2.1.1  Role of underling CV comorbidities
The patients with pre-existing CVD appear to have heightened vulnerability to develop COVID-19 and tend to have more severe disease with worse clinical outcomes [1,4,6,8]. Various CV risk factors also adversely affect porgnosis of these patients, although they do not seem to increase likleihood of developing the infection. A meta-analysis of six published studies from China including 1527 patients with COVID-19 reported 9.7%, 16.4% and 17.1% prevalence of diabetes, cardio-cerebrovascular disease and hypertension respectively [4]. Although the prevalence of diabetes and hypertension in this cohort was same as in the Chinese general population, the prevalence of cardio-cerebrovascular disease was considerably higher. More importantly, the presence of diabetes, cardio-cerebrovascular disease and hypertension was associated with a 2-fold, 3-fold and 2-fold greater risk of severe disease or requiring intensive care unit (ICU) admission, suggesting prognostic impact of these comorbidities. A much larger report from the Chinese Center for Disease Control and Prevention described clinical outcomes in 44672 confirmed cases of COVID-19 [1]. The overall case fatality rate (CFR) was 2.3% in the entire cohort but significantly higher (6%, 7.3% and 10.5% respectively) in patients with hypertension, diabetes and CVD.
Although data is lacking, the prevalence of various CV comorbidities and their impact on clinical outcomes seem to vary considerably across different geographic locations. The CFRs have been lower in China outside Hubei province and many other countries but much higher in some European nations [2]. A small report including 21 patients from Washington, United States of America presented a particularly grim scenario [9]. Comorbidities were common in this cohort, with diabetes present in 33.3% and congestive heart failure in 42.9%. Acute cardiac dysfunction occurred in 33.3% patients and 52.4% patients died. However, the overall CFR in the United States seems to be much lower (201 deaths out of 15219 confirmed cases) [2], although it is likely to rise as many of the patients are currently hospitalized and have not yet had the definite outcome.