High incidence of post-discharge cardiovascular mortality after COVID-19 hospitalization: a data-linkage study in Southern Iran

The long-term cardiovascular sequelae of SARS-CoV-2 infection, a major component of Post-Acute COVID-19 Syndrome (PACS), is a global health challenge. However, detailed characterization of fatal cardiovascular outcomes following COVID-19 hospitalization, particularly from the Middle East, remains limited. We aimed to investigate the incidence and clinical characteristics of cardiovascular mortality among patients discharged after COVID-19-associated hospitalizations in southern Iran. We conducted a retrospective data-linkage study between regional death certificates (N = 25,425) and COVID-19 hospital discharge records (N = 51,346) from teaching hospitals affiliated with Shiraz University of Medical Sciences between March 2020 and March 2021. Cardiovascular death was defined using ICD-10 codes I00-I99 from official death certificates. A multivariable Cox regression analysis was performed on the cohort of cardiovascular deaths to identify factors associated with the time from discharge to death. The all-cause mortality rate following discharge from COVID-19 hospitalization was substantially high, comprising 18.54% (N = 4,715) of all regional deaths. A total of 845 post-discharge deaths (3.32% of all regional deaths) were classified as being due to cardiovascular causes. Notably, 71.4% of these patients had elevated troponin levels – indicating acute myocardial injury – during their index COVID-19 hospitalization, which constitutes 2.85% of mortality in discharged COVID-19 patients (1,331 out of 46,705). The median time from discharge to death was 18 days [IQR: 6, 49.5]. The most frequent underlying cardiovascular conditions were unspecified cardiovascular disease (13.4%) and acute myocardial infarction (9.3%). The on-arrival ECG showed a high prevalence of abnormalities, including QT dispersion ≥ 40ms (50.9%), poor R wave progression (44.8%), and ST segment depression (26.8%). Discharge with cardiovascular drugs was independently associated with a longer time to death (aHR: 0.759 [95% CI: 0.588, 0.981]). This study showed a significant burden of cardiovascular mortality during 6–9 months following discharge from COVID-19 hospitalization, associated with a high-risk in-hospital phenotype for rapid post-discharge cardiovascular mortality. These findings suggested the critical need for structured long-term cardiovascular monitoring and risk stratification for high-risk patients after COVID-19 hospitalization.