Review of “Referring Physicians’ Discordance With the Primary Prevention ICD Guidelines: A National Survey”

Editor’s Note: This article is based on Castellanos JM, Smith LM, Varoys PD, Dehlendorf C, Marcus GM. Referring physicians’ discordance with the primary prevention implantable cardioverterdefibrillator guidelines: A national survey. Heart Rhythm 2012;9:874–881.


Although ICD therapy has become a mainstay in the treatment strategy to reduce the incidence of sudden cardiac death, concerns persist about when these potentially lifesaving devices should be used with data suggesting that both underutilization and overutilization of this therapy exist. This study is a prospective survey analysis of referring physician concordance with accepted guideline-based referral patterns for primary prevention ICD implantation among both primary care physicians (family medicine and internal medicine) and general cardiologists.1


A sample survey was distributed to 3,000 practicing American physicians with questions designed to address (1) physician understanding of the 2008 ACC/AHA/HRS guidelines for primary prevention ICD implantation, (2) physician perception of ICD-related complications and reasons why patients may not be referred for ICD implantation and (3) baseline physician demographic status and practice habits and how those factors might influence referral decisions.


Among respondents 28% (95% confidence interval [CI]: 25%–30%) do not refer patients to a subspecialist for consideration of a primary prevention ICD implantation including 44% of family medicine physicians, 24% of internal medicine physicians and 9% of cardiologists. A multivariate analysis of characteristics among physicians with a pattern of referring at least a proportion of their patients for consideration of a primary prevention ICD implantation identified cardiologists (p=0.003), physicians with more patients older than 60 years (p=0.015) and physicians with a practice pattern of referring to an electrophysiologist (p<0.001) as groups associated with a higher tendency to refer patients for a possible primary prevention ICD implantation. In a multivariable analysis, restricted to cardiologists, board certification in cardiology was the only independent predictor of referral (p< 0.001) with an odds ratio of 7.4:1.0. Interestingly, the respondents reported their belief that they referred 85% of their patients, whom they considered as having an appropriate indication for a primary prevention ICD implantation.

A number of cardiology practice patterns, discordant with established guidelines, were reported including 4% of physicians, who believed that a primary prevention ICD is never indicated in the absence of a malignant ventricular arrhythmia (95% CI: 2%–6%); 19% who believed that a primary prevention ICD can be indicated within 40 days of a myocardial infarction (95% CI: 15%–22%) and 25% who believed that an LVEF of > 40% is an appropriate cutoff for a primary prevention ICD (95% CI: 21%–29%). Those primary care physicians, who independently manage their LV dysfunction patients without referring to a subspecialist, were not more likely provide answers more consistent with the guidelines.

Higher levels of concern about device infection risk and painful ICD discharges were the only two belief differences between those who refer for consideration of a primary prevention ICD vs. those who do not refer. The presented summary of the Likert scales, assessing a number of potential factors of concern when deciding against making a referral, demonstrate that patient preference is the most important factor cited by referring physicians limiting referral while cost to the national healthcare system, loss of patient and device recall were not concerns.


Based upon the survey results presented in this study it appears that a moderate number of both family medicine and internal medicine physicians do not refer patients for consideration of a primary prevention ICD implantation. Furthermore physician perspectives about primary prevention ICD implantation indications appear to be discordant with the published guidelines. The authors suggest that physician beliefs may constitute an important barrier to patient referral.


Sudden cardiac death remains a leading cause of death in the United Sates. Over the past several decades many prospective, randomized clinical trials have demonstrated the benefit of the implantable cardioverter-defibrillator in reducing the incidence of sudden cardiac death in selected high-risk patient populations when employed as a primary prevention strategy.2-5 Based upon these landmark studies guidelines have been published6-7 and the Center for Medicare & Medicaid Services has defined a primary prevention ICD coverage policy.8

Despite the guideline publications and coverage policies, developed to minimize practice variation and base clinical decision-making on existing data, concerns about the appropriate use of ICDs persist with conflicting studies suggesting that implantable defibrillators are both underutilized9 and overutilized,10 possibly in a manner inconsistent with the published guidelines.

