Study estimates and compares excess mortality due to cardiovascular diseases across multiple pandemic waves in the US

By Neha MathurReviewed by Danielle Ellis, B.Sc.Mar 3 2023

In a recent study published in Nature Cardiovascular Research, researchers estimated excess cardiovascular deaths in the United States of America (USA) between March 2020 and March 2022.

The study period spanned multiple coronavirus disease 2019 (COVID-19) waves when limited access to healthcare services for cardiovascular diseases (CVDs) increased actual cardiovascular deaths over expected deaths, as predicted by the negative binomial log-linear regression study model.

Background

Despite concerted efforts to provide medicare for non-COVID-19 patients, multiple waves of the pandemic severely impacted and limited access to cardiovascular healthcare in the United States, a phenomenon that requires in-depth evaluation. Furthermore, there is an urgent need to investigate the indirect effects of the COVID-19 pandemic on CVD patients over a longer duration, focusing on spatio-temporal variations in excess CVD-related deaths.

About the study

In the present study, researchers retrieved weekly death counts of the 50 US states between 2015 and 2022, which they used to identify CVD deaths per the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10). The team sourced data from the US-Centers for Disease Control and Prevention (CDC) department of the National Center for Health Statistics (NCHS). They analyzed data up to March 2022 only.

Further, the team measured the net difference between observed and expected death counts to compute excess CVD deaths. A fixed-effect negative binomial log-linear regression model projected the weekly death counts for the whole study period. Finally, the team disintegrated the time-varying pattern of death counts into temporal and seasonality components.

Results

There were 1,946,662 documented CVD deaths in the USA between 1 March 2020 and 26 March 2022. Strikingly, excess CVD deaths persisted throughout the two years of the COVID-19 pandemic in the USA. While their temporal trajectory nearly coincided with COVID-19-related deaths, their spatial distribution varied by region. Accordingly, excess CVD deaths declined in New Jersey and New York over time after attaining a peak during the first pandemic wave.

Since the COVID-19 pandemic has disrupted CVD medical care worldwide, the current study findings were consistent with several prior studies. Acute CVD conditions, such as ischemic heart disease (IHD) and hypertensive and cerebrovascular diseases, emerged as top reasons for excess CVD deaths. These conditions require emergent treatments; however, healthcare resources remained overtly burdened in managing COVID-19 cases during the pandemic, which diverted or hindered them from offering routine cardiovascular medical care. 

Another explanation for excess CVD deaths could be the reluctance of CVD patients to seek medication to avoid contracting COVID-19 in-hospital. A survey showed that cardiac diagnostic testing declined by 64% by April 2020 compared to the past year.

Multiple studies reported an increase in CDV deaths due to various reasons. ST-segment elevation myocardial infarction (STEMI) patients experienced a delay in treatment, with ~38% decrease in cardiac catheterization laboratory for STEMI activations in the USA. Compared to 2015–2019, in 2020, patients who underwent primary percutaneous coronary intervention took 11 to 13 minutes more of door-to-balloon time whether or not they had confirmed COVID-19.

The studies also documented a surge in in-hospital deaths among STEMI patients, 33% vs. 11% in STEMI patients with confirmed and suspected COVID-19. Also, the researchers noted that acute myocardial infarction caused 29% of total excess CVD deaths during the pandemic.

In response to it, professional cardiovascular associations commended several guidelines to reclaim cardiovascular care capacity back to normal. They introduced telemedicine to compensate for routine cardiovascular medicare. As a result, cardiac diagnostic test volumes surged back to almost pre-pandemic levels by April 2021.

While the in-hospital mortality rate declined markedly, STEMI care improved too, yet, there were excess CVD deaths during 2021–2022, indicating COVID-19 likely had a long-term effect on CVD patients. Also, as the pandemic is ongoing, with more severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants on the horizon, adverse impacts on CVD might re-emerge.

There is a vast possibility that COVID-19-induced lockdown increased physical inactivity, poor dietary habits, interrupted long-term disease management services, income loss, and the list goes on. Consequently, patients with chronic CVD might continue to experience quicker disease progression than normal. Studies showed that SARS-CoV-2 infection also heightened the risk of CVD-related deaths. 

Conclusions

Given COVID-19 hospitalization increased the risk of adverse CVD events by three times in four months from diagnosis, as assessed in a recent study, future studies must delineate the excess CVD deaths due to disrupted medicare systems and cardiac sequelae following SARS-CoV-2 infection.

Further study should clarify the mechanisms of the temporal–spatial pattern of excess CVD deaths in the USA. As COVID-19 continues to threaten public health, expanding healthcare resources and optimizing their capacity is a must to maintain cardiovascular care alongside other chronic diseases.