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

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 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 (

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