COVID-19 causes endotheliitis (inflammation of the blood vessel lining), which triggers a hypercoagulable state. This can lead to small or large blood clots , resulting in heart attacks or strokes even in young, healthy patients. The Long Aftershock: "Mr. Validity" and Post-COVID Life

The virus uses the ACE2 receptor as a "lock" to enter cells; because the heart is rich in these receptors, the virus can directly invade and cause myocarditis (inflammation of the heart muscle).

The story often continues long after the fever breaks. Recent studies, such as the Mount Sinai PET/MRI study , show that 57% of "recovered" patients with lingering symptoms had evidence of persistent heart or lung inflammation up to a year later. COVID-19's consequences for the heart - Harvard Gazette

The story of COVID-19's impact on the heart is a tale of two phases: an acute "stress test" followed by a potentially long "aftershock". While primarily known for attacking the lungs, the virus frequently targets the cardiovascular system, leading doctors to redefine it as a in its own right. The Acute Crisis: "The Great Stress Test"

An overactive immune response releases massive amounts of inflammatory proteins (cytokines) that can damage heart tissue and lead to acute heart failure .