CARDIOVASCULAR NEWS
B-type
natriuretic petide risk marker for inducible ischemia
in patients with CAD
Inflammation as a Risk Factor for Atrial Fibrillation
Premature atherosclerosis in SLE independent of
traditional risks for CAD
Successful
Catheter RF Ablation of repetitive ventricular
tachyarryhtmias feasible and may prevent
resistant
electrical storm post myocardial Infarction
Milrinone Facilitates Resuscitation From Cardiac
Arrest and Attenuates Postresuscitation
Myocardial Infarction
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.
Circulation 2003;108:2987
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.
Circulation 2003;108:3006
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
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.
Circulation 2003;108:3011
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.
Circulation 2003;108:3031
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