Coronary Angiography Using 4 or 6 French Diagnostic Catheters: A Prospective, Randomized Study

Author(s): 

Thierry Lefèvre, MD, Marie Claude Morice, MD, *Raoul Bonan, MD, Pierre Dumas, MD, Yves Louvard, MD, Gaëtan Karrillon, MD, Christophe Loubeyre, MD,
Jean François Piéchaud, MD

Since its introduction by M. Sones in 1962,1 the technique of coronary catheterization has been evolving, allowing for progressive improvements in catheter quality in terms of design as well as external and internal diameter. The progressive reduction in catheter size from 8 French (Fr) to 6 Fr has been associated with a progressive decrease in complications, mainly related to access site,2–4 without affecting image quality. The “gold standard” diameter of catheters for diagnostic coronary angiograms used to be 6 Fr, but now 5 Fr5 or 4 Fr6 catheters with an acceptable lumen for contrast injections are available. Furthermore, contrast media were modified from high osmolality to low osmolality and viscosity was decreased through the use of new agents or heated contrast media facilitating injections. New 4 Fr “large lumen” diagnostic catheters were recently developed. The objective of this study was to prospectively compare the results of diagnostic coronary angiograms via the femoral approach using these new 4 Fr catheters (Infinity, Cordis Corporation, Miami, Florida) compared to the “gold standard” 6 Fr catheters.

METHODS

Each operator performed at least 50 cases with 4 Fr diagnostic catheters prior to the beginning of the study in order to obviate the learning curve. Patients were excluded from the study in the following cases: presence of contraindications to the femoral approach (severe vascular disease, history of surgery), high risk of complications with the femoral approach (obesity, anticoagulant treatment), patient or referring physician preference for the radial approach, significant aortic disease or acute myocardial infarction. Between February and May 1997, all consecutive patients requiring a coronary angiogram were prospectively included in this study. They were randomly assigned (after informed consent in the catheterization laboratory) to coronary angiogram performed with either 4 or 6 Fr Infinity diagnostic catheters. Because of the large number of patients included, the randomization was not stratified. Cross-over to the other group was allowed when one of the two techniques failed. Failure was defined as the inability to achieve selective catheterization and acceptable angiographic quality using the randomized catheter. Handling, selectivity, stability and torque of catheters were graded from 1 (excellent) to 4 (unacceptable) by the operator. Quality of angiograms was assessed by the operator using semi-quantitative evaluation from 1 (unacceptable) to 10 (excellent) as well as by an independent Core laboratory in the Montreal Heart Institute (only 1 reader) in a series of 50 patients matched for gender and weight. An angiographic quality < 7 was defined as non-diagnostic. Angiographic quality was considered non-diagnostic when < 7/10. Injections were performed manually using a low-viscosity, non-heated contrast media (Iomeprol, Bracco, Princeton, New Jersey).
Manual compression was performed immediately after the procedure and ambulation was proposed 2 hours later in the 4 Fr group or 4 hours later in the 6 Fr group. In cases of ad hoc percutaneous transluminal coronary angioplasty (PTCA), hemostasis was obtained using the Perclose device (Redwood City, California) in all cases.

Statistical analysis. Statistical analysis was carried out using SAS 6.08 software. Data were summarized using the mean and standard deviation for continuous variables and frequency for categorical variables. Univariate analysis was performed using the student’s t-test or Chi-square when appropriate.

