Study findings updated . AI-assisted evidence summary, not individual medical advice or a clinician endorsement.
THE SHORT VERSION
What’s worth knowing.
The key findings, what they mean, and the context that matters.
THE HEADLINE TAKEAWAYNearly 1 in 2seniors hospitalized with COVID who died or had a heart or clot event within a year
Seniors hospitalized with COVID fared worse within a year than flu patients.
Among more than a million Medicare patients (average age 79), 48.8% of those hospitalized with COVID in the Omicron era died or were hospitalized again for a heart attack, stroke, blood clot, heart failure or cardiac arrest within a year. After a flu hospitalization, the figure was 33.4%. Compared with earlier COVID waves, deaths fell, but heart attacks, strokes, clots and heart failure rose.
Omicron is often called mild. But for older adults sick enough to be hospitalized, the following year brought a heavy load of heart and clot problems. Heart-protective follow-up after discharge matters. This was an observational study of Medicare records, so it shows links, not proof that COVID itself caused the extra heart events.
See the evidence
A retrospective study of over a million older US Medicare patients hospitalized for COVID or flu, each followed for one year.
From the study: “The risk of the primary outcome in the Omicron cohort was lower than in the pre-Omicron cohort (48.8% versus 49.3%; standardized risk difference, -0.6% [95% CI, -0.8% to -0.3%]) but higher than in the influenza cohort (48.8% versus 33.4%; risk difference, 15.4% [15.1%-15.6%]).”
Nearly 1 in 2
Decker, Sérgio R R et al.. Long-term Cardiovascular Outcomes in US Medicare Beneficiaries After COVID-19 Hospitalization During the Omicron Era.. Circulation. Population health and outcomes. 2026.
From the study: “We included 1 184 182 patients (mean age 79 years; 51% women):361 382 in the Omicron cohort, 731 455 in the pre-Omicron cohort, and 91 345 in the influenza cohort.”
Nearly 1 in 2
Decker, Sérgio R R et al.. Long-term Cardiovascular Outcomes in US Medicare Beneficiaries After COVID-19 Hospitalization During the Omicron Era.. Circulation. Population health and outcomes. 2026.
From the study: “The primary outcome was a composite of all-cause death and hospitalization for myocardial infarction, ischemic stroke, transient ischemic attack, pulmonary embolism, deep vein thrombosis, heart failure, and cardiac arrest within 1 year of the index admission.”
Nearly 1 in 2
Decker, Sérgio R R et al.. Long-term Cardiovascular Outcomes in US Medicare Beneficiaries After COVID-19 Hospitalization During the Omicron Era.. Circulation. Population health and outcomes. 2026.
COVID survivors faced higher heart risks for a year, even without hospitalization.
1.7× AFib hazardhazard ratio for new atrial fibrillation, COVID survivors vs. uninfected veterans
US veterans who survived the first month of COVID were compared with millions of uninfected veterans. Over the next year they had more new strokes, rhythm problems, heart inflammation, heart failure and clots. For atrial fibrillation, an irregular heartbeat, the hazard ratio was 1.71: 10.74 extra cases per 1,000 people at 12 months. Risk was raised even in people never hospitalized.
Most people with COVID are never hospitalized. Extra heart problems turning up months later, even after illness managed at home, mean new palpitations, chest pain or breathlessness after COVID deserve a check. Participants were US veterans infected early in the pandemic, largely before vaccines, and the observational design shows links, not proof of cause.
See the evidence
An observational study of US Veterans Affairs health records comparing 153,760 COVID survivors with two large uninfected control groups over about a year.
From the study: “There were increased risks of atrial fibrillation (HR = 1.71 (1.64, 1.79); burden 10.74 (9.61, 11.91))”
1.7× AFib hazard
Xie Y et al. Long-term cardiovascular outcomes of COVID-19. Nature medicine. 2022.
From the study: “These risks and burdens were evident even among individuals who were not hospitalized during the acute phase of the infection and increased in a graded fashion according to the care setting during the acute phase (non-hospitalized, hospitalized and admitted to intensive care).”
1.7× AFib hazard
Xie Y et al. Long-term cardiovascular outcomes of COVID-19. Nature medicine. 2022.
