Prognostic Significance of Markers in Combination
The combination of pro-brain natriuretic peptide (NT-proBNP) and creatinine clearance proved the predictor of prognosis in patients with acute coronary syndrome in a subset analysis of the Global Utility of Strategies To Open occluded arteries IV (GUSTO-IV) trial in this week’s issue of Circulation: Journal of the American Heart Association (Circulation. 2003;108:275–281).
In this study, NT-proBNP, troponin T, and C-reactive protein were analyzed in blood samples obtained an average of 9.5 hours from the start of symptoms in 6809 acute coronary syndrome patients in the trial. The levels of NT-proBNP were correlated with age, female gender, low body weight, diabetes, kidney failure, history of heart attack, heart failure, heart rate, ongoing heart muscle damage, and time since the onset of ischemia.
As levels of NT-proBNP increased, the researchers found that mortality rate at 1 year also increased. For example, the patients with levels of the marker in the lowest quartile had a death rate of 1.8%. In the second quartile, the death rate was 3.9%; in the third, 7.7%; and in the highest quartile, 19.2%. In fact, the researchers found that NT-proBNP had the strongest relation to 1-year mortality among the markers tested.
Troponin T, C-reactive protein, heart rate, creatinine clearance, and ST-segment depression also correlated with 1-year mortality rate. Troponin T, creatinine clearance, and ST-segment depression were the only markers to be independently related to the risk of future heart attack.
Combining NT-proBNP and creatinine clearance, however, provided the best prediction of death at 1 year. The risk of death was 25.7% in the group with both measurements in the highest quartile and only 0.3% in the group with both measurements in the lowest quartile.
In an accompanying editorial, David A. Morrow, MD, MPH, and Eugene Braunwald, MD, of the Cardiovascular Division in the Department of Medicine at Harvard Medical School and Brigham and Women’s Hospital in Boston, Mass, noted that the report by Stefan K. James, MD, of the Academic Hospital in Uppsala, Sweden, and his colleagues “adds substantially to the accumulating evidence that a multi-marker strategy, employing a pathobiologically diverse set of biomarkers, is likely to add importantly to cardiac-specific troponin alone in risk assessment of patients with ACS [acute coronary syndrome]” (Circulation. 2003;108:250–252).
“The clinical application of cardiac biomarkers in ACS is no longer limited to establishing or refuting the diagnosis of myocardial necrosis,” they wrote. “Cardiac biomarkers provide a convenient and noninvasive means to gain insight into the underlying causes and consequences of ACS that mediate the risk of recurrent events and may be targets for specific therapeutic interventions.”
The Race Factor in Life and Death Among Patients Who Have Suffered a Cardiac Arrest
Elderly black patients who suffer a cardiac arrest are more likely to die after hospital discharge than their white counterparts, said researchers from the Center for Primary Care and Outcomes Research in Stanford, Calif, in a report in this week’s issue of Circulation (Circulation. 2003;108:286–291).
The researchers, led by Peter W. Groeneveld, MD, MS, studied the records of 5948 elderly Medicare patients who survived to hospital discharge between 1990 and 1999. Of those patients, 5429 were white and 519 were black.
The study showed that the hazard ratio for mortality was 1.30 for blacks aged 66 to 74 years compared with whites in the same age range. When patients received a variety of cardiac procedures, the hazard ratio for blacks dropped to 1.23 compared with whites. The mortality hazard ratio when implantable cardioverter defibrillators were used was 0.53 for whites and 0.50 for blacks.
In conclusion, the researchers noted that “there is racial disparity in long-term mortality among elderly cardiac arrest survivors. Both black and white patients benefited from ICD [implantable cardioverter defibrillator] implantation, but blacks were less likely to undergo this potentially life-saving procedure. Lower rates of cardiac procedures may explain in part the lower survival rates among black patients.”
CYPHER Stent Warning Released by Cordis Corporation
In a “Health Care Professional Letter,” Cordis Corporation has warned of the rare but potential risk of thrombosis associated with use of its CYPHER Sirolimus-Eluting Coronary Stent. The device is the first drug-eluting stent approved for use in the United States.
The company estimates that as many as 50 000 have received the stent to date. The US Food and Drug Administration (FDA) has received 47 Medical Device Reports of stent thrombosis that occurred at the time of implantation or within a few days after implantation.
According to the agency and the company, the FDA is reviewing the reports and working closely with Cordis to determine the causes of the thrombosis and reduce its incidence. The FDA said it is at present unclear what effect the stent has on thrombosis risk.
The FDA has required that the company undertake studies after approval to track adverse events and to determine the rate of thrombosis in clinical practice. Current recommendations to reduce the incidence of adverse events include:
Selection of the appropriate stent size. The stent size should match the diameter of the vessel as closely as possible.
Selection of appropriate patients for implantation. The stent is indicated for improving coronary luminal diameter in previously untreated vessels and is not indicated for the treatment of restenosis (reclogging of a previously stented vessel).
Use of an adequate antiplatelet regimen. Doctors are reminded to give adequate doses of medication that reduce the risk of clot formation.
Use of the proper technique for stent deployment. The stent should be fully deployed and in contact with the vessel wall. Poor stent deployment is a factor that can increase the thrombosis risk.
Another Study in Favor of Thrombolysis
Two studies in the July 5, 2003, issue of the British Medical Journal back the delivery of thrombolytics by paramedics to patients with emergency chest pain before they reach the hospital (BMJ. 2003;327:27–28; BMJ. 2003;327:22–26).
In the first study, the time to receiving thrombolytics was more than halved for patients who received thrombolytics in the ambulance compared with those in rural areas who did not receive the treatment until they reached the hospital (52 versus 125 minutes). Time to treatment for patients who received ambulance treatment was 28 minutes less than for those who received treatment in the hospital (52 versus 80 minutes).
The second study showed that paramedics could safely administer thrombolysis in the community. Sixty-four paramedics in the South Devon Healthcare Trust received training in diagnosing heart attacks and assessing whether patients should receive thrombolytics. The authors, led by Phil Keeling, MD, of the South Devon Healthcare Trust of Torquay, UK, wrote “Autonomous paramedic prehospital thrombolysis seemed feasible and safe and was associated with improved call to needle times.”