Seniors who develop the painful rash known as shingles appear to face a short-term increase in their risk for having a stroke or heart attack, new research indicates.
The finding was based on the tracking of heart health among more than 67,000 newly diagnosed shingles patients who were aged 65 and older.
The analysis revealed that stroke risk more than doubled in the first week following a shingles diagnosis, with heart attack risk also climbing, though not by quite as much. The risk for both appeared to return to normal within six months.
"The study highlights when patients with shingles may be most vulnerable," explained study author Caroline Minassian, a research fellow in the faculty of epidemiology and population health at the London School of Hygiene & Tropical Medicine in England.
"If we know when these events are more likely to happen, this may potentially help to prevent strokes and heart attacks in older people," she added.
Minassian and her colleagues reported their findings in the Dec. 15 issue of the journal PLOS Medicine.
Shingles is caused by the same virus that causes chickenpox (varicella zoster). Anyone who has ever had chickenpox faces some risk of getting shingles, according to the U.S. National Institute of Neurological Disorders and Stroke. More than 1 million Americans develop the disease every year, the researchers said.
Many of those are seniors, who are typically diagnosed after the onset of mild to serious burning or tingling pain on one side of their body. The rashes and blisters that ensue are treatable with antiviral medications. In addition, a vaccine (Zostavax) that was released in 2006 can cut shingles risk in half, while also significantly reducing symptom severity when shingles does strike.
The study focused on nearly 43,000 Medicare recipients diagnosed with both shingles and a stroke between 2006 and 2011. Roughly 24,000 shingles patients who experienced a heart attack in the same timeframe were also included.
Average patient age was 80 years, roughly two-thirds were women and about 90 percent were white. Very few (between 2 percent and 3 percent) had received the shingles vaccine before diagnosis, the study authors said.
Stroke and heart attack occurrence were tracked during five different periods of time in the year following a shingles diagnosis: week one; weeks two to four; weeks five to 12; weeks 13 to 26; and six months.
Compared with patient risk prior to a shingles diagnosis, stroke risk was seen to rise "significantly" for up to three months following a shingles diagnosis. The biggest bump -- amounting to more than a twofold rise in risk -- occurred during the first week. That risk dissipated after six months, the investigators found.
An increase in heart attack risk followed a similar trajectory, with almost a doubling in risk occurring during the first week following a shingles diagnosis, the findings showed.
The study team said there was no evidence that shingles vaccinations had either prevented or aggravated stroke or heart attack risk.
"However, this finding requires further study due to low vaccine uptake in our study population," Minassian said.
As for exactly why shingles threatens heart health, Minassian said that the study "did not look at the mechanisms involved in the associations." And the findings do not prove a cause-and-effect relationship between the virus and cardiovascular problems.
"However, possible reasons might include the overall higher level of inflammation in the body associated with a viral infection, or [virus-induced] blood vessel damage," she said. "Acute increases in blood pressure relating to shingles-associated pain or stress may also play a role."
Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, pointed out that the study by Minassian and colleagues is not the first to identify a possible link between shingles and a general bump in the risk for heart trouble.
The difference, he said, is that "this new study finds a significant association early after the onset of shingles."
But shingles, said Fonarow, is not alone in its apparent ability to undermine cardiovascular health. Influenza, community-acquired pneumonia and urinary tract infections have all been previously linked to a similar rise in the risk for heart complications, he explained.