Pandemic years wiped out almost a decade of US heart-health progress.
228,524 extra deathsmore US cardiovascular deaths than expected from 2020 to 2022
Among US adults 35 and older, death rates from heart disease and stroke fell 8.9% from 2010 to 2019. They then rose 9.3% from 2019 to 2022, landing near the 2010 level. From 2020 to 2022, 228,524 more cardiovascular deaths occurred than pre-pandemic trends predicted, 9% more than expected.
Years of steady progress against America's leading killer reversed during the pandemic and had not recovered by 2022. Catching up on checkups and control of blood pressure and cholesterol is urgent. Death records show what happened, not why; the study cannot separate infection's direct effects from delayed care, stress or other pandemic disruptions.
See the evidence
An analysis of US national death records for adults 35 and older from 2010 to 2022, comparing actual cardiovascular deaths with pre-pandemic trends.
From the study: “The national CVD AAMR declined by 8.9% from 2010 to 2019 (456.6-416.0 per 100,000) and then increased by 9.3% from 2019 to 2022 to 454.5 per 100,000, which approximated the 2010 rate (456.7 per 100,000).”
228,524 extra deaths
Woodruff RC et al. Trends in Cardiovascular Disease Mortality Rates and Excess Deaths, 2010-2022. American journal of preventive medicine. 2024.
From the study: “Using national mortality data from the National Vital Statistics System, deaths among adults aged ≥35 years were classified by underlying cause of death International Classification of Diseases 10th Revision codes for CVD (I00-I99), heart disease (I00-I09, I11, I13, I20-I51), and stroke (I60-I69).”
228,524 extra deaths
Woodruff RC et al. Trends in Cardiovascular Disease Mortality Rates and Excess Deaths, 2010-2022. American journal of preventive medicine. 2024.
Catching COVID again was linked to more heart problems than one infection.
Reinfection: 3.0×hazard ratio for new heart and vessel disorders, reinfected vs. infected once
Among US veterans, people who caught COVID two or more times were compared with those infected only once. In the 6 months after reinfection, the hazard ratio for new cardiovascular (heart and blood vessel) disorders was 3.02, which works out to 62.80 extra cases per 1,000 people. The added risk appeared whether or not people had been vaccinated.
Many Americans have now had COVID more than once. A previous infection or vaccination did not erase the heart toll of another bout, so avoiding repeat infections still matters. The veterans were mostly white men, and people who get reinfected may differ in ways health records miss, so this shows a link, not proof.
See the evidence
An observational study of US Veterans Affairs records comparing 40,947 reinfected people with 443,588 infected once and millions never infected.
From the study: “Compared to those with no reinfection, those who had reinfection exhibited increased risk of sequelae in the pulmonary (HR = 3.54, 95% CI = 3.29–3.82; burden = 75.74, 95% CI = 68.47–83.50) and several extrapulmonary organ systems including cardiovascular disorders (HR = 3.02, 95% CI = 2.80–3.26; burden = 62.80, 95% CI = 56.17–69.91)”
Reinfection: 3.0×
Bowe B et al. Acute and postacute sequelae associated with SARS-CoV-2 reinfection. Nature medicine. 2022.
Vaccinated people had far fewer heart failure and clot complications after COVID.
0.2× clot hazardhazard ratio, vein clots in month after infection: vaccinated vs. not
Researchers compared 10.17 million vaccinated and 10.39 million unvaccinated adults in the UK, Spain and Estonia. In the month after catching COVID, vaccinated people had a hazard ratio of 0.22 for vein clots, 0.53 for artery clots such as heart attack and stroke, and 0.45 for heart failure (below 1 means lower risk). The gap narrowed but held 91-180 days after infection.
Worry about rare vaccine side effects can overshadow this: vaccination was linked to fewer of the clots and heart failure that COVID itself brings, likely by making infections milder. This was observational, from the early vaccine rollout in Europe, so unmeasured differences between vaccinated and unvaccinated people could remain.
See the evidence
A multinational cohort study using routine health records from the UK, Spain and Estonia during the early vaccine rollout, tracking complications for a year after any infection.
