Study finds recent shingles infection increases the risk of myocardial infarction

By Tarun Sai LomteReviewed by Danielle Ellis, B.Sc.Mar 30 2023

In a recent study published in Open Forum Infectious Diseases, researchers assessed myocardial infarction (MI) risk after zoster infection.

Background

MI has been described as a severe cardiovascular complication after viral infections. Shingles or zoster infection is estimated to cause around one million cases yearly in the United States (US). Once infected with varicella zoster virus (VZV), it establishes latency in cranial nerves and the dorsal root ganglia, which later reactivates as herpes zoster.

Herpes zoster can cause severe sequelae, including postherpetic neuralgia. Other serious complications include meningoencephalitis, giant cell arteritis, keratitis, cranial nerve damage, myelitis, endovascular injury, and keratitis. Vaccines are available to prevent herpes zoster. Several studies link VZV infection and shingles to increased MI risk.

About the study

In the present study, researchers examined the association(s) between herpes zoster and the risk of developing MI after infection. They retrieved data from the US Department of Veteran Affairs (VA) corporate data warehouse (CDW). Patients aged 18 or older with a diagnostic history of herpes zoster who received care at the VA from January 2015 to January 2020 were included as cases.

Controls were patients with a primary care visit during the study period. The index date was the date of shingles onset or primary care appointment (for controls). The first incidence of MI after the index date was determined using the International Classification of Diseases, tenth revision (ICD-10) codes. Vaccination with Zostavax (live zoster vaccine), Shingrix (recombinant, adjuvanted zoster vaccine), or both before infection was evaluated.

Descriptive statistical analysis determined baseline demographic characteristics. Multivariate logistic regression models with backward elimination were used to estimate odds ratios and 95% confidence intervals for the risk of MI 30 days after the index date. The Wald Chi-squared test confirmed the significance of odds ratios.

Findings

Overall, the study included 2.15 million patients, with 71,912 cases and 2.09 million controls. MI occurred within 30 days in 244 (0.44%) cases and 5,782 (0.28%) controls. The mean age of zoster cases was 71.3, while controls were, on average, aged 69. Most subjects (> 91%) in either cohort were males.

Patients with a herpes zoster history were 1.35 times more likely than controls to develop MI within 30 days post-infection. Those vaccinated with at least one Shingrix vaccine dose were 18% less likely to develop MI post-index date than non-vaccinated cases. No significant differences were observed in MI rates for individuals vaccinated with Zostavax.

A previous history of MI was a significant risk factor for developing MI after the index date. Likewise, a prior congestive heart failure increased the odds of MI by 29%, while vascular disease history was associated with 14% higher odds of MI. Immunosuppressive conditions increased the odds of developing a MI by 63%.

Further, the male gender was associated with 40% higher odds of MI. The renal disease also increased the odds of MI by 56%. Finally, the researchers performed sensitivity analyses in younger (< 50 years) and older (≥ 50 years) subjects. Zoster infection elevated the odds of MI in older subjects, while Shingrix vaccination reduced the odds of MI. Odds ratios could not be computed in younger subjects due to the small sample of 78 patients with MI.

Conclusions

Taken together, the findings suggested that herpes zoster infection was associated with a greater risk of developing MI within 30 days of disease. Males, comorbid patients, and older individuals were at a higher risk of MI. Receiving the recombinant vaccine reduced the odds of MI in older patients. Vaccination remains essential to prevent herpes zoster infection and subsequent cardiovascular complications.