Herpes zoster linked to increased cardiovascular risk

By Jane Lewis 
Herpes zoster infection is associated with transiently increased rates of stroke and myocardial infarction (MI), particularly in the first week following diagnosis, and vaccination does not appear to modify this association, suggests new research published online in PLOS Medicine.

According to the researchers, the study is the first to use the self-controlled case series method, rather than cohort designs (which are limited by the potential for confounding because they compare outcomes between individuals, rather than within individuals).

Speaking to Medicine Today, Professor Dominic Dwyer, medical virologist at Westmead Hospital, Sydney, said the study confirms the increased risk of cerebral and cardiac disease in the immediate aftermath of shingles, in addition to the pain and discomfort of the acute dermatomal rash.

The study investigated 42,954 US adults aged 65 years or above who had been diagnosed with herpes zoster and had had an ischaemic stroke, and 24,237 who had been diagnosed with herpes zoster and an MI during a five-year period. Comparing age-adjusted incidence ratios for stroke and MI calculated for time periods both before and after zoster diagnosis, the researchers found a 2.4-fold increased rate of ischaemic stroke, and a 1.7-fold increased rate of MI, in the first week after zoster diagnosis, with rates decreasing gradually over a six-month period.

Multiple biological mechanisms are likely to be involved in the increased risk of acute cardiovascular events following zoster, the researchers suggested, adding that the association observed between zoster and MI is ‘suggestive of a systemic association rather than one localized to the brain.’

No association was found between zoster vaccination and the incidence ratio of either ischaemic stroke or MI in the first four weeks after vaccination. However, the study’s power to assess an association was limited by the relatively low rate of vaccination (9%) among participants, the researchers acknowledged.

‘Our findings provide useful information that may help to prevent acute cardiovascular events in older people,’ they concluded.

‘Herpes zoster infection is a common and unpleasant illness, with a range of complications,’ commented Professor Dwyer. ‘Use of the zoster vaccine in older adults decreases the likelihood of developing shingles, and, should shingles develop, antiviral drugs given within the first 72 hours can reduce the severity of pain as well as the likelihood of postherpetic neuralgia. However, whether these interventions reduce the association of MI and stroke after shingles remains to be determined.’

PLOS Med 2015; doi:10.1371/journal.pmed.1001919.

Picture credit: © ISM/SPL. Shingles.