CARDIOVASCULAR NEWS
16,588 patients in the first 6 hours of evolving ST-segment elevation myocardial infarction (MI) were randomly assigned to standard-dose reteplase or half-dose reteplase and full dose abciximab. The primary endpoint was 30-day mortality and secondary endpoints were various complications of MI.
At 30 days, mortality in the reteplase group was 5.9% compared with 5.6% in the combined reteplase and abciximab group, p=0.43.
Although there were fewer secondary complications of myocardial infarction including reinfarction in the combination group, this was counterbalanced by increased non-intracranial bleeding complications.
(Lancet 2001; 357: 1905-14)
Short episodes of ischemia and reperfusion protect the myocardium from the damage induced by episodes of sustained ischemia. Early ischemic pre conditioning is apparent within minutes and lasts 2 to 3 hours. A second phase, delayed preconditioning, reappears 12 to 24 hours later and
lasts for 3 to 4 days. Ischemic preconditioning could reduce infarct size and other harmful consequences of ischemia/reperfusion and it is the model of numerous experimental studies.
Leeson and colleagues report that a 4-hour infusion of nitroglycerin (NTG) 24 hours before angioplasty provides cardioprotective effects. There was reduction in ST-segment elevation in those who received NTG infusion 24 hours pre-angioplasty. In addition, regional wall motion score by
echocardiography and chest pain score improved. Thus, a) NTG 24 hours before angioplasty rendered the myocardium relatively resistant to ischemia; b) the degree of this cardioprotective effect was comparable to that afforded by the ischemia associated with the first balloon inflation in
control subjects (early phase of ischemic preconditioning). Collateral flow did not differ between control and NTG-pretreated patients, indicating that the enhanced tolerance to ischemia in NTG-pretreated patients cannot be accounted for by baseline differences in collateral function.
This is the first report that a late preconditioning effect can be recruited pharmacologically in humans. The results suggest that prophylactic administration of nitrates could be a novel approach to the protection of the ischemic myocardium in patients. (Circulation. 2001;103:2935.)
The ACC/AHA guidelines state that exercise testing within three years of successful
coronary revascularization (CR) is not useful.
A study was undertaken to evaluate the ACC/AHA
recommendation. 1,678 patients randomized to
CR by either angioplasty or bypass surgery were
required to take symptom-limited treadmill tests
one, three and five years after revascularization.
Patients who took the test after CR at each
specified time had a much lower subsequent two-year
mortality than those who did not (1.9% vs. 9.4%,
3.5% vs. 12.6% and 3.3% vs. 11.0% at one, three
and five years, respectively, (p < 0.0001 for
each). Exercise parameters at the one- and three-year
test did not improve a multivariable model of
survival after including clinical parameters.
Exercising to Bruce stage 3 or generating a
Duke score >?6 were independently predictive
of two-year survival after the five-year test.
ST depression on the one-year test was associated
with more revascularizations (Relative Risk
= 1.6; p < 0.001). Patients with stable multivessel
coronary disease who took a protocol-mandated
exercise test at one, three and five years after
revascularization were at low risk for mortality
in the two years subsequent to each test. Exercise
parameters did not improve prediction of mortality
in the two years after the one- and three-year
tests. The ACC/AHA guidelines on exercise testing
after CR (no value for routine testing in stable
patients for three years after revascularization)
are supported by these results. (J Am Coll Cardiol.
2001;38(1):136 – 142)
The association of silent ischemia with coronary risk in a population-based
sample of men with no prior coronary heart disease
(CHD) was studied. Silent ischemia was defined
as ST depression during and after maximal symptom-limited
exercise test. Subjects were followed for 10
years. Silent ischemia during exercise was associated
with a 5.9-fold CHD mortality in smokers; 3.8-fold
in hypercholesterolemic men and 4.7-fold in
hypertensive men adjusting for other risk factors.
The respective relative risks (RRs) of any acute
coronary event were 3.0 (95% CI 1.7 to 5.1),
1.9 (95% CI 1.2 to 3.1) and 2.2 (95% CI 1.4
to 3.5). These associations were weaker in men
without these risk factors. Furthermore, silent
ischemia after exercise was a stronger predictor
for the risk of acute coronary events and CHD
death in smokers, in hypercholesterolemic, and
hypertensive men than in men without risk factors.