In this study the authors focus upon the practice patterns of physicians, who make decisions about which patients are referred for consideration of a primary prevention ICD implantation. They provide data demonstrating that many referral patterns are not concordant with the primary prevention ICD guidelines. Between 24-44% of primary care physicians and a smaller percentage of cardiologists do not refer any patients for consideration of a primary prevention ICD. Among those, who do refer patients, many do so in conflict with the published guidelines with incongruities including an incorrect perception of a concomitant need for a ventricular arrhythmia (15%), an erroneous assessment of the LVEF at which a primary prevention ICD is indicated (36%) and a lack of knowledge about the requisite timeframe after a myocardial infarction that must be observed before an ICD can be implanted (25%). The authors suggest that a knowledge gap and the existence of strongly held personal beliefs possibly influence the decision-making process.

The study is limited by its survey methodology and the obvious potential selection biases that characterize such studies. However the message that derives from the study rings loudly and clearly. It is supported by analyses performed in other medical arenas that also demonstrate a lack of adherence to established guidelines such as screening processes (e.g. mammograms for breast cancer, colonoscopy for colon cancer, etc.) and treatment protocols (e.g. lipid management to cholesterol goal, hypertension management to defined blood pressure goal, diabetes management to HbA1c goal, etc.). The existing literature, with the findings of this study adding additional supporting data, suggests that, despite published guidelines, the ability to achieve guideline-driven outcomes is often lacking.

This study importantly demonstrates the need to address the barriers to effective guideline-driven practices for the prevention of sudden cardiac death. As the authors suggest, the solution is probably multifactorial including the need to develop and initiate educational programs, the importance of addressing physician and patient beliefs, concerns and fears in addition to the development of systematic team-based guideline-driven processes. Further research, using both registry data and prospective study formats, to define more accurately the patient populations that might benefit more consistently from this therapy, are also needed.


  1. Castellanos JM, Smith LM, Varoys PD, Dehlendorf C, Marcus GM. Referring physicians’ discordance with the primary prevention implantable cardioverterdefibrillator guidelines: A national survey. Heart Rhythm 2012; 9:874–881.
  2. Moss AJ, Hall WJ, Cannom DS, et al; Multicenter Automatic Defibrillator Implantation Trial Investigators. Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. N Engl J Med 1996; 335:1933–1940.
  3. Buxton AE, Lee KL, Fisher JD, Josephson ME, Prystowsky EN, Hafley G, Multicenter Unsustained Tachycardia Trial Investigators. A randomized study of the prevention of sudden death in patients with coronary artery disease. N Engl J Med 1999; 341:1882–1890.
  4. Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med 2002; 346:877–883.
  5. Bardy GH, Lee KL, Mark DB, et al. Amiodarone or an implantable cardioverter defibrillator for congestive heart failure. N Engl J Med 2005; 352:225–237.
  6. Epstein AE, DiMarco JP, Ellenbogen KA, et al. ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices). J Am Coll Cardiol 2008;51(21):e1-62
  7. Hunt SA, Abraham WT, Chin MH, et al. ACC/AHA 2005 Guideline Update for the Diagnosis and Management of Chronic Heart Failure in the Adult: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Update the 2001 Guidelines for the Evaluation and Management of Heart Failure). J Am Coll Cardiol 2005;46(6):e1-82.
  8. Centers for Medicare & Medicaid Services. National Coverage Determination (NCD) for Implantable Automatic Defibrillators (20.4). [Last Accessed July 23, 2012].
  9. Bradfield J, Warner A, Bersohn MM. Low referral rate for prophylactic implantation of cardioverter-defibrillators in a tertiary care medical center. Pacing Clin Electrophysiol 2009; 32:S194 –S197.
  10. Al-Khatib SM, Hellkamp A, Curtis J, et al. Non-evidence-based ICD implantations in the United States. JAMA 2011; 305:43– 49.

Clinical Topics: Arrhythmias and Clinical EP, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias

Keywords: Death, Sudden, Cardiac, Incidence, Internal Medicine, Primary Prevention, Defibrillators, Implantable

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