From the study: “Vaccination was associated with reduced risks of acute (30-day) and post-acute COVID-19 VTE, ATE and HF: for example, meta-analytic sHR of 0.22 (95% CI 0.17 to 0.29), 0.53 (0.44 to 0.63) and 0.45 (0.38 to 0.53), respectively, for 0-30 days after SARS-CoV-2 infection, while in the 91-180 days sHR were 0.53 (0.40 to 0.70), 0.72 (0.58 to 0.88) and 0.61 (0.51 to 0.73), respectively.”
0.2× clot hazard
Mercadé-Besora N et al. The role of COVID-19 vaccines in preventing post-COVID-19 thromboembolic and cardiovascular complications. Heart (British Cardiac Society). 2024.
From the study: “The study included 10.17 million vaccinated and 10.39 million unvaccinated people.”
0.2× clot hazard
Mercadé-Besora N et al. The role of COVID-19 vaccines in preventing post-COVID-19 thromboembolic and cardiovascular complications. Heart (British Cardiac Society). 2024.
From the study: “We used two composite outcomes: (1) VTE, as an aggregate of PE and DVT and (2) ATE, as a composite of IS, TIA and MI.”
0.2× clot hazard
Mercadé-Besora N et al. The role of COVID-19 vaccines in preventing post-COVID-19 thromboembolic and cardiovascular complications. Heart (British Cardiac Society). 2024.
COVID infection carried more myocarditis risk than vaccines, with one exception.
97 vs 16 per millionextra myocarditis cases per million men under 40: second Moderna dose vs. infection
Myocarditis, inflammation of the heart muscle, was rare among tens of millions of vaccinated people in England. In the 28 days after a Pfizer dose, it occurred 1.52 to 1.72 times the usual rate (an incidence rate ratio), versus 11.14 after a positive test before vaccination. But in men under 40, a second Moderna dose was linked to 97 extra cases per million, versus 16 after infection.
For most people, catching COVID posed a bigger myocarditis threat than vaccination. For young men, the vaccine type mattered, a nuance worth raising with a doctor. Based on hospital records during England's first vaccine rollout; it shows links, not proof, and vaccines and advice have since changed.
See the evidence
A self-controlled case series, comparing each person's risk after a shot or infection with their own baseline, covering tens of millions of vaccinated people in England.
From the study: “Risk of myocarditis was increased in the 1 to 28 days after a first dose of ChAdOx1 (incidence rate ratio, 1.33 [95% CI, 1.09-1.62]) and a first, second, and booster dose of BNT162b2 (1.52 [95% CI, 1.24-1.85]; 1.57 [95% CI, 1.28-1.92], and 1.72 [95% CI, 1.33-2.22], respectively) but was lower than the risks after a positive SARS-CoV-2 test before or after vaccination (11.14 [95% CI, 8.64-14.36] and 5.97 [95% CI, 4.54-7.87], respectively).”
97 vs 16 per million
Patone M et al. Risk of Myocarditis After Sequential Doses of COVID-19 Vaccine and SARS-CoV-2 Infection by Age and Sex. Circulation. 2022.
From the study: “In men younger than 40 years old, the number of excess myocarditis events per million people was higher after a second dose of mRNA-1273 than after a positive SARS-CoV-2 test (97 [95% CI, 91-99] versus 16 [95% CI, 12-18]).”
97 vs 16 per million
Patone M et al. Risk of Myocarditis After Sequential Doses of COVID-19 Vaccine and SARS-CoV-2 Infection by Age and Sex. Circulation. 2022.
Long COVID, even after mild illness, was tied to new heart disease.
18.2% vs 8.4%women with long COVID vs. without who had a new heart or vessel event
In Stockholm, working-age adults diagnosed with long COVID, never hospitalized for COVID and without prior heart disease, were compared with peers without it. During follow-up, 18.2% of women and 20.6% of men with long COVID had a new heart or vessel event, versus 8.4% and 11.1% without. Adjusted hazard ratios were 2.06 for women and 1.33 for men, and 3.11 for irregular rhythms in women.
Most long COVID patients were never hospitalized, and most here were women. Their heart health, especially heart rhythm, may deserve routine checks, not just attention to fatigue. This Swedish registry study is observational, and people with long COVID see doctors more often, so some extra heart diagnoses may reflect closer checking.