The study highlights the importance of exercise
testing to identify asymptomatic high risk men
who could benefit from risk reduction and preventive
measures. (J Am Coll Cardiol; 2001;38:1:72 –
79)
A simple blood test to aid in the diagnosis and treatment of patients with
congestive heart failure could have a favorable
impact in the management of such patients in
terms of costs and quality of life. B-type natriuretic
peptide (BNP) is synthesized in the cardiac
ventricles. Its level has been found to correlate
with left ventricular pressure, amount of dyspnea,
and the state of neurohormonal modulation, thus
making peptide the first potential “white count”
for heart failure. Data indicate that serial
testing of BNP should be helpful in patients
presenting to urgent care clinics with dyspnea.
BNP may also serve as a screen for patients
referred for echocardiography. A low BNP level
makes left ventricular systolic and diastolic
dysfunction highly unlikely. In patients admitted
with decompensated heart failure, BNP measurements
may obviate the need for invasive hemodynamic
monitoring and help tailor treatment, thus improving
their in-hospital management. In the outpatient
setting, BNP maybe of critical importance in
titration of therapies as well as in assessing
the sate of neurohormonal compensation of the
patient. (Journal of Cardiac Failure. 2001;
7(2):183-93)
Air pollution have been associated with increased admissions for cardiovascular
and respiratory diseases. To evaluate the effect
of short-term exposure to fine-particulate air
pollution on the risk of acute myocardial infarction
(MI), investigators compared data from The Determinants
of Myocardial Infarction Onset Study (Onset
Study) with hourly measurements of fine particles
in Boston, USA. The researchers used a case-cross-over
design to specifically assess the risk of exposure
to high levels of pollution and the timing of
the impact of this exposure on the onset of
MI. The risk of MI increased proportionally
with elevated levels of air pollution within
a few hours and one day after exposure. (Circulation.
2001;103:2810.)
Risk factors for stroke in patients with non-ST-elevation acute coronary syndrome
(ACS) were investigated. Data from 18,151 patients
enrolled in the OASIS program (Organization
To Assess Strategies for Ischemic Syndromes)
were analyzed. 238 patients (1.3%) had a stroke
over a 6-month follow-up. Those who experienced
stroke had a 4-fold increase in 6-month mortality
(27% versus 6.3%, P=<0.001). A Cox multivariate
regression analysis identified CABG surgery
as the most important predictor of stroke, followed
by history of stroke, diabetes mellitus, older
age, higher heart rate, and on-site catheterization
facility. There was no significant excess in
stroke in patients undergoing percutaneous coronary
intervention (P=0.21). Patients who underwent
early CABG surgery were at a substantially increased
risk compared with those who had later CABG
(3.3% versus 1.6%; P=0.003) or who had no surgery
(3.3% versus 1.1%; P=0.0001). The study demonstrates
that although stroke in patients with ACS was
uncommon, it was a serious event associated
with high mortality. The performance of early
CABG was a powerful independent predictor of
stroke. (Circulation. 2001;104:269.)
921 consecutive patients undergoing cardiac surgery underwent epiaortic echocardiographic evaluation of the ascending aorta before surgical manipulation. The presence of calcification, location of atheroma,
extent of the disease and clinical variables including postoperative stroke were recorded prospectively.
26.2% of the patients had atherosclerosis of the ascending aorta. In 44.4% of those with aortic atherosclerosis, more than one of 12 possible segments was involved. Logistic regression showed that atherosclerotic
disease in the ascending aorta was the most important predictive factor for postoperative stroke. The middle-lateral segment was found to be an independent predictive factor for postoperative stroke, with a relative risk of 26% (p = 0.04).
The incidence of stroke was 1.8% in patients without atherosclerotic disease of the ascending aorta, and 8.7% in patients with the disease (p < 0.0001). (J Am Coll Cardiol. 2001;38(1):131 – 135)
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