Thrombus Burden Greater in STEMI Patients With COVID-19

Patients with COVID-19 presenting to hospital with ST-segment elevation myocardial infarction have a higher burden of thrombus and may have poorer in-hospital outcomes than uninfected patients, according to a new series published last week.

In a study of 115 consecutive STEMI patients treated at a single high-volume center, those with COVID-19 had a higher incidence of multiple thrombotic culprit lesions and higher rate of stent thrombosis, as well as a higher modified thrombus grade after implantation of the first device and a lower resulting myocardial blush grade after intervention compared with uninfected STEMI patients.

“Consequently, these patients had lower ejection fractions and longer inpatient stays and were more likely to require an intensive care admission,” lead investigator Fizzah Choudry, MD, PhD (St Bartholomew’s Hospital, London, England), told TCTMD. Nonetheless, “the study also showed that we were able to deliver timely primary PCI in the COVID-19 era, to both COVID and non-COVID groups, despite the associated complexities we’ve all had to face. Early on, everyone was quite concerned we might have to think about thrombolysis because you’d never be able to deliver primary PCI, but we’ve managed do it, as have many, many other centers.”

The study, which was published July 14, 2020, in the Journal of the American College of Cardiology, is the first series looking exclusively at patients with type 1 myocardial infarction as opposed to ECG “mimics” that have been documented with COVID-19-positive patients, said Choudry. “We implemented COVID-19 testing in STEMI admissions quite early on in our experience, back in mid-March, because it allowed us to manage patients safely, and partly because we’d seen early anecdotal cases of symptomatic COVID-19 patients presenting with STEMI which were much more challenging to manage in the cath lab,” she said.

Like other hospitals around the world, they saw an approximate 30% reduction in primary PCI for STEMI and a 40% reduction in the activation of their heart attack center pathway during the height of the pandemic. 

In the series, the median age of STEMI patients admitted to Barts Heart Center between March 1 and May 20, 2020, was 62 years. The 39 patients with COVID-19 were more likely than non-COVID-19 patients to have diabetes, hypertension, and hyperlipidemia and to have had a prior PCI. They also presented with higher troponin, D-dimer, and C-reactive protein levels but had lower lymphocyte counts. Median door-to-balloon times were similar in both groups.

The study also showed that we were able to deliver timely primary PCI in the COVID-19 era. Fizzah Choudry

Multivessel thrombotic lesions were documented in 17.9% of COVID-19 patients but not in any of the STEMI patients without COVID-19. Similarly, stent thrombosis was observed in 10.3% of COVID-19-positive patients and 1.2% of non-COVID-19 patients (P = 0.04). Baseline TIMI 0/1 flow and thrombus grade 4/5 were similar between both patient groups, but the modified thrombus grade after first device was higher in those with COVID-19. Nearly 60% of COVID-19 patients received glycoprotein IIb/IIIa inhibitors versus 9.2% of non-COVID-19 patients (P < 0.0001), while aspiration thrombectomy was used in 17.9% of COVID-19 cases versus 1.3% of COVID-19-negative patients (P = 0.002). After the procedure, the median LVEF was lower in the COVID-19-positive patients (42.5% vs 45.0%; P = 0.019).

“From our results, I think we see can a clear signal toward higher thrombus burden in these STEMI patients with concurrent COVID-19,” said Choudry.

Higher thrombus burden in STEMI results in greater PCI complexity, she said, but there are also short-term implications. In the present study, admission length of stay and ICU admissions were significantly higher among patients with COVID-19 and a nonsignificant trend toward higher in-hospital mortality, the difference was not statistically significant compared with non-COVID-19 patients.

Regarding longer-term implications, Choudry pointed out that the COVID-19 patients with STEMI had multiterritorial infarcts, lower LVEFs, and higher peak plasma troponin levels than non-COVID-19 patients, and while these factors contributed to increased morbidity in the in-patient setting, additional follow-up is needed. “Luckily, we will be able to follow up with these patients,” she said.

As for why COVID-19 have a higher thrombus burden, researchers are still trying to get a handle on mechanisms. “We know that COVID-19 infection is associated with a systemic inflammatory response and a prothrombotic state,” said Choudry. “So the mechanisms of the results that we see, although it’s not clear, may be related to increased platelet activation, possibly endothelial dysfunction, or the direct effects of the virus on the immune system. We’re not certain, and we will need to study it more.”