"Complications included acute respiratory distress syndrome (12 [29%]), RNAaemia (six [15%]), acute cardiac injury (five [12%]) and secondary infection (four [10%]). 13 (32%) patients were admitted to an ICU and six (15%) died."
Believe it or not, this can happen infrequently with "ordinary" viruses: viral myocarditis (inflammation and infection of the heart muscle) is an under-appreciated killer of the young, with a mortality rate of between 25-50% [1] and is a well-known complication of, for example, influenza [2]. In fact, it's believed that myocarditis was involved in as much as 50% of Spanish flu fatalities in the early part of the 20th century. The difference is that if you're young and healthy, you're likely to clear infections well before they get to the point of systemically infecting each organ.
In the population of those who are acutely unwell with this novel virus, you have to remember that there is a massive selection bias for those hospital doctors to see the sickest people. Myocarditis is unfortunately one of those things that is therefore probably to some degree expected. The real question is "what is the probability that you end up in this terrible situation given you are infected with coronavirus" -- and in order to do that, you need a good estimate of how many people have been infected (but not died or seriously ill!) with the novel coronavirus. This is very hard to do in Wuhan, and estimates vary by orders of magnitude.
(from the article) 80% of people who died were over 60 years old and 75% had underlying health conditions including cardiovascular problems, so the fact that the virus caused fatal cardiovascular events in some of those cases is not unexpected.
About 80% of Americans over 60 have cardiovascular problems, compared to a third of elderly Chinese people. That stat indicates that fatality rates could be higher in the US (and other western countries, although I don't have those numbers immediately) than China.
https://www.thelancet.com/journals/lancet/article/PIIS0140-6...
"Complications included acute respiratory distress syndrome (12 [29%]), RNAaemia (six [15%]), acute cardiac injury (five [12%]) and secondary infection (four [10%]). 13 (32%) patients were admitted to an ICU and six (15%) died."