From:  Long-term cardiovascular sequelae of COVID-19 in patients with pre-existing heart failure: a systematic review

 Distribution and prevalence of proposed pathophysiological mechanisms for long-term cardiovascular sequelae in patients with pre-existing HF following COVID-19.

MechanismStudies reporting (n/32)Key quantitative exampleReferences
Direct myocardial injury28/32 (88%)Troponin elevation in 74% of patients at 3-month follow-up[7, 16, 17, 37, 50, 51, 6367]
Systemic inflammation25/32 (78%)IL-6 > 50 pg/mL associated with 2.1-fold increased risk of HF readmission at 12 months[7, 16, 55, 6871]
Endothelial dysfunction20/32 (63%)FMD < 5% in 68% of HFpEF vs. 42% of HFrEF patients at 6-month follow-up[6, 48, 49, 56, 69, 70, 72]
Autonomic dysregulation15/32 (47%)HRV SDNN < 50 ms in 61% of patients at 6-month follow-up[45, 47, 57, 68, 7275]

COVID-19: coronavirus disease 2019; FMD: flow-mediated dilation; HF: heart failure; HFpEF: heart failure with preserved ejection fraction; HFrEF: heart failure with reduced ejection fraction; HRV: heart rate variability; IL-6: interleukin-6; SDNN: standard deviation of normal-to-normal intervals.