Bacteremia Following Complex Percutaneous Coronary Intervention

Bacteremic complications after cardiac catheterization and percutaneous coronary intervention are perhaps surprisingly rare considering the frequency of entry into the circulation of arterial sheaths, guide catheters, guidewires, balloon catheters, stents, atherectomy and thrombectomy devices, pressure wires and intravascular ultrasound catheters during complex coronary interventional procedures. Although septic endarteritis^1,2 and coronary stent infection^3,4 have been reported after percutaneous transluminal coronary angioplasty (PTCA), the incidence of bacteraemia after more complex procedures remains unclear but is still assumed to be infrequent and clinically unimportant. This current study investigates the frequency of bacteraemia after more complex percutaneous coronary intervention (PCI) which may have important implications for those patients who are at increased risk of infective endocarditis but require PCI. Patients and Methods Between April 2002 and March 2003, 147 consecutive patients undergoing PCI for single- and multi-vessel coronary artery disease were included in the study. All patients were apyrexial prior to PCI. Patient details are shown in Table 1: 38.8% had urgent/emergency PCI for acute coronary syndromes including acute myocardial infarction and 61.2% had elective PCI for stable angina pectoris. Procedures included balloon angioplasty, cutting balloon angioplasty, rotational coronary atherectomy and single and multiple stent implantation for complex coronary artery disease, bifurcation lesions, chronic total occlusions and saphenous vein graft disease (Table 2). Multiple lesions were addressed in 56.5% of patients and multiple vessel PCI performed in one-third of cases. Multiple devices were frequently used. All the procedures were performed via the femoral route. The skin was cleaned with an antiseptic alcoholic solution of 0.5% chlorhexidine prior to covering the patient with a sterile drape. Two operators performed the procedures. Standard preoperative scrubbing and sterile gowning of the operators was meticulously practiced, although masks and head covers were not used by the operators. At the end of the procedure, 1 set of blood cultures (aerobic and anaerobic bottles) was collected from the side arm of the arterial sheath using standard aseptic practice. The femoral arterial and venous sheaths were left in-situ for 12 hours, when a second set of blood cultures was collected prior to sheath removal. Four hourly temperatures were recorded after the procedure until discharge. Stastical Analysis Categorical variables are presented as percentages with associated 95% confidence limits. Continuous variables are presented as mean with 95% confidence limits. Univariate predictors of bacteraemia found in the first blood culture were sought using the Chi-squared test for categorical variables and the Wilcoxon rank sum test for continuous variables. Multivariate predictors of bacteraemia were sought using multivariate logistic regression. Variables with a p value of 37ºC– 38ºC, all had negative blood cultures. Only 1 patient required antibiotics. This patient with clinical evidence of respiratory infection had a micrococcus identified in 1 blood culture and Strep. pneumoniae grown in the sputum. Of the 26 patients with a positive first blood culture, only 3 had a temperature > 37ºC (37.2ºC, 37.4ºC and 37.5ºC) noted on 1 single recording. Of those with a positive second blood culture, only 4 had a temperature > 37ºC (37.2ºC, 37.2ºC, 37.5ºC and 37.8ºC). No patient developed clinical evidence of septicaemia, endarteritis or endocarditis in-hospital or after discharge. The univariate analysis of factors possibly associated with the incidence of bacteremia immediately after the PCI procedure is shown in Table 4. Only cigarette smoking achieved statistical significance in the multivariate analysis as shown in Table 5. The duration of the procedure and the number of devices introduced into the circulation did not appear to be associated with an increased incidence of bacteremia. Discussion Large retrospective studies of the frequency, risk factors and outcome for bacteremia after invasive cardiological procedures such as PTCA have reported an incidence of clinically important complications of between 0.11% and 0.64%.^2,5 These include septic endarteritis of the femoral or external iliac arteries and even mycotic aneurysm formation, septic thromboembolism, septic arthritis, endocarditis and epidural abscess^6–11 — often in association with Staph. aureus infection at the puncture site. After coronary stent implantation, infective endocarditis of the mitral valve and infective coronary artery aneurysm has been shown to complicate stent infection — a usually fatal complication.⁴ Although these studies did not set out to investigate the incidence of bacteremia, Samore et al.² reported a substudy of 150 patients who had blood cultures within the first week of PTCA. Eighteen percent had at least 1 positive blood culture for coagulase-negative staphylococcus, which was thought to represent self-limiting PTCA-related bacteremia. Shea et al. studied the frequency of bacteremia after PTCA from blood cultures taken from the femoral arterial sheath immediately and 30 minutes after the procedure in 164 patients.¹² Bacterial isolates were recovered in 8.0% of cultures with the coagulase-negative Staph. epidermidis being the most common (74%) microorganism isolated. Fever of > 38ºC was observed in 2.4% but thought to be “procedure-related” in only 1 case. In our current study, the incidence of bacteremia is significantly greater. We felt that this may be explained by the more complex nature of the PCI being performed in our study compared to the PTCA performed by Shea et al. with more devices being introduced into and out of the femoral artery sheath in order to treat multiple lesions in multiple vessels with additional guidewires, balloon catheters, other mechanical devices and stents. Only 12 patients (8.8%) had PTCA alone. However, the statistical analysis did not show a difference in the number of devices used in those with and in those without bacteremia. Immediately after completion of the procedure, almost 18% of cases had evidence of bacteremia. Overall, within the first 12 hours of having the femoral arterial sheath in-situ, 27.9% of patients had bacteria isolated from a blood culture. As Shea et al. showed, coagulase-negative staphylococcus is the most common microorganism responsible.¹² Although it is somewhat reassuring that there were no clinical sequelae as a result of the bacteremia — suggesting that routine antibiotic prophylaxis prior to PCI is not necessary, these findings may have important implications for patients who are at increased risk of infective endocarditis such as those with valvular heart disease, eg: mitral valve prolapse, or prosthetic valves who require PCI. We firmly believe that such patients should have prophylactic antibiotics prior to PCI, that extra care should be taken with aseptic technique and that the femoral artery sheaths should be removed early after the procedure in such cases. Moreover, this data would also support the routine removal of femoral artery sheaths early post-PCI, now that effective femoral artery closure devices are available. This may prevent the rare but serious complications associated with endarteritis of the femoral or iliac arteries that have been reported after PTCA. Endarteritis of the femoral artery puncture site where a closure device has also been used would be of particular concern. Finally, as complex procedures are becoming more commonplace as a result of an increase in the use of intracoronary ultrasound, pressure-wire assessment, thrombectomy and distal protection devices, and the increase in frequency of multilesion and multivessel PTCA and stenting following the introduction of drug-eluting stents, cardiologists and catheterization laboratory staff and catheterization laboratory designers should take all precautions possible to make such PCI procedures as sterile as possible. This should help to prevent the rare but lethal complication — coronary artery stent infection. Acknowledgement. We acknowledge the help and assistance of Dr. Godfrey Smith, Consultant Microbiologist, Department of Microbiology, Royal Liverpool Hospital, Liverpool, England, UK.

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