Background. No previous study has analyzed the possible responsibility of fellows-in-training in terms of the risk of complications during cardiac catheterization. Thus, we sought to identify possible risk factors for access site complications following cardiac catheterization procedures, with particular attention to the role of cardiology fellows. Methods. A total of 1,288 left heart catheterization procedures (both diagnostic and interventional), performed over a 1-year period at a university hospital, were retrospectively evaluated to determine the incidence of local complications (pseudoaneurysm, arterio-venous fistula, major hematoma or bleeding, vascular dissection). Several clinical (age, gender, previous coronary artery bypass surgery, indication to the exam) and procedural (procedure performed by the fellow, access site, type of procedure, urgent setting, use of glycoprotein IIb/IIIa inhibitors, simultaneous right heart catheterization, use of closure devices) covariables were considered. Major adverse cardiovascular and cerebrovascular events (MACCE: death, myocardial infarction, cerebrovascular event) were also assessed. Results. The overall access site complication rate was 2.6%. On multivariate regression analysis, the only two predictors of local complications were female gender (odds ratio [OR] 3.2, 95% confidence interval [CI] 1.6–6.5) and femoral approach (OR 3.9, 95% CI 1.2–12.1). The rate of MACCE was 1.2%, mainly after percutaneous coronary interventions, with only 1 death overall (0.07%). Procedures performed by cardiology fellows were not associated with an increased incidence of either complication. Conclusions. Cardiology fellows can safely perform cardiac catheterization procedures without an increase in the rate of local and major cardiovascular complications. Of course, the presence and watchful supervision of an attending physician is still essential to ensure both patient safety and optimal training.

       Percutaneous left heart catheterization, including pressure measurements, left ventriculography, coronary angiography and percutaneous coronary interventions (PCI), is nowadays considered the gold standard for the diagnosis, evaluation and treatment of several cardiac diseases (coronary artery disease [CAD], valvular and congenital heart diseases, cardiomyopathies, status post-heart transplant).¹ Although it has shown major benefits, left heart catheterization is not free of complications, as it is an invasive procedure.² The most frequently observed complications are related to access site.³ Such complications, albeit rarely life-threatening, may require additional treatment, including further compression or thrombin injection (for pseudoaneurysms), blood transfusions or vascular surgery. Access site complications may also expose patients to further discomfort, a longer hospital stay and higher hospital costs.^4,5 Several observational studies and some subanalyses from randomized trials evaluated the possible risk factors for local vascular complications and showed that established predictors are older age, female gender, body surface area, peripheral vascular disease, some antithrombotic regimens and access site.^3,6–13
       Despite this large body of evidence, no study has addressed the role of cardiology fellows in the incidence of local vascular complications. We therefore examined our institution’s recent data on a wide range of patients who underwent left heart catheterization (both diagnostic and interventional) in a university setting in order to identify risk factors for vascular complications, with particular attention to the possible responsibility of cardiology fellows.

Methods
       We collected data from all percutaneous procedures performed in the catheterization laboratory at our institution from January 1, 2003 to December 31, 2003. We included all procedures in which left heart catheterization was performed, with or without right heart catheterization. We excluded all right heart catheterization-only procedures, the two procedures performed via the brachial artery approach (no local complications occurred after these procedures), and the procedures in which an intra-aortic balloon pump was placed (because it was indicated primarily for prophylaxis prior to cardiac surgery and its removal was thus by means of surgical suture). Written informed consent was obtained from each patient. All procedures were performed using 6-French sheaths. The radial artery approach was electively performed by one senior cardiologist and only occasionally by the others, while cardiology fellows did not perform any transradial procedures. Weight-adjusted heparin (70 U/Kg) was administered in all the transradial diagnostic and interventional procedures, and only in the interventional procedures performed via the femoral artery approach. The interventional portion of the procedure was always performed by a senior cardiologist, regardless of whether a fellow performed the preceding angiogram (thus obtaining the arterial access). The radial sheath was always removed immediately after all the procedures. Femoral closure was achieved using a closure device (Angio-Seal™, St. Jude Medical, St. Paul, Minnesota) or by manual compression. The closure device was always deployed by a senior cardiologist, while manual compression was always performed by a trained fellow. In the latter case, the sheath was immediately removed after diagnostic procedures, whereas after interventional procedures, it was removed when the activated clotting time was < 180 seconds. After Angio-Seal deployment, patients were kept in bed for 4 hours; after manual compression, they were kept in bed until the following morning.
