By Jeffrey Zimmet, MD, PhD

Associate Professor of Medicine, University of California, San Francisco; Director, Cardiac Catheterization Laboratory, San Francisco VA Medical Center

Dr. Zimmet reports no financial relationships relevant to this field of study.

SYNOPSIS: Researchers studied how well patients retain the information imparted during the informed consent process for cardiac catheterization and concluded that shared decision-making as currently practiced is not particularly robust.

SOURCE: Schwarzman L, Miron-Shatz T, Maki K, et al. Shared decision-making in femoral versus radial cardiac catheterization. Am J Cardiol 2019. [Epub ahead of print].

It is no secret that patients do not understand every aspect of the information presented during informed consent for medical procedures. Through shared decision-making (SDM), the expectation is that patients can understand the risks and benefits of procedures so that they may be partners in their healthcare decisions. In a newly published study, Schwarzman et al reported that patients undergoing cardiac catheterization retain little of the consent discussion, despite an overall high degree of satisfaction with their level of involvement in the decision-making process.

The authors studied patient knowledge of transradial and transfemoral cardiac catheterization following their procedures. They performed a prospective study in a single large, urban, tertiary care, academic center where patients undergoing diagnostic or interventional cardiac catheterization were approached for consent within 48 hours of their procedures, with adequate time such that the effects of sedation had worn off. Then, the investigators verbally presented subjects with an 11-item, open-ended questionnaire designed to assess patient knowledge of cardiac catheterization and the relative risks and benefits of radial and femoral access. A patient knowledge index (PKI) score also was developed to assess each patient’s decision-making, with a maximum score of 6. One hundred patients were enrolled in the study. The mean age was 57 years. Sixty percent were men, 30% were white, and only 23% had completed a college education. Eighty-two percent of patients had radial access for their procedures, with the remainder transfemoral. Forty-three percent of patients expressed a preference for the transradial approach, with only 8% preferring transfemoral and the remainder deferring choice to their physician. Ninety-nine percent of patients correctly named the procedure they had undergone, and 84% could adequately describe the general purpose of their procedure. However, aside from these basics, further understanding was low. Regarding the choice between radial and femoral, fewer than 20% of patients could recall procedure risks for either approach. Only 15% could identify the risks of the approach that they experienced, and 19% correctly identified the risks of the alternative access site. Thirty-one percent correctly described relative benefits of the procedural approach that they underwent, compared with only 11% of the alternative procedural approach (P < 0.001). The average PKI score was 2.6 ± 1.1, with no significant difference in PKI scores between transradial and transfemoral patients. A multivariate analysis identified college-level education with higher PKI scores, while black race was associated with lower scores.

Despite the overall poor retention of knowledge, 96% of study participants indicated that they were satisfied with their degree of involvement in the decision-making process. When asked to rate their level of involvement on a 10-point scale, with 10 representing maximum physician-patient collaboration, patients reported an average score of 8.3. The authors concluded that the implementation of true shared decision-making in the cardiac catheterization laboratory “will require additional efforts.”


At first glance, this study appears to illustrate fatal flaws in the current informed consent paradigm for cardiac catheterization. Before considering this conclusion, we should understand that Schwarzman et al did not test understanding during and immediately after the informed consent process. Rather, they examined information retention by patients up to two days after procedures were performed. The fact that patients did not retain much information about what the investigators were trying to test (specific information about the pros and cons of transradial vs. transfemoral access) is not surprising.

The decision to assess knowledge about specific access site risks and benefits is somewhat artificial and is predicated on the idea that this is one area where patient preference may have some impact. It assumes that patients are a significant part of the decision regarding access site choice under the SDM paradigm. Although patients may wish to receive information about this aspect of the cardiac catheterization procedure, in the majority of cases, physicians choose the access site that they believe will complete the procedure using the best balance of safety and efficacy. In most instances, this depends on the preference and experience of the operators rather than on patient input. Patients who are involved in the decision-making process perceive that they play an active role in their health, which, in theory, can translate into better outcomes through improved medication adherence and lifestyle changes. One fascinating finding in this study was the disconnect between retained patient knowledge and their perceived satisfaction with the decision-making process. Is deeper knowledge unnecessary for patients to make informed decisions? We recognize there is significant variability in patient involvement in preprocedure decision-making, with a sizable proportion of patients wanting their physicians to make the final medical decisions. However, we can do a better job educating patients about the risks and benefits of cardiac catheterization so that informed consent is a robust process for most patients.