See the evidence
A population registry study of 1,217,693 working-age adults in Stockholm, 8999 of them diagnosed with long COVID, followed for several years.
From the study: “Cumulative incidence of any cardiovascular event was higher in long COVID group (women 18.2%, men 20.6%) compared with control group (women 8.4%, men 11.1%).”
18.2% vs 8.4%
Lindberg P et al. Long COVID and risk of incident cardiovascular disease: a prospective cohort study using the Multimorbidity Integrated Registry Across Care Levels in Stockholm (MIRACLE-S) cohort. EClinicalMedicine. 2026.
From the study: “In a fully adjusted model, long COVID was associated with the composite cardiovascular outcome (women HR 2.06, 95% CI 1.92-2.22; men HR 1.33, 1.20-1.48), cardiac arrhythmia (women HR 3.11, 2.85-3.39; men HR 1.61, 1.41-1.85), and coronary artery disease (women HR 1.25, 1.04-1.52; men HR 1.26, 1.05-1.51).”
18.2% vs 8.4%
Lindberg P et al. Long COVID and risk of incident cardiovascular disease: a prospective cohort study using the Multimorbidity Integrated Registry Across Care Levels in Stockholm (MIRACLE-S) cohort. EClinicalMedicine. 2026.
From the study: “Among 1,217,693 individuals, 8999 (0.7%) had long COVID diagnosis (66% women).”
18.2% vs 8.4%
Lindberg P et al. Long COVID and risk of incident cardiovascular disease: a prospective cohort study using the Multimorbidity Integrated Registry Across Care Levels in Stockholm (MIRACLE-S) cohort. EClinicalMedicine. 2026.
Mostly mild Omicron infections were not linked to more heart complications.
No overall risein new heart complications after mostly mild Omicron infections in Singapore
In Singapore's early Omicron wave, people who tested positive, 97.5% with mild illness, were compared with people who tested negative. Over the following months, infection was not linked to more new heart or vessel complications overall (hazard ratio 1.01), apart from a small rise in irregular heart rhythms. Risk was concentrated in those hospitalized (hazard ratio 2.81) or severely ill (5.52).
It offers some reassurance: for most people with a mild Omicron infection, heart risks may be far smaller than early-pandemic studies suggested. Severe illness remains the danger zone. An observational study in a multi-ethnic Asian population with under a year of follow-up, so later or rarer heart problems may be missed.
See the evidence
A national cohort study in Singapore comparing people who tested positive or negative for COVID during the early Omicron wave, using testing and insurance claims data.
From the study: “The majority (97.5%, 366 593/375 903) of infected individuals had mild infection not requiring hospitalization.”
No overall rise
Wee LE et al. Long-term cardiovascular, cerebrovascular, and thrombotic complications after SARS-CoV-2-Omicron infection: a retrospective cohort study. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. 2024.
From the study: “There was no overall increased risk of new-incident cardiovascular complications, (adjusted hazards ratio, aHR = 1.01 [0.97-1.07]) amongst COVID-19 survivors when compared against test-negatives.”
No overall rise
Wee LE et al. Long-term cardiovascular, cerebrovascular, and thrombotic complications after SARS-CoV-2-Omicron infection: a retrospective cohort study. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. 2024.
From the study: “Risk and burdens of new-incident cardiovascular complications predominantly accrued in hospitalized (aHR = 2.81 [2.26-3.50]) and severe COVID-19 cases (aHR = 5.52 [3.76-8.10]).”
No overall rise
Wee LE et al. Long-term cardiovascular, cerebrovascular, and thrombotic complications after SARS-CoV-2-Omicron infection: a retrospective cohort study. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. 2024.
The main analysis found no clear difference in the heart-pumping measure
The trial measured changes in the share of blood pumped out by the heart’s main chamber. Over 16 weeks, the main analysis found no clear difference between losartan plus prednisolone and placebo.
The randomized trial involved post-COVID syndrome and heart inflammation. The main uncertainty range included no difference. A supporting analysis allowed for starting values and reported a positive difference in this pumping measure. Its comparison group is not named here; it does not override the main result.
Study details & original results
Puntmann, Valentina O et al.. Losartan and prednisolone for post-COVID syndrome and cardiac inflammation: a randomized, double-blind, placebo-controlled trial.. Nature communications. 2026.