       Definition of the primary endpoint. Data concerning complications after cardiac catheterization were prospectively collected until patient discharge (or in-hospital death). When an event occurred, a detailed report was completed by the physician taking care of the patient. Percutaneous access site complications were defined as the occurrence of: 1) pseudoaneurysm or arterio-venous (A-V) fistula, both documented by an ultrasound examination; 2) major hematoma or major bleeding, both requiring blood transfusion, vascular surgery or prolongation of hospital stay according to the physician taking care of the patient; and 3) relevant intraluminal iatrogenic dissection of access arteries. All patients were examined the day following the procedure. The patient’s access site was carefully inspected and palpated. The groin site was auscultated, and ultrasound examination was performed if clinically indicated.
       Predictors of access site complication. In order to identify clinical and procedural characteristics associated with an access site complication, we retrospectively collected details on several variables possibly influencing the occurrence of adverse events. The variables analyzed were: 1) age; 2) sex; 3) radial or femoral access site; 4) diagnostic or interventional procedure; 5) contemporary performance of right heart catheterization; 6) clinical indication for the procedure: coronary artery disease or other; 7) urgent (cardiogenic shock, acute myocardial infarction or unstable angina with recurrent symptoms) or elective setting; 8) utilization of glycoprotein (GP) IIb/IIIa inhibitors; 9) previous coronary artery bypass graft (CABG) surgery; 10) use of the Angio-Seal closure device; 11) percutaneous femoral artery puncture performed by the cardiology fellow (who performed the procedure under the watchful observation of an attending physician). Fellows were pre-instructed with a series of lectures and theoretical self-study at the beginning of their invasive cardiology training. They were then progressively allowed hands-on involvement in the daily caseload of the catheterization laboratory.
       Secondary endpoints. We further evaluated the incidence of major adverse cardiovascular and cerebrovascular events (MACCE), defined as death, myocardial infarction, CABG due to coronary dissection and cerebrovascular event (CVE). In particular, myocardial infarction was defined as the occurrence of ischemic chest pain associated with an elevation of serum creatine kinase-myocardial band (CK-MB) > 3 times the upper limit of normal. A CVE was defined as the onset of a new neurological deficit that occurred after the procedure, anytime during the index hospitalization.
       Statistical analysis. Continuous variables are expressed as mean ± standard deviation. Comparisons between groups were performed using the Student’s t-test. Categorical variables are expressed as percentages and were compared using the Fisher’s exact test. Forward, stepwise multivariate logistic regression analysis was performed to identify independent predictors of access site complications. The adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated for each statistically significant variable. A p-value < 0.05 was considered statistically significant.

Results
       Baseline characteristics. Among the 1,288 procedures performed, 403 (31.3%) were PCIs. The radial artery was the access site in 381 (29.6%) procedures. The indication was CAD in 1,063 (82.5%) procedures. Right heart catheterization was performed in 217 (16.8%) patients. Urgent procedures were performed in 121 (9.4%) patients, while GP IIb/IIIa inhibitors were used in 125 (9.7%). A total of 122 (9.5%) patients underwent previous CABG. The Angio-Seal closure device was used in 32 (2.5%) procedures. Fellows performed 591 (45.9%) procedures, all via the femoral approach. The mean age of the patients was 62.9 ± 12 years, and 995 (77.3%) were males.
       Primary endpoint. An access site complication occurred in 34 (2.6%) patients. In particular, there were 19 pseudo-aneurysms (18 femoral and 1 radial), 6 femoral A-V fistulae, 6 major hematomas (5 groin and 1 forearm), 2 major bleeding events (1 radial and 1 femoral, two days after Angio-Seal closure), and 1 dissection of the external iliac artery.
