Guideline-Directed Medical Therapy in Patients After Implantation of Implantable Cardioverter Defibrillators to Improve Long-Term Outcomes

November 25, 2025 updated by: Ratika Parkash

Guideline-directed medical therapy (GDMT) and the mortality benefit it provides in the heart failure with reduced ejection fraction (HFrEF) population are well-established by multiple professional society guidelines. GDMT refers to initial medical therapy with angiotensin-converting enzyme inhibitors (ACEi) or angiotensin-receptor blockers (ARB), beta-blockers (BB), and mineralocorticoid receptor antagonists (MRA) titrating to maximally tolerated doses for patients with HFrEF. Cardiac implantable electronic devices (CIEDs) such as the implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT) have also become a mainstay in the management of HFrEF after implementation of GDMT. ICD therapy is an effective and established treatment for HFrEF patients for both primary and secondary prevention of SCD.

Regarding the use, adherence and results of GDMT after ICD/CRT implantation, there is very limited data available in the literature. There are a few retrospective trials that show this, however very limited randomized controlled data.

This proposed study would randomize patients with primary prevention ICDs and CRT into a specialized clinic with a heart failure nurse practitioner vs usual clinical care, with the goal of determining outcomes such as change in LVEFs, heart failure hospitalizations, and visits to the ER for heart failure. Consequently, this would determine whether targeted clinics are needed for ICD/CRT patients with HFrEF to optimize GDMT, improve patient outcomes and thus implement new guidelines/recommendations for this specific patient population.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Guideline-directed medical therapy (GDMT) and the mortality benefit it provides in the heart failure with reduced ejection fraction (HFrEF) population are well-established by multiple professional society guidelines. GDMT refers to initial medical therapy with angiotensin-converting enzyme inhibitors (ACEi) or angiotensin-receptor blockers (ARB), beta-blockers (BB), and mineralocorticoid receptor antagonists (MRA) titrating to maximally tolerated doses for patients with HFrEF. Cardiac implantable electronic devices (CIEDs) such as the implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT) have also become a mainstay in the management of HFrEF after implementation of GDMT. ICD therapy is an effective and established treatment for HFrEF patients for both primary and secondary prevention of SCD. Canadian guidelines recommend ICD implantation for patients with ischemic or non-ischemic cardiomyopathy (NICM) and persistent ejection fraction ≤ 30%, when persistent refers to at least 3 months of optimal medical therapy (OMT) in all patients and, in patients with ischemic heart disease, at least 3 months after revascularization and at least 40 days after a myocardial infarction (MI). These guidelines also suggest that ICDs be considered for the same population with a left ventricular ejection fraction (LVEF) of 31-35% as well. CRT device therapy is indicated for use in patients in sinus rhythm with New York Heart Association (NYHA) class II-III, or ambulatory NYHA class IV heart failure symptoms, a LVEF ≤ 35%, and QRS duration > 130 ms because of left bundle branch block (LBBB).

The use and adherence to GDMT before and after ICD implantation is of critical importance. Adherence to GDMT before implantation has the potential to improve survival and may even improve left ventricular ejection fraction (LVEF) enough so that an ICD may no longer be indicated. However, adherence to GDMT is notoriously difficult to assess in conventional clinical practice due a multitude of factors. These include information about outpatient prescription use, prescription filling pattern/barriers, reported patient adherence to GDMT, and various electronic health records/documentation linked to pharmacies to name a few. In one retrospective study, it was demonstrated that just over half (61.1%) of patients filled any GDMT prescription before ICD implantation. Futhermore, patients receiving GDMT versus those who did not receive GMT had a lower 1 year mortality rate after ICD implantation (11.1% vs 16.2%) after adjustments for comorbidities, LVEF, and NYHA class heart failure. In a similar study assessing prescriptions claim data to assess beta-blocker use prior to ICD implantation, the median number of days covered by a beta-blocker in the 90 days prior to ICD implantation was 46 days. From the results of these studies, it is clear that there is room for improvement for implementation of GDMT prior to ICD implantation.

