Houston, TX - New research published this week has shown that influenza epidemics are associated with a rise in autopsy-confirmed coronary deaths, leading investigators to conclude that influenza vaccination should be advocated for all patients at high risk of developing cardiovascular disease [1].

"This is a very large study, and one of the unique things about it is that we looked specifically at autopsy, which minimized bias due to misclassification of the disease," lead investigator Dr Mohammad Madjid (Texas Heart Institute, Houston) told heartwire. "Looking at all the evidence over the past two or three decades, there is no question that flu triggers heart attacks, and there is little question over the preventive role of flu vaccines. We continue to push this because doctors are simply not practicing what we are preaching."

The new report is published online April 18, 2007 in the European Heart Journal. Senior investigator of the paper is Dr Ward Casscells (University of Texas, Houston), who, along with Madjid, has spent many years researching this subject and lobbying the American Heart Association (AHA) and the American College of Cardiology (ACC) to endorse flu vaccine for patients with coronary heart disease (CHD). Just last year the AHA and ACC outlined recommendations advising doctors to administer influenza vaccines to everyone with cardiovascular disease. The European Society of Cardiology (ESC), however, has not yet followed the lead of its US counterparts and currently does not recommend flu vaccination for secondary prevention. Even in the US, says Madjid, only about 60% of patients who should be vaccinated actually receive the vaccine.

Looking at autopsy-proven coronary deaths, Madjid and colleagues investigated the impact of influenza epidemics on CHD death between 1993 and 2000 in St Petersburg, Russia. Very few in this population, Madjid told heartwire, were vaccinated against the flu or receiving statins, and this allowed investigators to observe the effects of a flu epidemic in the absence of these medications.

We continue to push this because doctors are simply not practicing what we are preaching.

Overall, 11 892 people died from acute MI and 23 000 died from chronic ischemic heart disease (IHD). In every year, a peak of AMI and chronic IHD deaths were observed and coincided with the influenza epidemic and peak acute respiratory-disease activity, a disease that that often accompanies the flu. When investigators compared the average epidemic weeks, when flu was at its peak, with average off-season weeks, the risk of dying from AMI and chronic IHD increased by 30% and 10%, respectively. Similar patterns were observed for men, women, subjects 50 years of age and older, and subjects 70 years of age and older.

"The message is that flu is a killer," said Madjid. "It's very serious. Second, flu vaccines can save lives, and we have to use them. My concern is that we haven't been paying enough attention to the risk. There are no drug reps going around advocating the vaccine, it's not a drug-eluting stent, it doesn't have Big Pharma's marketing behind it, but time and time again we have shown that the vaccine is a safe, effective, and inexpensive way to prevent heart attacks."

Each year, between 10% and 20% of the population is hit with influenza, and Madjid estimates that more than 90 000 deaths per year in the US are the result of influenza-triggered MIs. More alarming, he said, is the potential for a flu pandemic to strike. During a pandemic, twice as many people die of MI than of pneumonia, a finding that is as surprising as it is overlooked.

"In the next pandemic, we are going to see a significant rise in the number of heart attacks," said Madjid. "Are we prepared for it? No, we're not." He added that during influenza pandemics, the elderly and those with CHD or multiple coronary risk factors would be most affected.

Based on the data, Madjid told heartwire that he believes the ESC should follow the recommendations of the ACC and AHA to ensure that all European patients with CHD are vaccinated. This vaccine, he says, would be most beneficial in underprivileged patients not taking various cardioprotective medications due to their prohibitive cost or lack of access to medical care.