       Univariate predictors of local access site complication are shown in Table 1. Variables that were significantly associated with an increased risk of local complications were older age (p < 0.05), female gender (p < 0.001), femoral artery access versus the radial approach (p < 0.01), and arterial puncture performed by the fellow (>p = 0.01).
       On multivariate logistic regression, the only variables that predicted access site complications were female gender (OR 3.2; 95% CI 1.6–6.5) versus male gender; p < 0.001), and the femoral approach (OR 3.9; 1.2–12.1) versus radial access; p < 0.05), while age did not reach statistical significance (p = 0.07). Intriguingly, the role of the fellow was no longer significant at such multivariable adjustment (p = 0.32).
       After exclusion of the transradial procedures, all performed by senior cardiologists, only the transfemoral procedures were analyzed. Patient characteristics according to the operator performing the procedure (fellow versus senior) are reported in Table 2. In this subset of patients, univariate predictors of local complications were older age and female gender (Table 3). On multiple regression analysis, only female gender remained statistically significant (OR 3.3; 1.6–6.9; p = 0.001). Femoral arterial puncture performed by fellows was not associated with an increased incidence of local complications (p = 0.33).
       Secondary endpoints. Overall, MACCE rates were 16 (1.2%): 1 death (0.07%) following a disabling stroke after transradial coronary angiography, 10 myocardial infarctions (3 during radial access procedures and 7 during femoral approach procedures) — all during PCI (2.5% of all PCIs), 3 CVEs (0.2%) — all after transfemoral coronary angiography procedures (1 nondisabling stroke and 2 transient ischemic attacks), and 2 major coronary dissections following PCI (1 femoral and 1 radial) and requiring elective CABG (0.5% of all PCIs). At our institution, all interventional procedures are performed by senior cardiologists, even if the diagnostic catheterization preceding intervention is performed by fellows. Thus, as the majority of MACCE occurred after PCI, senior cardiologists were the operators in charge. Only 1 transient ischemic attack occurred when a fellow was performing the coronary angiography.

Discussion
       To our knowledge, this is the first study showing that left heart catheterization is a safe procedure when performed by cardiology fellows, albeit under the direct supervision of a senior cardiologist. To date, there are only three studies assessing the possible role of trained physician assistants in performing angiography procedures,^14–16 but none have evaluated fellows. The possible explanation for this lack in the medical literature may be due to the accepted fact that fellows must learn case by case and improve their practical skills in interventional cardiology, even if at the cost of a potential slight increase in periprocedural risk.
       Interestingly, a recent paper from a non-university hospital showed that expert operators (> 500 procedures performed) had an overall complication rate lower than cardiologists-in-training (despite the fact that it is not clear if they were cardiology fellows or interventional cardiologists-in-training), with a relative risk reduction of approximately 40%.¹⁰ This result is not confirmed by our report. Indeed, fellows, whose maximum caseload is around 300 procedures during the training period, can safely perform cardiac catheterizations, with a complication rate very similar to that of attending physicians. We focused, in particular, on local vascular complications, as arterial puncture is the first procedure step in the training of fellows and usually the only part of the examination they perform alone. An attending physician, who is directly responsible for the whole procedure, supervises the rest.
       In a recent registry on postcatheterization complications, it was stated: “the involvement of fellows-in-training may have contributed to some complications, especially local”.¹¹ Our study may well complement that report, suggesting the opposite conclusions.
