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Influenza vaccination may have the added benefit of reducing the risk of heart attacks. Also, a study questions the belief that seizures may act as triggers for sudden cardiac arrest in patients with epilepsy.
Flu Vaccine May Protect Against Heart Attack
Although influenza infection was not a significant predictor of heart attack after accounting for other factors, receipt of the flu vaccine was associated with a reduced likelihood of having an acute myocardial infarction (MI), a case-control study showed.
Epidemiological evidence has pointed to an association between influenza and cardiovascular complications, particularly acute MI and death, and , of the University of New South Wales in Sydney, and colleagues explored the issue further in a study of 275 patients with acute MI and 284 outpatients without acute MI at a hospital in Sydney. All of the patients were 40 or older and about half had received flu vaccine.
As reported , evidence of influenza infection was found in 12.4% of MI patients and 6.7% of the controls (odds ratio 1.97, 95% CI 1.09-3.54). After adjustment for potential confounders, influenza infection was not associated with acute MI, but influenza vaccination was. Those who were vaccinated were 45% less likely to have an acute MI (OR 0.55, 95% CI 0.35-0.85), a finding consistent with a prior study.
"The role of an expanded vaccination program for adults over 50 years of age, which would capture a significant proportion of people at risk of acute MI should be explored by further research," the authors wrote. "At the least, clinicians should be aware of influenza and infection as an underlying and poorly diagnosed precipitant or comorbidity in hospitalized patients and of the preventive benefit of influenza vaccine for patients at risk for acute MI."
Seizures May Not Be Primary Cardiac Arrest Triggers
Two-thirds of patients with a history of epilepsy and a witnessed sudden cardiac arrest did not have any seizure activity before the event, researchers found.
The finding, reported online in , "[challenges] conventional clinical wisdom," according to , of Cedars-Sinai Medical Center in Los Angeles, and colleagues, who explored the issue because sudden cardiac arrest is a major cause of death in patients with epilepsy.
The researchers looked at data from the Oregon Sudden Unexpected Death Study. Of 2,417 patients with sudden cardiac arrest over a 10-year period, 4.4% had epilepsy. Only 34% of the epileptic patients had evidence of seizures before the arrest.
Survival to hospital discharge following an attempted resuscitation was significantly lower among patients with a history of epilepsy (2.7% versus 11.9%, P=0.014). Epileptic patients were less likely to present with ventricular tachycardia/ventricular fibrillation compared with those without epilepsy (26% versus 44%, P=0.002), despite average response times of a little under 7 minutes in both groups.
"The significantly worse rate of survival from sudden cardiac arrest in epilepsy patients warrants urgent investigation," Chugh and colleagues wrote.
Poor Renal Function May Worsen Outcomes in Afib
Among anticoagulated patients with nonvalvular atrial fibrillation, those with the worst renal function carried a greater risk for stroke or systemic embolism, a post-hoc analysis of the AMADEUS trial showed.
Compared with patients with a creatinine clearance of at least 60 mL/min, those with lower values had significantly elevated risks of stroke or systemic embolism (hazard ratio 2.27, 95% CI 1.14-4.52), as well as major bleeding (HR 1.58, 95% CI 1.05-2.39), , of the University of Birmingham Center for Cardiovascular Sciences in Birmingham, England, and colleagues reported online in the .
The researchers looked into how renal function might affect outcomes among anticoagulated patients with atrial fibrillation using pooled data from the idraparinux and vitamin K antagonist arms of the AMADEUS trial, which was stopped early because of excess bleeding in the idraparinux group.
The annual rate of stroke or systemic embolism increased with worsening creatinine clearance (P<.001 for trend):
- Greater than 90 mL/min: 0.6%
- 60 to 90 mL/min: 0.8%
- Less than 60 mL/min: 2.2%
Adding creatinine clearance as a variable in stroke risk scores resulted in a significant 26% net reclassification improvement (P=0.02), but did not affect discrimination ability.
"Our results ... suggest that patients with chronic kidney disease might benefit from more aggressive stroke prevention strategies," the authors wrote. "Such strategies include more intensive INR monitoring to ascertain strict INR control or more effective oral anticoagulation regimes ... when indicated."
Group Wants Clopidogrel Warning
Public Citizen, a watchdog group, against using clopidogrel (Plavix) beyond 1 year after drug-eluting stent implantation because of the risk of major bleeding and a lack of evidence supporting the effectiveness of prolonged use.
The group has started a petition seeking a boxed warning on the drug's label stating the following: "The continuation of clopidogrel for longer than 12 months following percutaneous insertion of a drug-eluting stent is of questionable additional benefit in preventing adverse cardiac events but continues to carry an increased risk of major and minor bleeding, even in those who have no known bleeding tendency."
The petitions was submitted jointly with a physician whose wife after taking clopidogrel for more than 2 years after receiving a drug-eluting.
, founder of and senior adviser to Public Citizen's Health Research Group, said in a statement,"The FDA should promptly warn against prolonged use on the product's labeling, require a warning in patient medication guides, and ask the manufacturers to send a letter warning physicians."