Change in LV ejection fraction after 16 weeks of losartan plus prednisolone versus placebo; neutral in the primary unpaired t-test analysis.
The Omicron result depended on what was counted and compared
At one year, fewer patients had died after Omicron-era than earlier COVID-19 hospitalization. Death or a heart, circulation or blood-clot hospital stay was more common than after historical flu hospitalization.
These Medicare patients were at least 65 years old. The two comparisons count different outcomes and use different groups. They do not show that every heart or circulation risk improved, or that Omicron and flu had equal outcomes.
Study details & original results
Decker, Sérgio R R et al.. Long-term Cardiovascular Outcomes in US Medicare Beneficiaries After COVID-19 Hospitalization During the Omicron Era.. Circulation. Population health and outcomes. 2026.
One-year composite of all-cause death and hospitalization for cardiovascular or thromboembolic events among Medicare beneficiaries aged at least 65 years hospitalized with Omicron-era COVID-19 versus a historical influenza hospitalization cohort.
48.8% vs 33.4%; risk difference 15.4% 15.1%-15.6%
One-year all-cause mortality among Medicare beneficiaries aged at least 65 years hospitalized with Omicron-era versus pre-Omicron COVID-19.
34.2% vs 39.7%; risk difference -5.5% -5.7% to -5.3%
Dates show when findings were added here, not when papers were published. Study populations and comparisons differ.
WHEN YOU WANT TO GO DEEPERSee all 4 findingsOriginal results, comparisons and study details.
2 of 2 source groupsFindings stay together with their study.
SOURCE 032 findings
Puntmann, Valentina O et al.. Losartan and prednisolone for post-COVID syndrome and cardiac inflammation: a randomized, double-blind, placebo-controlled trial.. Nature communications. 2026.
Decker, Sérgio R R et al.. Long-term Cardiovascular Outcomes in US Medicare Beneficiaries After COVID-19 Hospitalization During the Omicron Era.. Circulation. Population health and outcomes. 2026.
One-year composite of all-cause death and hospitalization for cardiovascular or thromboembolic events among Medicare beneficiaries aged at least 65 years hospitalized with Omicron-era COVID-19 versus a historical influenza hospitalization cohort.
Added
48.8% vs 33.4%; risk difference 15.4%15.1%-15.6%Source [2]
One-year all-cause mortality among Medicare beneficiaries aged at least 65 years hospitalized with Omicron-era versus pre-Omicron COVID-19.
Added
34.2% vs 39.7%; risk difference -5.5%-5.7% to -5.3%Source [2]
Browse the 11 original sourcesThe complete bibliography behind this monitor.
[1]
Meyahnwi, Didien et al.. Short- and Long-Term Prognosis of COVID-19-Associated Versus Non-COVID-19 Takotsubo Cardiomyopathy: A Propensity-Matched Nationwide Study.. Cureus. 2026.
Decker, Sérgio R R et al.. Long-term Cardiovascular Outcomes in US Medicare Beneficiaries After COVID-19 Hospitalization During the Omicron Era.. Circulation. Population health and outcomes. 2026.
Puntmann, Valentina O et al.. Losartan and prednisolone for post-COVID syndrome and cardiac inflammation: a randomized, double-blind, placebo-controlled trial.. Nature communications. 2026.
Floridia, Marco et al.. New Cardiovascular Diagnoses, Symptoms and Functional Status Following SARS-CoV-2 Infection in a National Cohort of 1,734 Patients in Italy.. Heart, lung & circulation. 2026.
Mercadé-Besora N et al. The role of COVID-19 vaccines in preventing post-COVID-19 thromboembolic and cardiovascular complications. Heart (British Cardiac Society). 2024.
Lindberg P et al. Long COVID and risk of incident cardiovascular disease: a prospective cohort study using the Multimorbidity Integrated Registry Across Care Levels in Stockholm (MIRACLE-S) cohort. EClinicalMedicine. 2026.
Wee LE et al. Long-term cardiovascular, cerebrovascular, and thrombotic complications after SARS-CoV-2-Omicron infection: a retrospective cohort study. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. 2024.
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