       Local complications. In our study, the 2.6% incidence of local vascular complications is very comparable to some of the studies that evaluated this type of complications after PCI,⁹ while this rate is higher than other studies that considered only diagnostic procedures.¹⁰ Actually, our series collected data from both diagnostic and interventional cases. Nevertheless, other possible explanations for this might be considered. The first explanation could be the difference in “local complication” definitions. Indeed, some studies provided rather vague definitions,^10,17 while others included only complications that necessitated surgical intervention or transfusion.^6,18 Applying this definition to our database, the rate of local complications was nearly halved, as only 9 of 19 pseudoaneurysms required ultrasound-guided compression repair or thrombin injection, 4 of 6 A-V fistulae required surgical repair, 2 of 8 hematomas or bleeding events needed blood transfusion, and the iliac dissection resolved spontaneously. Another possible cause for this increased rate of local complications may be the extensive use of antithrombotic therapy. Indeed, the majority of our patients underwent left heart catheterization because of suspected or known CAD. Thus, they were taking at least one antiplatelet drug despite the fact that it is common practice at our institution to administer a double antiplatelet regimen (aspirin associated with either ticlopidine or clopidogrel) at least 2 days prior to coronary angiography. And for patients with unstable symptoms, we routinely administer subcutaneous unfractionated or low-molecular-weight heparin, which has been shown to significantly increase the risk of local complications.¹⁹ Moreover, in these unstable patients, intravenous heparin was always administered during the procedure, irrespective of the concomitant administration of subcutaneous heparin. Nevertheless, the complication rate in catheterizations performed for reasons other than CAD remained particularly high (3.1%).
       Furthermore, our study’s 3.4% femoral complication rate is slightly higher than the 2.5% incidence observed in a recent study evaluating a large cohort of patients undergoing both diagnostic and interventional procedures.11 Other possible explanations may be the careful inspection and auscultation of the groin performed by trained physicians the day following the procedure (all our patients were admitted on an in-patient basis; none were discharged the same day of the catheterization), and the extensive use of ultrasound evaluation in case of doubt.
       In terms of arterial access site, the radial approach clearly reduced the rate of local complications, with an overall incidence of 0.8% compared to 3.4% after transfemoral catheterizations. A recently published meta-analysis comparing the radial versus the femoral approach for percutaneous coronary diagnostic and interventional procedures, including patients with similar overall characteristics to our patients, yielded results comparable to those of the present study.¹³
       Conversely, the use of a vascular closure device, though only in a few patients, was associated with a higher, albeit not statistically significant, incidence of local complications (6.2% versus 2.5%). Also in this case, a meta-analysis, comparing arterial closure devices with manual compression after cardiac catheterization, confirms our data.²⁰
       Finally and interestingly, local complications were comparable in terms of GP IIb/IIIa inhibitor use (mainly abciximab). This is probably due to the modified heparin dosage in association with abciximab, thus eliminating the excess risk of access site bleeding, as suggested by previous studies.⁸
Major cardiovascular complications. In terms of MACCE, the 1.2% incidence rate observed in our study compares favorably with another recent registry that showed an overall MACCE rate of 3.9%.¹¹ In detail, the death rate was particularly low (0.07%) and was comparable to that of previous large registries,⁶ thus underscoring the overall safety of the procedure, despite the fact that the target population is increasingly at higher risk.²¹ No deaths occurred following PCI, while the rate of myocardial infarction was 2.5%, a rate very similar to what has been reported in the literature.^6,22
       Of interest, the CVE rate was 0.3% (4 of 1,288), with death occurring in 1 case (25% of all CVEs). These data are virtually the same of a recently published report that showed an overall incidence of CVE, after percutaneous coronary procedures, around 0.3%, and a death rate after CVE of 25%.²³
       Study limitations. Retrospective studies obscure several limitations.²⁴ In this case, we used only selected variables that could predict the occurrence of access site complications, particularly those that could be easily extracted from our database. Indeed, several other variables could be important (in particular, as previously stated, antithrombotic regimens other than GP IIb/IIIa inhibitors, body surface area and peripheral vascular disease). Furthermore, the absence of systematic screening for serum CK-MB levels may render our study imprecise in the detection of postprocedural myocardial infarction. Nevertheless, cardiac enzymes were measured extensively and in all cases where there was a clinical suspicion (chest pain, impaired coronary flow, abrupt closure of a side branch).

Conclusions
       Cardiology fellows can safely perform cardiac catheterization procedures without an increase in the rate of local and major cardiovascular complications. Of course, the presence and watchful observation of an attending physician is still of pivotal importance.

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