Corresponding author:
Rajeev Kumar Pathak, MBBS, PhD
Cardiac Electrophysiology Unit, Department of Cardiology
Canberra Hospital, Australian National University
Yamba Drive, Garran, ACT, 2605
Tel: +61 2 6174 8723; Fax: +61 2 6244 4964
E-mail: rajeev.pathak@canberraheartrhythm.com.au
Twitter handle: @drrpathak
Acknowledgments: Dr Sanders is supported by a Practitioner
Fellowship from the National Health and Medical Research Council of
Australia and by the National Heart Foundation of Australia.
Conflict of Interest Disclosures: Dr Sanders reports having
served on the advisory board of Medtronic, Abbott Medical, Boston
Scientific, CathRx and PaceMate. Dr Sanders reports that the University
of Adelaide has received on his behalf lecture and/or consulting fees
from Medtronic, Abbott Medical, and Boston Scientific. Dr Sanders
reports that the University of Adelaide has received on his behalf
research funding from Medtronic, Abbott Medical, Boston Scientific, BD,
and Microport. All other authors have no disclosures. Dr Pathak reports
having served on the advisory board of Medtronic, Abbott Medical, Boston
Scientific. Dr Pathak reports that Canberra Heart Rhythm Foundation has
received on his behalf lecture and/or consulting fees from Medtronic,
Abbott Medical, Boston Scientific and Biotronik. Dr Pathak reports that
Canberra Heart Rhythm Foundation has received on his behalf research
funding from Medtronic, Abbott Medical, Boston Scientific,
and Biotronik.ABSTRACT
Introduction: The prognosis of mixed cardiomyopathy (CMP) in
patients with implanted cardioverter-defibrillators (ICDs) has not been
investigated. We aim to study the demographic, clinical, device
therapies and survival characteristics of mixed CMP in a cohort of
patients implanted with a defibrillator.
Methods: The term mixed CMP was used to categorise patients
with impaired left ventricular ejection fraction attributed to
documented non-ischemic triggers with concomitant moderate coronary
artery disease. This is a single center observational cohort of 526
patients with a mean follow-up 8.7±3.5 years.
Results: There were 42.5% patients with ischemic
cardiomyopathy (ICM), 26.9% with non-ischemic cardiomyopathy (NICM) and
30.6% with mixed CMP. Mixed CMP, compared to NICM, was associated with
higher mean age (69.1±9.6 years), atrial fibrillation (55.3%) and
greater incidence of comorbidities. The proportion of patients with
mixed CMP receiving device shocks was 23.6% compared to 18.4% in NICM
and 27% in ICM. The VT cycle length recorded in mixed CMP (281.6 ±
43.1ms) was comparable with ICM (282.5 ± 44ms; p=0.9) and lesser than
NICM (297.7 ± 48.7ms; p=0.1). All-cause mortality in mixed CMP (21.1%)
was similar to ICM (20.1%; p=0.8) and higher than NICM (15.6%; p=0.2).
Kaplan-Meier curves revealed hazards of 1.57 (95% CI: 0.91, 2.68) for
mixed CMP compared to NICM.
Conclusion: In a cohort of patients with ICD, the group with
mixed CMP represent a phenotype predominantly comprised of elderly with
higher incidence of comorbidities. Mixed CMP resembles ICM in terms of
number of device shocks and VT cycle length. Long-term prognosis of
patients with mixed CMP is worse than NICM and similar to ICM.
Key words: Ischemic cardiomyopathy; Nonischemic cardiomyopathy;
Mixed cardiomyopathy; Implantable-cardioverter defibrillator; Device
shocks; Mortality