RESULTS

A total of 405 patients were included in the study (61.4% of all coronary angiograms during the same period), with 199 in the 6 Fr group and 206 in the 4 Fr group. Baseline characteristics of patients are summarized in Table 1. Technical results are displayed in Table 2. No significant differences were observed for left coronary catheters between the 4 and 6 Fr groups. Technical results using the right coronary catheters showed a slight but significant superiority of 6 Fr catheters in terms of handling and torque control. However, the number of catheters used per patient was comparable in both groups. Technical characteristics of pigtail catheters showed that 6 Fr catheters were slightly superior in terms of ease of handling. Angiographic quality results are summarized in Table 3. Although the difference between the 2 groups was moderate, quality of angiograms was significantly superior in the 6 Fr group for the right and left coronary catheters and for pigtail catheters.
Angiographic quality was considered non-diagnostic (< 7/10) for the left coronary angiogram (CA) in 1.6% versus 6.8% of cases using 6 Fr versus 4 Fr catheters (p = NS). By univariate analysis (Table 4), the only predictive factors of non-diagnostic left CA were younger age and higher weight (p = NS). Relations between weight and angiographic quality of the right and left coronary arteries are displayed in Figures 1 and 2. There was no significant correlation but a trend toward better angiographic quality in lighter patients. Core laboratory evaluation performed in only 50 matched patients showed a poorer quality in both groups compared to physician evaluation but the same trend toward better image quality with 6 Fr versus 4 French catheters. However, there was no angiogram judged to be non-diagnostic.
Procedural results are summarized in Table 5. Procedure duration and compression time were slightly shorter in the 4 Fr group, whereas x-ray exposure time and amount of contrast media used were similar in both groups. Ad hoc angioplasty was performed in 20% of cases in both groups using 6 Fr guides. No major event was documented in this series. Ambulation within 2 hours was effectively achieved in 34% of patients in the 4 Fr group versus 15% in the 6 Fr group (p < 0.0001), and within 4 hours in 52% of patients in the 4 Fr group versus 44% in the 6 Fr group (p < 0.05). The rates of minor and moderate hematoma were low and comparable using both techniques. No major hematoma was reported.

DISCUSSION

The results of this prospective, randomized study show that coronary angiography can be performed efficiently and safely using 4 Fr catheters, with an acceptable angiographic quality and earlier ambulation. This was demonstrated in previous studies using 5 Fr and more recently 4 Fr catheters.7–9 From a technical point of view, handling, catheter selectivity, catheter stability and torque control of the left coronary catheters were comparable in both groups. The cross-over rate was higher in the 4 Fr group (3.9% versus 1.5%), but was not significant. Handling difficulty with the right coronary catheter was slightly higher using 4 Fr catheters (1.34 ± 0.77 versus 1.16 ± 0.55; p = 0.007) and the torque control was fairly lower (1.10 ± 0.39 versus 1.20 ± 0.58; p = 0.041). Nevertheless, the cross-over rate was again not significantly different (1.0% versus 5.4%; p = NS).
According to both operator and Core lab assessment, angiographic quality was slightly lower when comparing 4 Fr versus 6 Fr catheters. This difference in angiographic quality evaluated both by physician and Core lab was moderate and resulted in non-diagnostic left coronary angiography in a higher but non-significant proportion of patients in the 4 Fr group by physician evaluation (6.8% versus 1.4%; p = NS). Furthermore, the use of 4 Fr catheters was not a predictive factor of non-diagnostic coronary angiograms. However, the gold standard for quantitative coronary angiography remains to date 6 Fr catheters.
The 2-minute reduction in procedure time using 4 Fr catheters compared to 6 Fr was significant and probably related to the absence of catheter occlusion, especially in the right coronary artery with 4 Fr catheters. Furthermore, compression time was significantly shorter, by 1 minute, with 4 Fr compared to 6 Fr catheters. Very early (<= 2 hours) and early ambulation (<= 4 hours) was obtained more frequently in the 4 Fr group (34% versus 15%; p < 0.0001 and 52% versus 44%, respectively; p < 0.05). Finally, the rate of access-site complications was low, irrespective of the guiding catheter size, as no major hematomas and only 1% moderate hematomas were reported in both groups.
Since all patients were consecutive, the results of this study can be applied to the general population of patients with no contraindications to the femoral approach. The use of 4 Fr catheters has many advantages: smaller access site, no pressure “dumping” in the right coronary artery, and earlier ambulation. The only limitation to the use of 4 Fr catheters is the angiographic quality, which is moderately but significantly lower in this study using hand injections and low-viscosity contrast media.


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