Antitachycardia pacing for shock prevention in patients with hypertrophic cardiomyopathy and ventricular tachycardia

Introduction: Implantable cardioverter defibrillator (ICD) implantation in patients with cardiac amyloidosis is controversial, with no clear guidelines for clinical decision-making.. The role of ICD implantation in hereditary Transthyretin Amyloid Cardiomyopathy (hATTR-CM) is unclear. We sought to establish the burden of ventricular arrhythmias and the outcomes of ICD implantation in a single center cohort of hATTR-CM patients. Methods: A total of 69 patients with a confirmed diagnosis of hATTR-CM from genetic testing, and technetium pyrophosphate (PYP) scanning, or endomyocardial biopsy underwent retrospective chart review for demographic, clinical, and arrhythmia data. Results: Seventy-four percent of the cohort was male, with a mean age at diagnosis of 68 (SD=18 years). Sixty-five patients (94.2%) patients were African-American; all of whom carried the Valine 122 Isoleucine mutation. Most had systolic heart failure (New York Heart Association Staging II [18, 26%] and III [40, 58.8%]); 37 (54%) patients had an LVEF ≤ 35%. Thirty-six (52.2%) patients had documented episodes of non-sustained ventricular tachycardia (NSVT), three (4.3%) with ventricular tachycardia (VT), and one (1.5%) with ventricular fibrillation (VF). A total of 15 (21.7%) patients had ICDs placed for prevention of sudden cardiac death in the setting of low LVEF (EF <35%). All recorded VT/VF episodes occurred in three patients with ICDs. Of these patients, one experienced two episodes of VT each successfully abated by antitachycardia pacing (ATP), another experienced a single episode of VT abated by ATP, while the final experienced VF with successful 36J shock as well as two episodes of VT each successfully treated with 36J shocks. No inappropriate ICD shocks were delivered, however, there were two instances of ATP for inappropriately detected atrial arrhythmias. Conclusions: In a cohort of patients with hATTR-CM, we observed a high incidence of NSVT, yet only 41% of patients with severe systolic heart failure had ICDs implanted. A high rate of successful defibrillation and no inappropriate ICD shocks were noted, suggesting that ICDs should be strongly considered, and may be underutilized, in patients with systolic heart failure and/or arrhythmias in the setting of hATTR-CM.

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Clinical outcomes and programming strategies of implantable cardioverter defibrillator (ICD) devices during childhood in hypertrophic cardiomyopathy: a UK national cohort study

European Heart Journal ◽

10.1093/ehjci/ehaa946.0733 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

G Norrish ◽

H Chubb ◽

E Field ◽

K McCleod ◽

J Till ◽

...

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Incidence Rate ◽

Clinical Outcomes ◽

P Value ◽

Funding Source ◽

Complication Rates ◽

Antitachycardia Pacing ◽

Icd Implantation ◽

National Cohort ◽

Icd Shock

Abstract Background Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM). ICDs have been shown to be effective at terminating malignant ventricular arrhythmias but at the expense of a high incidence of complications. The optimal device and programming strategies to reduce complications in this patient group are unknown. Purpose To describe the programming strategies and clinical outcomes of ICD implantation in childhood HCM. Methods Anonymised, non-invasive clinical data were collected from a retrospective, longitudinal multi-centre cohort of children (<16 years) with HCM (n=687) and an ICD in-situ from the United Kingdom. Results 96 patients (61 male (64%), 6 non-sarcomeric (6%)) underwent ICD implantation at a median age 14yr (IQR 11–16, range 3–16) and weight 52.3 kg (IQR 34.8–63.1). Indication for ICD was primary prevention in 72 (75%). 82 (85%) had an endovascular system, 3 (3%) epicardial and 11 (12%) subcutaneous system. 61 patients (74%) were receiving one or more cardioactive medications at implantation [B blockers n=66, 70%, disopyramide n=14, 15%, amiodarone n=7, 7%, calcium channel blocker n=7, 9%, other n=5, 6%]. Programming practices varied: all had VF therapies activated (median 220bpm, IQR 212–230); 70 (73%) had a VT zone programmed (median rate 187 bpm, SD 20.9), of which 26 (27%) had therapies activated. 50 patients (61%) had antitachycardia pacing (ATP) activated. Over a median follow up of 53.6 months (IQR 27.3,108.4), 4 patients (4.2%) died following arrhythmic events despite a functioning device. 25 patients had 53 appropriate therapies (ICD shock n=47, ATP n=8), incidence rate 5.22 (95% CI 3.5–7.8). On univariable analysis, secondary prevention indication for ICD implantation was the only predictor of therapy [16 (64%) vs 8 (11.3%), p value <0.001]. 8 (8.3%) patients had 9 inappropriate therapies (ICD shock n=4, ATP n=5), incidence rate 1.37 (95% CI 0.65–2.8), caused by T wave oversensing (n=2), lead migration (n=1), supraventricular tachycardia (n=1). Device complications were seen in 30 patients (31%), including lead complications (n=16) and infection (n=10). No clinical characteristics predicted time to inappropriate therapy or lead complication. Conclusions In a contemporary cohort of children with HCM, the incidence of inappropriate therapies is lower than previously reported, yet complication rates remain higher than reported in adult patients. No clinical, device or programming strategies were associated with inappropriate therapies or lead complications. Funding Acknowledgement Type of funding source: Other. Main funding source(s): British Heart Foundation

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