Pre-existing CAD and risk of mortality
One of the most striking and statistically significant findings of our
cohort was the association between preexisting CAD and mortality.
Patients with CAD had 62% mortality compared to 22% for those without
prior CAD ((HR 2.4; 95% CI 1.16-4.9; P = 0.01) (figure 5). The
association between viral illness and cardiovascular morbidity and
mortality is well known. Previous work has shown much higher rates of
influenza related death among those patients with cardiovascular
disease. (13) Systemic illness puts significant stress on the heart as
it tries to meet increased metabolic demands. In our cohort, we found
several important differences between patients with preexisting CAD and
those without that could explain the high mortality seen in these
patients. Patients with preexistent CAD were significantly older (77 vs
61 years), had a higher prevalence of CKD (42 vs 14%) , underlying CHF
(26% vs 6%), EF<45% (42% vs 14%) and higher levels of pro
BNP and peak troponin T levels compared to those without CAD
(supplemental Table). Interestingly, the level of inflammatory markers
and D- dimer were not significantly different. While the exact mechanism
for worse outcomes in COVID-19 patients with preexisting CAD is unclear,
several theories have been suggested. Severe hypoxemia and cytokine
storm, mediated by an imbalanced response among subtypes of T helper
cells, may contribute to myocardial injury in COVID-19 patients and pose
a greater risk in patients with a history of CAD and heart failure (7,
9). SARS-CoV has also been shown to directly cause myocardial
inflammation via interaction with angiotensin-converting enzyme 2, a
known receptor for SARS-COV-2 expressed on myocytes and vascular
endothelial cells. (14, 15)