A Canadian research team, led by Dr. Jacob Udell, a cardiologist at Women's College Hospital and the University of Toronto, discovered the the influenza vaccine could potentially be a critical treatment for keeping up heart health and avoiding cardiovascular events such as heart attacks and strokes.
The researchers examined published clinical trials on this subject that date back to the 1960s.
The team found in those who had the vaccine, the risk reduction was significant. They saw a 50 percent decrease in the risk of a major cardiac happening (stroke, heart attack, or cardiac death), after being compared with placebo after one year of follow-up. Similarly, a pattern was seen in those with the flu vaccine, a decrease in death from any cause (about 40 percent).
The flu vaccine decreased cardiovascular events and cardiovascular death in people with or without heart disease.
The research analyzed a total of 3,227 patients, with close to an equal division between patients with and without diagnosed heart disease. Half of the participants were randomly chosen to have a flu vaccine and those that did not, generally received a placebo vaccine.
Dr. Udell thinks these results confirm the current guideline recommendations for flu vaccination of people with a prior heart attack, but for more reasons than just decreasing flu risk. Despite the promising results of a reduction in non-fatal cardiac events, he recommends a larger, longer, multi-national study that could thoroughly show the vaccine's effectiveness to decrease fatal cardiac events and save lives.
A more comprehensive study could encourage use of the vaccine, which Udell thinks is still extremely low. Less than 50 percent of the general population receive the flu vaccine.
A survey taken earlier this year by B.C. and Quebec Lung Associations found that 36 percent of Canadians documented receiving a flu shot in 2011. Also, the 2008 Adult National Immunization Coverage Survey reported that vaccination rates for adults between 18 and 64 years old, with a chronic medical condition, is scarce, at 35 percent. Seniors who are non-institutionalized, aged 65 and older have more coverage, at 66 percent.
Since that 2006 survey, rates for both groups have deceased slightly and just miss the 80 percent national targets for flu vaccine coverage in adults under age 65 with chronic conditions and in seniors, according to the Public Health Agency of Canada's National Advisory Committee on Immunization (NACI).
A second study, by cardiologists Dr. Ramanan Kumareswaran and Sheldon Singh from Sunnybrook Health Sciences Center investigated the use of the flu vaccine in patients with implantable cardiac defibrillators (ICDs). They found those who received the shot had fewer harmful events.
Dr. Kumareswaran says, "Anecdotes suggest that patients have more ICD shocks during flu season. We were trying to figure out what we can do to reduce the amount of shocks in (our clinic's) ICD population during the flu season."
Patients with ICDs that had appointments at the Sunnybrook Hospital ICD clinic between September 1, 2011 and Novemeber 31, 2011, answered a questionnaire that shows their demographics, health status, if they have gotten a flu shot in the past year, and opinions about the vaccine.
The health charts of the patients were examined to measure all ICD therapies in five months leading up to the 2010 flu season, and for three months during the 2010-2011 flu season.
In total, 230 patients ages 70 to 74 years filled out surveys. Of these patients 179 (78 percent), reported having the vaccination in the previous year. More than 20 percent did not get the vaccine.
Patients without flu vaccines had a pattern toward experiencing more ICD therapies. Of the patients, 10.6 percent who had the vaccine, received at least one ICD therapy during flu season, in contrast to the 13.7 percent of those who did not receive the flu vaccine.
Dr. Singh explains:
"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. We would like to look at this on a larger scale to determine whether or not our results can be replicated. We're in the process to determine how best to do that."
An ICD is a small battery-powered electrical impulse generator that is put in patients who have a risk of sudden cardiac death. It works by identifying cardiac arrhythmia and fixes it by sending a jolt of electricity or strengthening the heart rate to restore a healthy rhythm once an irregular heart beat has been found.
Every year, approximately 5,000 Canadians get ICDs and as of now, there are 100,000 Canadians that have them.
Dr. Beth Abramson, Heart and Stroke Foundation spokesperson, believes these studies verify National Advisory Committee for Immunization recommendations for the use of the flu vaccine in people who are at a high risk of getting influenza related issues, including patients with diabetes or heart disease, as well as those with a risk of developing complications.
She advises an influenza vaccination for people at a high risk of flu-related complications or hospitalization including:
- people with heart conditions
- people over 65 years of age
- people with diabetes
- people with a BMI at or above 40
- children or adults treated with ASA
Dr. Abramson concludes, "In addition to leading a heart healthy life, having an annual flu shot could be another easy way to help prevent cardiac events."
Written by Kelly Fitzgerald