Flu vaccination helpful to patients with implantable cardiac defibrillators

A couple of days ago I reported that the flu vaccination not only prevents the flu itself, but it may also reduce risk of certain types of heart disease and death from cardiovascular events. In another study presented at the Canadian Cardiovascular Congress meeting in Toronto, the authors stated that the flu vaccination may have a critical benefit to patients who have implantable cardiac defibrillators (ICD), a small battery-powered device that automatically detects cardiac arrhythmias, then corrects it by delivering an electrical shock that can revert ventricular fibrillation, and that has been extended to include both atrial and ventricular arrhythmias. 

According to study author Dr. Ramanan Kumareswaran, physicians have known that patients tend to need more ICD shocks during flu season, and wanted to investigate ways of reducing this need to rely on the device.

The study surveyed 229 patients who had come in for appointments related to their ICD care from September through November 2011. Of those patients, 179 (78%) reported that they had received the influenza vaccination in the previous year. Patients who received the influenza vaccine were older than those who did not (70.8 vs. 64.8 years, P=0.0005). Finally, there was no difference in the prevalence of coronary artery disease, diabetes, renal disease, and prior stroke in patients the vaccinated and un vaccinated patients.

Some of the results of the survey were:

  • Patients who received the flu vaccine were more likely to reject statements such as, “The Flu shot is not effective” and “The Flu shot will make me sick” compared to individuals not receiving the influenza vaccine.
  • Vaccinated individuals also planned to obtain the influenza vaccine in the upcoming year. 
  • Thirty nine (17.0%) individuals in the overall cohort received at least one ICD therapy during the two pre-defined periods – 10.6% who received the influenza vaccine received at least 1 ICD therapy during influenza season compared to 13.7% who did NOT receive the influenza vaccine (P=NS). 
  • About 13.7% of the unvaccinated patients experienced at least one ICD therapy (meaning that the ICD device had to adjust the heart rate) during the flu season compared to the 10.6% of patients who were vaccinated. This wasn’t a significant difference. However, the average number of ICD therapies per person during influenza season was greater in individuals not receiving the influenza vaccination (0.45 therapies) compared to individuals who did receive the influenza (0.14 therapies).

“What is interesting is that if this is consistent over time, it could be of significant benefit to our patient population who already have compromised survival to start with,” wrote Dr. Sheldon Singh, one of the study’s authors.

The authors concluded:

A large proportion of patients with ICDs receive the influenza vaccine. Receipt of the influenza vaccine may be associated with a reduction in ICD therapies during influenza season.

Now, as I’ve said with the other study, from the same Canadian Cardiovascular Congress meeting, that showed that a link between getting the flu vaccination and reduced cardiovascular events, these studies are not peer reviewed. They aren’t published yet in journals. They haven’t been repeated by other researchers. But the study seems to be sound, and it is a very sound argument for getting the flu vaccination if you have serious cardiovascular issues.

And don’t listen to those myths about the flu vaccine, they just aren’t true. No, they aren’t true.

Vaccines save lives.

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