The incidence of patients who are not responsive to cardiac resynchronization therapy (CRT) was found to be high, according to a study published in the Journal of the American College of Cardiology.

Researchers evaluated participants who received CRT devices between January 2013 and November 2015 at 69 centers worldwide (n=1524). The total number of patients evaluated after study withdrawal, death, or missed 6-month follow-up was 1327. Eligible patients were enrolled ≤30 days following the successful implant with any market-approved Abbott CRT pacemaker or CRT defibrillator device with quadripolar LV leads.

Study sites recorded baseline patient demographics, clinical characteristics, comorbidities, guideline-directed medical regimens and antiarrhythmic drugs, and system implantation details. All patients were followed either remotely via telephone, or in-office every 3 months for 1 year. CRT response status was assessed once at the in-office 6-month follow-up visit. Response to CRT was determined using the clinical composite score (CCS) and by site-specific definition, based on each site’s standard clinical care assessments and functional tests for CRT response.

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The incidence of site-defined black of response to CRT was 20%, based on clinical events and clinical functioning assessments, and 31%, based on objective CCS score. Site-defined nonresponders received treatment more often than responders (55.9% vs 38.3%, respectively; P <.001), primarily consisting of medication changes (36.1%) and heart failure education (36.6%). At the 6-month follow-up, 44.1% of patients classified as nonresponders by site-specific definition (n=105 of 238) received no additional treatment.

This study was limited by the use of a registry protocol that did not mandate baseline data collection, and by the fact that lead positions varied across sites. In addition, CCS scoring was limited in that a single hospitalization event for heart failure could qualify a patients as nonresponsive, and in that observations related to temporal profiles, frequency, and duration of heart failure hospitalizations were not captured in this scoring system.

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“In a diverse international, contemporary cohort, patients treated with CRT were sicker/more challenging with a large contingent that remained non-responders, who were mostly passively managed and remained at risk,” the researchers concluded. “Non-responders require rigorous attention to accurate diagnosis (which may be facilitated by an objective assessment such as CCS), follow-up intensification and integration with cross-disciplinary care, and exploration of effective interventions. This is an unmet need among high-risk heart failure patients.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Varma N, Boehmer J, Bhargava K, et al. Evaluation, management, and outcomes of patients poorly responsive to cardiac resynchronization device therapy. J Am Coll Cardiol. 2019;74(21):2588-2603.