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Can a Heart Infection Cause A Heart Attack?

Cardiovascular diseases are the main cause of death in developed countries. They represent 20% of global mortality in the world. The intervention on traditional risk factors and the classic treatment of ischemic heart disease have not managed to reverse the dramatic consequences of this disease. In recent years, research has focused on the etiopathogenesis (medical term that refers to the origin of a disease and its mechanisms) of atherosclerosis (it is a vascular alteration characterized by hardening, increased thickness and loss of elasticity of the arterial walls) in order to find new therapeutic targets that help us improve the control of atherosclerotic disease.

It has long been known that the classic risk factors of ischemic heart disease (sex, age, smoking, hypercholesterolemia, hypertension, and diabetes mellitus) account for only 50% of clinically apparent cases of atherosclerosis. Patients with similar levels of cardiovascular risk experience different courses of the disease and it is also known that the rates of myocardial infarction and sudden death increase in winter and after epidemics of influenza. All these findings have supported the hypothesis that infections could condition an increased risk of atherosclerosis.

In addition to all these considerations, we must bear in mind that the variability of each individual can condition a different response to these aggressions.

According to the inflammatory response that triggers the individual, along with the immune response to the different pathogens, there will be a greater or lesser susceptibility to the formation of atherosclerosis due to an infectious stimulus.

In the genesis of atherosclerosis, different microorganisms have been involved. Of all of them, Citomegalovirus, Chlamydia pneumoniae, and Helicobacter pylori are the ones on which there is greater evidence.

Atherosclerosis and Helicobacter pylori

This bacterium resides in the cells of the gastric mucosa and is transmitted by a fecal-oral mechanism. It is present in practically 100% of duodenal ulcers and in 60% of gastric ulcers. H. pylori infection is usually acquired in childhood and antibodies against it will persist until later in life, so the prevalence of antibodies against Helicobacter in the general population is very high, around 40% at 50 years old.

Numerous studies have confirmed an association between positive serology against H. pylori and atherosclerotic disease. Most of them have been performed in patients with classic ischemic heart disease and some on cerebral atherosclerosis.

Atherosclerosis and Citomegalovirus

The first infectious agents related to atherosclerosis were viruses, and of all of them, the family of herpesviruses.

It can be transmitted through the fecal-oral, oral-oral or parenteral route. It is believed that their natural habitat is leukocytes, although this is not well established. The infection in immunocompetent individuals remains in a latent state throughout life, although it may undergo reactivation, asymptomatic in most cases. The prevalence in the general population is very high; more than 50% of the population over 35 years of age has antibodies against the virus, and as these age increases, these figures rise to 70% in those over 70 years. CMV infection is correlated with a low socioeconomic status, with immunosuppression states and with age.

Most studies show a positive association between CMV infection and atherosclerosis.

Atherosclerosis and Chlamydia pneumoniae

This bacterium is transmitted through respiratory secretions and is believed to persist inside alveolar macrophages. It is the second pathogen causing atypical pneumonias, responsible for 10% of cases. The primary infection by C. pneumoniae usually occurs at early ages of life and reinfections are extraordinarily frequent. Approximately 50% of those over 50 years have positive serology against C. pneumoniae and its prevalence correlates with age, socioeconomic status, smoking habit and periodic epidemics.

The results of epidemiological studies show a strong association between positive serology against C. pneumoniae and atherosclerosis.

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Can a Heart Infection Cause A Heart Attack?