms. At the same site, a Purkinje potential was documented that preceded the onset of the QRS complex by 23 to 26 ms during sinus rhythm. In 1 patient, only pace mapping was attempted to identify areas of interest in the LV. Six to 30 RF applications abolished all local Purkinje potentials at the site of earliest activation and/or perfect pace mapping and suppressed VPBs in all patients. No episode of ventricular tachycardia or fibrillation has recurred for 33, 14, 6, and 5 months in patients 1, 2, 3, and 4, respectively.
Incessant ventricular tachyarrhythmias after MI may be triggered by VPBs. RF ablation of the triggering VPBs is feasible and can prevent drug-resistant electrical storm, even after acute MI. Catheter ablation of the triggering VPBs may be used as a bailout therapy in these patients.
Milrinone Facilitates Resuscitation From Cardiac Arrest and Attenuates Postresuscitation Myocardial Dysfunction
Left ventricular (LV) dysfunction with a low cardiac index after successful CPR contributes to early death attributable to multiorgan failure. An effective treatment has not been identified. The use of milrinone, a selective phosphodiestirase III inhibitor, was investigated ast treatment for LV dysfunction after resuscitation.
Ventricular fibrillation (VF) was induced electrically in 32 swine. After 5 minutes of VF, CPR was initiated and animals were randomized to receive either saline (control group, n=16) as a bolus and infusion or milrinone 50 μg/kg as a bolus and then 0.5 μg/kg per min for 60 minutes (treatment group, n=16). After 2 minutes of CPR (total VF time, 7 minutes), countershocks were given. Coronary perfusion pressures during CPR were similar for the groups (24±2 versus 21±4 mm Hg). All animals were defibrillated; 6 of 16 control animals developed refractory postcountershock pulseless electrical activity compared with 0 of 16 treated animals (P=0.018). At 30 minutes after restoration of spontaneous circulation, stroke volume (16±3 versus 26±7 mL, P<0.01) and LV dp/dt (793±197 versus 1108±316 mm Hg/s, P<0.02) were higher in the treatment group. Similar differences were observed 60 minutes after restoration of spontaneous circulation. Significant differences in heart rates between groups were not observed, and peripheral vascular resistance was significantly greater in the control group 30 and 60 minutes after resuscitation.
Milrinone facilitates resuscitation from prolonged VF and attenuates LV dysfunction after resuscitation without worsening major determinants of myocardial oxygen demand.
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