Referral, Appropriateness and Eligibility of Implantable Cardioverter Defibrillator Therapy in Alberta

• Author / Creator

  Bernier, Rochelle

• Background: Sudden cardiac death (SCD) is responsible for 50% of all cardiovascular deaths and is primarily due to rapid, life-threatening heart rhythm abnormalities. Multiple large, randomized clinical trials have demonstrated that implantable cardioverter defibrillator (ICD) therapy reduces morbidity and mortality in patients with heart failure and an impaired ejection fraction at risk for SCD or patients who have suffered a life-threatening ventricular arrhythmia. Although guidelines exist to help identify patients who may benefit from device therapy, sparse data exists evaluating the referral, appropriateness and eligibility of ICD therapy in clinical practice. Aims: This thesis has three main aims: (i) to evaluate referring physician’s knowledge regarding indications for primary prevention ICD and to identify potential barriers for referral (Project 1), (ii) to evaluate adherence to guideline recommendations and appropriate use criteria for patients who underwent ICD therapy and to identify reasons for non-evidence based implants (Project 2) and (iii) to determine the rates of ICD eligibility and utilization among patients seen in heart function clinic and to identify reasons for non-implantation (Project 3). The work performed for this thesis was part of a quality improvement initiative performed by the Arrhythmia Working Group of the Alberta Health Services Cardiovascular and Stroke Strategic Clinical Network.Methods/Results:Project 1: A web-based survey consisting of demographics, practice characteristics, case scenarios regarding indications for a primary prevention ICD and a list of potential barriers for referral was administered to Internists, Cardiologists and Cardiology Residents in Alberta. The survey response rate was 14%. Among respondents, 55% were Internists, 32% Cardiologists and 13% Cardiology Residents. Overall, 34% of physicians provided answers concordant with guidelines. In multivariable analysis, predictors of complete guideline concordance were being a Cardiologist (odd ratio (OR) 5.9, confidence interval (CI) 2.1-16.4, p=0.001) and Cardiology Resident (OR 6.7, CI 1.7-27.3, p=0.007). The most common barrier for referral for Internists was lack of confidence in knowledge of guideline recommendations; while Cardiologists reported concerns about cost-effectiveness and Cardiology Residents were most concerned with inappropriate shocks. Project 2: A retrospective review of ICD procedures from January 1st, 2015-December 31st, 2016 in Alberta was performed. Implants were classified as Class I/IIa/IIb/III according to 2008 ACC/AHA/HRS ICD guidelines and 2012 ACCF/AHA/HRS Focused Update, yes/no according to 2013 Canadian Cardiovascular Society(CCS) cardiac resynchronization therapy(CRT) guidelines and ‘appropriate’/‘maybe appropriate’/‘rarely appropriate’ according to 2013 AUC. There were 1300 ICD procedures over the 2-years. Among all implants, 0.3% of primary prevention, 0.7% of secondary prevention implants and 0.2% of generator replacements were non-evidence based. Among CRT implants, 11% were inconsistent with CCS recommendations. When applying AUC, 92% of implants were classified ‘appropriate’ and 4% did not meet a recommendation. For both guideline recommendations and AUC, overlapping reasons for non-adherence existed, including QRS width 0.35 (n=2) and recent myocardial infarction (n=1). The AUC had no existing criteria in 3% (n=41) of procedures.Project 3: A retrospective chart review of consecutive patients seen at two heart function clinics in Edmonton and Calgary from 2012-2015 was performed to determine device eligibility by collecting demographics, clinical indications, comorbidities and to identify reasons for non-implantation. A total of 1294 patients were seen in HF clinic. Yearly rates of device eligibility and utilization ranged from 32-52% and 19-56%, respectively. When a documented reason for non-implantation existed, yearly utilization rates increased to 36-64%. Independent predictors of non-implantation were age>75 years (OR 1.80, 1.23-2.63), LVEF≤0.35 (OR 4.69, 2.74-8.04), kidney disease (OR 1.71, 1.04-2.80) and cancer (OR 2.56, 1.23-5.34). Almost half of the time (46%), there was no documented reason for non-implantation among eligible patients.Conclusions: These data suggest: (i) knowledge regarding indications for primary prevention ICD is limited and varies among referring physicians, with Cardiologist and Cardiology Residents most familiar with ICD indications. Overall barriers for referral included cost of ICD therapy, lack of confidence in knowledge of ICD guidelines and risk of inappropriate shocks, (ii) that a formal process of specialist evaluation, eligibility reminders on device requisitions and peer-review consensus resulted in less than 1% of non-evidence-based ICD procedures and (iii) that less than half of eligible patients receive an ICD and reasons for non-implant are often missing. This thesis may help to inform future initiatives that can lead to efficient and effective delivery of ICD therapy.

• Subjects / Keywords

  • Sudden Cardiac Death
  • Implantable Cardioverter Defibrillator
  • Quality Improvement

• Graduation date

  Spring 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3PK07H11

• License

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