Cardiology and Infectious Disease: The Road Less Travelled
By Dharmaraj Karthikesan, MD,
Fellow-in-Training at Hospital Sultanah Bahiyah, Malaysia.

Cardiology and infectious disease are often seen as separate entities. We are often hard pressed to find cardiologists with a specific interest in infectious disease.

The most common association between cardiology and infectious disease is bacterial infective endocarditis. This particular condition requires the expertise of both the cardiologist and the infectious disease physician for optimal treatment and management. Infective endocarditis, however, is not the only link between these two specialties. 

Infections leading to myocarditis is another area that is still not fully understood. Viral myocarditis has been identified as the most common infectious cause of myocarditis. Adenovirus, enterovirus and parvovirus are among the most commonly identified infections causing myocarditis. The detrimental effect on the myocardium starts with the viral infection and replication and progresses to the host immunologic response and subsequent phase of cardiac remodeling. However, it is very challenging to study the exact mechanism of these viral-mediated myocarditis in humans. Most of our understanding of the pathogenesis of myocarditis stems from animal models such as the coxsackievirus-induced myocarditis that causes both human and mouse myocarditis. And there lies our limitation.

Another very unique virus that affects the heart which we have very limited understanding of its pathogenesis is the human immunodeficiency virus (HIV). 

HIV is associated with multiple cardiac abnormalities including premature myocardial infarction, stroke, pericardial effusion, myocarditis, dilated cardiomyopathy, left ventricular dysfunction, infective endocarditis, and malignancy. The exact link is unclear and needs further study. Realizing this, in September 2012, the National Heart, Lung, and Blood Institute (NHLBI) AIDS working group stated that priority should be taken into recommendations and research involving HIV-related effects on the heart.

In my opinion, one the most promising area of research involves viral gene therapy. Using modified HIV viruses as gene vectors, they can be designed to cause reverse remodeling leading to myocardial recovery at the cellular and molecular level. The ability of the modified viruses to deliver therapeutic genes and alter cardiac myocyte biology leads to a reverse in progressive myocyte death. Learning from the advances made in the field of oncology, we can bring viral gene therapy to cardiology. 

The link between infectious disease and cardiology has always intrigued me. It started after I became an internal medicine specialist in Malaysia. I worked with a fantastic infectious disease consultant, Low Lee Lee, MD, who nurtured my interest in cardiology-related infectious diseases, namely in HIV and dengue related cardiac complications.

After my short stint in the infectious disease unit, I was sent to a hospital in Lahad Datu, Sabah in East Malaysia, prior to entering cardiology training, where most of the cases encountered were related to infectious diseases. These experiences enriched my clinical knowledge and made me more determined to pursue this field of research. 

After serving there for two years as an internal medicine specialist, I began to realize that there were very few research opportunities linking cardiac diseases with infections. Most of the trials were mainly in heart failure management and coronary artery disease focusing on primary and secondary prevention. Since these researchers were mainly from developed nations, I discovered the possibility of encountering tropical diseases endemic in this part of the world were rare. 

As a cardiologist working in Malaysia, I believe that with the right support and guidance I will have a huge pool of patients for future research. By improving our understanding of unique viral properties and its interaction with cardiac myocytes at the cellular and molecular level, we can develop novel therapies specific for each individual. This may well be the future of cardiology, and I am determined to get us there. 

Clinical Topics: Heart Failure and Cardiomyopathies

Keywords: Adenoviridae, Adenoviridae Infections, Coxsackievirus Infections, Enterovirus, Enterovirus Infections, Models, Animal, Myocarditis, Myocardium, Parvovirus

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