Small Study Highlights the Serious Nature of Coronary Stent Infections

WASHINGTON, DC—Coronary stent infections are highly fatal and represent an understudied complication following PCI, a new analysis highlights.

“Several important questions about coronary stent infections remain unanswered, thus necessitating larger studies,” said Nagendra Boopathy Senguttuvan, MD (Sri Ramachandra Institute of Higher Education and Research, Chennai, India), who presented his findings at CRT 2023. “Early recognition and appropriate treatment remain the tenets of successful management of coronary stent infections.”

Though the study potentially raises more questions than it answers, session moderator Davide Capodanno, MD, PhD (University of Catania, Italy), told TCTMD that it does a service by giving airtime to an issue that interventionalists don’t often think about. “Very few are aware of this complication, so at least they raise the awareness of the fact that this exists and maybe it can be prevented and treated,” he said.

Capodanno acknowledged that it’s hard to be able to differentiate a coronary stent infection from a general hospital-borne infection following PCI but said the treatment would be largely the same regardless. “One of the messages here is that for patients who really have infection of the stent, the lethality is quite high,” he said. “So it's very important and . . . probably a good call for more studies of this.”

The findings are slated to be published in Cardiovascular Revascularization Medicine.

Fatal Complication

For their analysis, Senguttuvan and colleagues included 79 cases of coronary stent infection (median age 57 years; 82% male; 55.7% DES) reported across 65 studies of complex PCI—defined as primary PCI; implantation of more than three stents in a single vessel; use of advanced plaque modification techniques like rotational ablation; or CTO, bifurcation, or left main stenting—conducted through November 2021. Definitions of coronary stent infection varied by study, but all were diagnosed clinically or based on imaging with or without microbiological evidence of infection.

Slightly more than one-third of patients (38%) presented with ACS, 72% had fever, and 62% had mycotic aneurysms. Additionally, 16% of patients were on dialysis, 16% had presence of vegetations, and 22% received femoral access. Staphylococcal species were the most prevalent type of infection (65%) followed by Pseudomonas (13%). The largest proportion of patients (43%) presented with infection between 0 and 7 days after PCI, but a full 19% didn’t present until after 6 months.

In total, 30.3% of patients with coronary stent infections died in the hospital (primary outcome). Those who had structural heart disease (P = 0.009) and NSTE ACS (P = 0.039) were more and less likely to die following coronary stent infection, respectively, and there was a trend toward worse survival with heart failure (P = 0.066).

Following PCI, if a patient develops fever, acute pericarditis, or ACS, Senguttuvan and colleagues propose a treatment algorithm for how to diagnose and treat potential coronary stent infections including blood cultures as well as echocardiography, PET, or angiography.

A major limitation of the study is that the researchers are not able to identify the incidence of coronary stent infection, Senguttuvan acknowledged.

Causality and Prophylactic Treatment?

As for why these infections are occurring, he said it’s also hard to know, but the inconsistency with which antibiotics are used following PCI doesn’t help. “There's no clear guidelines for antibiotics before coronary intervention,” he said, adding that without antibiotic treatment, an infection can turn into “a catastrophe.”

“So as a community, we have to maybe come up with clear guidelines of what kind of antibiotics should we administer to such patients prophylactically before coronary procedures,” Senguttuvan continued. “There is a severe paucity of data, [and without it] I’m just shooting in the dark.”

Prophylactic antibiotics aren’t necessarily needed for all PCI patients, he said, but some, including those undergoing longer procedures, “might be more prone to infection. We need to identify those patients.”

Commenting on the findings, Andrew Sharp, MD (University Hospital of Wales, Cardiff), wondered why there are so “few” cases of coronary stent infection. “I realize it's the venous system, but if you think about it, the frequency of pacemaker infections is very high. If you're not absolutely diligent when you're putting in a pacemaker, you're going to have infections every 2-3% of the cases that you do,” he pointed out.

However, millions of PCIs are performed every year, frequently in semi-sterile settings for emergent indications like primary PCIs and cardiac arrest, Sharp noted. “Yet, there’s a tiny amount of these reported cases. Do you think there's a lot more subclinical stuff going on or is there something protective about coronary flow that somehow keeps the stents clean?”

Senguttuvan guessed that a lot of these infections go unreported, if they are even diagnosed. "I know at least a handful of cardiologists who encounter the situation who have not published it,” he said, further emphasizing the potential importance of prophylactic antibiotics.

Moreover, he said, the rate of fatal anaphylaxis from widespread antibiotic administration would likely be lower than death from coronary infection.