Regarding the use, adherence and results of GDMT after ICD/CRT implantation, there is very limited data available in the literature. One of the first studies to exhibit the effect of medical therapy in HFrEF patients after ICD/CRT implantation was a retrospective cohort study that stratified ICD/CRT patients according to combination treatment with HFrEF medical therapy; patients on none or one HFrEF medications were in group 0/1, patients on two HFrEF medications (ex: ACEi + BB) were in group 2, and patients on all three HFrEF medications (ACEi/ARB + BB + MRA) were in group 3. Results showed a higher hospitalization rate per patient/year in the undertreated population (group 0 and 1) (28% vs 12%, p = 0.001). Also, in multivariate analysis, patients treated with better medical therapy (groups 2 and 3) had less hospitalizations for heart failure and better survival (p < 0.001). In addition to benefits with hospitalizations and better survival, adjunctive optimization of GDMT can result in quantitative benefits as well. One study compared usual post-implant care was compared to protocol-driven clinical care with a dedicated nurse and cardiologist. Protocol-driven care was associated with significant improvements in LVEF, LV internal diastolic diameter, and improvements in maximum exercise capacity. Interestingly, these improvements appeared to be driven not only by device-related management, but also by concomitant optimization of GDMT and heart failure education. As evidenced by these promising results, it is of utmost importance to assess and optimize the use of GDMT in patients with CIEDs and HFrEF, as there can be potential improvements in LVEF, exercise capacity and survival.

This proposed study would randomize patients with primary prevention ICDs and CRT into a specialized clinic with a heart failure nurse practitioner vs usual clinical care, with the goal of determining outcomes such as change in LVEFs, heart failure hospitalizations, and visits to the ER for heart failure. Consequently, this would determine whether targeted clinics are needed for ICD/CRT patients with HFrEF to optimize GDMT, improve patient outcomes and thus implement new guidelines/recommendations for this specific patient population.

Study Type

Interventional

Enrollment (Actual)

29

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Nova Scotia
      • Halifax, Nova Scotia, Canada, B3H 3A7
        • QEII Health Sciences Centre

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

14 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

- patients who underwent ICD or CRT (pacemaker or defibrillator) implantation therapy at the QEII Health Sciences Centre between 2002 and 2019 and had a left ventricular ejection fraction ≤ 35% at the time of the initial implantation.

Exclusion Criteria:

  • unable to provide informed consent, has a life expectancy of less than one year, dementia, cirrhosis, or metastatic malignancy.
  • Patients who underwent primary prevention ICD implantation for arrhythmogenic right ventricular cardiomyopathy (ARVC), ion channelopathies, hypertrophic cardiomyopathy, or infiltrative cardiomyopathy will be excluded from this analysis.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Supportive Care
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
No Intervention: Usual clinical care
In this arm, patients with devices and heart failure will undergo usual clinical care. This consists of follow-up as deemed necessary by their primary care providers.
Experimental: Specialized clinic

In this arm, patients with devices and heart failure will be enrolled in a specialized clinic with the following aims:

  1. Referral to a heart failure nurse practitioner to undergo optimization of medical therapy.
  2. Optimization of device programming with reduction of ventricular pacing where possible, rate responsiveness when indicated.

  3. For those patients with CRT - ECG optimization using a previously tested protocol will be performed. This will consist of attempts to achieve the shortest QRS duration with the following guidelines:

    1. Two BV fusion patterns in leads V1 and V2: QRS normalization or a new or an increased R wave.
    2. QRS difference ≤-25 ms. Remodelling probability increases as QRS difference takes on larger negative values (QRS difference = BV paced QRS - LBBB QRS duration, in ms).
Other: Specialized heart function clinic
This information has already been provided.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Left Ventricular Ejection Fraction (LVEF)
Time Frame: 1 year
The proportion of patients that experience more than 10% increase in LVEF. This outcome will demonstrate if the experimental group had benefit in their heart function (ie LVEF). A successful outcome is if the patient demonstrated an increase by at least 10% in the LVEF over the year of follow up.
1 year

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Mortality rate
Time Frame: 1 year
All-cause mortality will demonstrate if the two groups differed in the absolute number of mortality in the 1 year follow up period.
1 year
Heart failure hospitalization frequency
Time Frame: 1 year
This will determine if the experimental group patients were hospitalized with a different frequency compared to the usual care group during the 1 year follow up period.
1 year
Rate of adherence to guideline directed medical therapy
Time Frame: 1 year
This outcome will be based on self-reported adherence to combinations of medications for treating heart failure. Patients will provide us details of adherence to their medications as best as possible.
1 year

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Ratika Parkash

Collaborators

Nova Scotia Health Authority

Investigators

  • Principal Investigator: Ratika Parkash, MD, NSHA

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

June 1, 2021

Primary Completion (Actual)

December 1, 2023

Study Completion (Actual)

August 31, 2024

Study Registration Dates

First Submitted

July 23, 2020

First Submitted That Met QC Criteria

August 5, 2020

First Posted (Actual)

August 7, 2020

Study Record Updates

Last Update Posted (Actual)

November 26, 2025

Last Update Submitted That Met QC Criteria

November 25, 2025

Last Verified

November 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ICD-GDMT

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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