He’s far from alone. How profound a toll Covid-19 has taken on heart health is only starting to emerge.

“We are seeing effects on the heart and the vascular system that really outnumber, unfortunately, effects on other organ systems,” says Dr Susan Cheng, a cardiologist at Cedars-Sinai Medical Centre in Los Angeles, California.

How anxiety and depression raise the risk of 29 physical health conditions

Among the unknowns: who’s most likely to experience these aftereffects? Are they reversible – or a warning sign of more heart disease later in life?

“We’re about to exit this pandemic as even a sicker nation” because of virus-related heart trouble, says Washington University’s Dr Ziyad Al-Aly, who helped sound the alarm about lingering health problems. The consequences, he adds, “will likely reverberate for generations”.

Heart disease has long been the top killer in the US and the world as a whole. In Hong Kong, heart disease is second to cancer as the top killer.

Cardiovascular symptoms are part of what’s known as long Covid, the catch-all term for dozens of health issues including fatigue and brain fog.

The US National Institutes of Health is beginning small studies of a few possible treatments for certain long Covid symptoms, including a heartbeat problem.

But Cheng says patients and doctors alike need to know that, sometimes, cardiovascular trouble is the first or main symptom of damage the coronavirus left behind.

Miracle of the human heart, and how to keep yours healthy

“These are individuals who wouldn’t necessarily come to their doctor and say, ‘I have long Covid,’” she says.

Camilleri first developed shortness of breath and later a string of heart-related and other symptoms after a late 2020 bout of Covid-19. He tried different treatments from multiple doctors to no avail, until winding up at Washington University’s long Covid clinic.

“Finally a turn in the right direction,” says the 43-year-old Camilleri.

There, he saw Dr Amanda Verma for worsening problems with his blood pressure and heart rate. Verma is part of a cardiology team that studied a small group of patients like Camilleri with perplexing heart symptoms, and found abnormalities in blood flow may be part of the problem.

How? Blood flow increases when people move around and subsides during rest. But some long Covid patients don’t get enough of a drop during rest because the fight-or-flight system that controls stress reactions stays activated, Verma says.

Some also have trouble with the lining of their small blood vessels not dilating and constricting properly to move blood through, she adds.

Hoping that helped explain some of Camilleri’s symptoms, Verma prescribed heart medicines that dilate blood vessels and others to dampen that fight-or-flight response.

Hughes, a physical therapist who works with long Covid patients, came up with a careful rehab plan after the treadmill test exposed erratic jumps in Camilleri’s heart rate.

“We’d see it worse if you were not on Dr Verma’s meds,” Hughes says, showing Camilleri exercises to do while lying down and monitoring his heart rate. “We need to rewire your system” to normalise that fight-or-flight response.

Camilleri noticed some improvement as Verma mixed and matched prescriptions based on his reactions. But then a second bout with Covid-19 in the spring caused even more health problems, a disability that forced him to retire.

How big is the post-Covid heart risk? To find out, Al-Aly analysed medical records from a massive US Veterans Administration database.

People who’d survived Covid-19 early in the pandemic were more likely to experience abnormal heartbeats, blood clots, chest pain and palpitations, even heart attacks and strokes up to a year later compared to the uninfected. That includes even middle-aged people without prior signs of heart disease.

Al-Aly estimated four of every 100 people need care for some kind of heart-related symptom in the year after recovering from Covid-19.

Per person, that’s a small risk. But he says the pandemic’s sheer enormity means it added up to millions left with at least some cardiovascular symptoms.

While a reinfection might still cause trouble, Al-Aly’s now studying whether that overall risk dropped thanks to vaccination and milder coronavirus strains. More recent research confirms the need to better understand and address these cardiac aftershocks.

An analysis earlier this year of a large US insurance database found long Covid patients were about twice as likely to seek care for cardiovascular problems including blood clots, abnormal heartbeats or stroke in the year after infection, compared to similar patients who’d avoided Covid-19.

A post-infection link to heart damage isn’t that surprising, Verma notes. She pointed to rheumatic fever, an inflammatory reaction to untreated strep throat – especially before antibiotics were common – that scars the heart’s valves.

“Is this going to become the next rheumatic heart disease? We don’t know,” she says.

But Al-Aly says there’s a simple take-home message: you can’t change your history of Covid-19 infections but if you’ve ignored other heart risks – like high cholesterol or blood pressure, poorly controlled diabetes or smoking – now’s the time to change that.

“These are the ones we can do something about. And I think they’re more important now than they were in 2019,” he says.