[History of the implantable cardioverter-defibrillator in Germany]

The implantable cardioverter-defibrillator (ICD) was a breakthrough in the prevention of sudden cardiac death. After years of technical development in the USA, Michel Mirowski succeeded in proving reliable automatic defibrillation of ventricular tachyarrhythmias through initial human implantations in 1980, despite many obstacles. Nearly 4 years later, the first patients received ICDs at multiple centers in Germany. Subsequently, outside the USA, Germany became the country with highest implantation rates. The absolute number of implantations remained small as long as implantations required epicardial defibrillation electrodes and therefore thoracotomy by cardiac surgeons. Pacemaker-like implantation using a transvenous defibrillation electrode with a pectoral ICD became feasible in the early 1990s pushing implantation rates to the next level. Technical advancements were accompanied by clinical research in Germany, and often, the first-in-human studies were conducted in Germany. In 1991, the first guidelines for indications were established in the USA and Germany. Several randomized studies on indications were published between 1996 and 2009, mostly led by American teams with German participation, but also under German leadership (CASH, CAT, DINAMIT, IRIS). The DANISH study in 2016 questioned the results of these long-standing studies. Instead of providing ICDs to patients using a broad indication, future efforts aim to identify patients who, despite optimal medical therapy, cardiac resynchronization therapy (CRT), and/or catheter ablation, need protection against sudden cardiac death. Risk scores incorporating myocardial scars in magnetic resonance imaging (MRI) and genetic information are expected to contribute to more individualized and effective indications.

EHRA expert consensus statement and practical guide on optimal implantation technique for conventional pacemakers and implantable cardioverter-defibrillators: endorsed by the Heart Rhythm Society (HRS), the Asia Pacific Heart Rhythm Society (APHRS), and the Latin-American Heart Rhythm Society (LAHRS)

With the global increase in device implantations, there is a growing need to train physicians to implant pacemakers and implantable cardioverter-defibrillators. Although there are international recommendations for device indications and programming, there is no consensus to date regarding implantation technique. This document is founded on a systematic literature search and review, and on consensus from an international task force. It aims to fill the gap by setting standards for device implantation.

Effectiveness of single- vs dual-coil implantable defibrillator leads: An observational analysis from the SIMPLE study

INTRODUCTION

Dual-coil leads (DC-leads) were the standard of choice since the first nonthoracotomy implantable cardioverter/defibrillator (ICD). We used contemporary data to determine if DC-leads offer any advantage over single-coil leads (SC-leads), in terms of defibrillation efficacy, safety, clinical outcome, and complication rates.

METHODS AND RESULTS

In the Shockless IMPLant Evaluation study, 2500 patients received a first implanted ICD and were randomized to implantation with or without defibrillation testing. Two thousand and four hundred seventy-five patients received SC-coil or DC-coil leads (SC-leads in 1025/2475 patients; 41.4%). In patients who underwent defibrillation testing (n = 1204), patients with both lead types were equally likely to achieve an adequate defibrillation safety margin (88.8% vs 91.2%; P = 0.16). There was no overall effect of lead type on the primary study endpoint of "failed appropriate shock or arrhythmic death" (adjusted HR 1.18; 95% CI, 0.86-1.62; P = 0.300), and on all-cause mortality (SC-leads: 5.34%/year; DC-leads: 5.48%/year; adjusted HR 1.16; 95% CI, 0.94-1.43; P = 0.168). However, among patients without prior heart failure (HF), and SC-leads had a significantly higher risk of failed appropriate shock or arrhythmic death (adjusted HR 7.02; 95% CI, 2.41-20.5). There were no differences in complication rates.

CONCLUSION

In this nonrandomized evaluation, there was no overall difference in defibrillation efficacy, safety, outcome, and complication rates between SC-leads and DC-leads. However, DC-leads were associated with a reduction in the composite of failed appropriate shock or arrhythmic death in the subgroup of non-HF patients. Considering riskier future lead extraction with DC-leads, SC-leads appears to be preferable in the majority of patients.

Comparison of single-coil lead versus dual-coil lead of implantable cardioverter defibrillator on lead-related venous complications in a canine model

PURPOSE

Dual- coil lead (DCL) of implantable cardioverter defibrillator (ICD) is preferred clinically in patients. However, it is related to higher risk of venous stenosis and thrombosis. The present study was done to compare the fibrosis and extraction of the leads between the single-coil lead (SCL) and DCL in animal models.

METHODS

This was a chronic animal study with a follow-up duration of 6 months. Twenty mongrel dogs were randomly divided into DCL group or SCL group. Venography was performed before the sacrifice to evaluate the venous stenosis in vivo. The maximum pulling-out tension of the ICD lead was measured by a tensometer. Hematoxylin-eosin stain and toluidine blue O stain were applied to show the pathological changes of the superior vena cava (SVC) to evaluate the fibrosis and the thickness of the SVC adjacent to the leads.

RESULTS

The DCL group showed higher incidence of venous stenosis (OR = 31.5; 95% CI, 2.35-422.3; p = 0.005). It revealed increased tension to extract the leads in the DCL group (5.96 ± 1.86 vs. 3.68 ± 1.46 N, p = 0.027). The difference of venous wall thickness of SVC was 4.3 ± 0.3 fold-changes between two groups (p = 0.007). Moreover, the degree of venous wall fibrosis in DCL group was more serious than that it in SCL group (3.61 ± 1.26 vs. 1.08 ± 1.35 mm², p = 0.015).

CONCLUSION

The DCL was proved to increase thrombosis, fibrosis, and stenosis in the SVC. Likewise, the DCL was mechanically harder to be extracted than the SCL. Our study showed that lead-related complications of the DCLs were higher than those of the SCLs regardless of the equal defibrillation thresholds between them. Results of the present study would help to choose the proper lead which could be removed.