DCM is a primary myocardial disease of non-ischemic origin (absence of obstructive coronary artery calcification). It is characterised by left ventricular dilatation and impaired left ventricular function. A non-ischemic origin accounts for up to 50% of patients with systolic heart failure (HF) in large HF studies, predominantly due to DCM. Despite advancements in HF treatment, excess mortality in DCM patients remains largely driven by LVEF deterioration and sudden cardiac death (SCD) due to arrhythmia. In the early 2000s the SCD-HeFT study [1] proved that prophylactic ICD implantation, on top of optimal medical therapy, reduces the overall mortality in patients with heart failure with reduced ejection fraction, compared to antiarrhythmic drugs and regardless of the underlying cardiomyopathy. Although this benefit has been clearly demonstrated in case of advanced left ventricular disfunction after myocardial infarction [2], in DCM the DANISH trial [3] downplayed the positive impact of this procedure and the related guidelines recommendations.

CIED placement itself potentially comes with a risk of complications or adverse events [4]. In various investigations, both terms are utilised interchangeably. A reported complication rate of 5–10% is contingent upon factors such as surveillance methods, definitional criteria, and the mode of reporting. Adverse events or complications can be categorised into those associated with the procedure itself and those related to the device. These may encompass pain at the site of insertion, pneumothorax, hematoma formation, vascular or valvular injury, venous thromboembolism, or venous obstruction, cardiac perforation, pericardial effusion, cardiac tamponade, lead dislodgement, generator displacement (Twiddler’s Syndrome), device malfunction, inappropriate shocks, diaphragmatic stimulation, superficial wound infection (minor CIED infection), major CIED infection (pocket infection and infective endocarditis), and mortality. Moreover, complications requiring invasive interventions, such as the insertion of a chest tube for pneumothorax and the early performance of revisions to access the generator (pocket), correspond with increasing procedural volumes. Revision of the CIED pocket is a delicate procedure as it substantially heightens the risk of CIED-related infections. Complications involving lead extraction necessitate specialised instruments and highly skilled personnel, contingent upon the duration the lead has been in place. Such resources may not be readily accessible in all geographical regions, leading to deviations from established guidelines during revisions, which, depending on the circumstances, can result in increased mortality rates [5].

Twiddler’s Syndrome is a rare complication, characterised by dislocation of the generator. The pathophysiological mechanisms underlying Twiddler’s Syndrome involve patient manipulation leading to inadvertent movement or rotation of the implanted device within its pocket. This manipulation can result from various factors such as body habitus, physical activities, or psychiatric conditions predisposing patients to repetitive twisting or manipulation of the device.

Twiddler’s Syndrome often leads to physical displacement of the leads and generator within the subcutaneous pocket. As the leads become twisted or dislodged, their positioning relative to cardiac structures may alter, resulting in abnormal sensing or pacing thresholds. This can lead to inappropriate sensing of signals, such as muscle or electrical artifacts, triggering the device to deliver inappropriate shocks. Furthermore, the displacement of leads may cause alterations in pacing impedance or capture thresholds, potentially leading to pacing failures or inadequate therapy delivery.

There is limited understanding concerning the pathogenesis associated with various other factors, including the types of suture materials used for securing the generator to the muscle fascia, the technique employed for suturing in the subdermal layer (interrupted versus continuous), as well as the materials of the generator and leads. Moreover, colonisation frequencies and their influence on the formation of a fibrous capsule around the generator, with or without calcification, remain poorly elucidated.

Initial placement in a submuscular location [6] or the utilisation of various devices aimed at rapid tissue integration of inert surfaces within the human body, such as an extracellular matrix envelope or an antibiotic-eluting mesh envelope, are strategies employed to address this issue. Nevertheless, outcomes have been inconsistent [7, 8].

In any revision procedure concerning the CIED generator and leads, whether involving lead extraction or replacement to adjust device functionality, complete removal of fibrotic tissues (capsulectomy) is advocated. This process aims to establish a fresh environment for the generator and associated hardware [9,10,11,12]. The approach varies for generator replacement necessitated by battery depletion. In these cases, accessing the fibrous capsule encompassing the old generator should entail subcutaneous preparation directed towards the capsule, commencing from a more cranial incision of the skin. Incisions spanning the generator pocket or extending in lateral, medial, or caudal directions in relation to the pocket should be avoided [13]. If the generator displaces or if there is a loss of subcutaneous tissue or fat, it may protrude through the skin, typically occurring in regions where skin integrity is compromised, such as scar tissue areas [11]. An incision at the caudal end of the fibrous capsule (i.e., break the pocket) during generator replacement for introducing immunocompetent cells is presently discouraged owing to the risk of hematoma formation [5, 14].

In the absence of any cardiac implantable electronic device (CIED) infection, a single-session extraction-reimplantation procedure may be utilised, particularly preferred for pacemaker-dependent patients. In instances of localised CIED infection, such as pocket infection, guidelines currently lack clear recommendations regarding the optimal timing for subsequent de novo placement [5, 14].

In the absence of persistent systemic infection (e.g., negative blood culture screenings or negative FDG-PET computed tomography along the transvenous leads), re-implantation of a new CIED in a contralateral position can be performed. This approach includes utilising infection prevention measures such as antibiotic-eluting mesh envelopes and taurolidine-containing antimicrobial compounds. Empiric antibiotic administration should be initiated based on local resistance patterns, followed by antibiotic administration tailored to susceptibility screening results [15].

Typically, prevailing guidelines encompass the following recommendations:

Prevention

Patient education on avoiding device manipulation is crucial. Proper counselling about device care and potential consequences of manipulation can prevent Twiddler’s Syndrome.

Regular follow-up

Guidelines advise regular visits to monitor device function and detect early signs of Twiddler’s Syndrome. Close surveillance helps identify lead dislodgement or device migration.

Device positioning

Ensuring correct device placement minimises Twiddler’s Syndrome risk. Techniques like submuscular placement or additional anchoring sutures secure the device, reducing manipulation risk.

Prompt intervention

Swift action is vital when Twiddler’s Syndrome is suspected. Interventions may include device repositioning (employing preventative measures against infection), lead extraction, or complete device replacement, based on syndrome severity.

Multidisciplinary Approach

Collaboration involving the “Heart Team” is crucial for comprehensive management. A multidisciplinary approach tailors treatment to each patient’s needs.

Follow-up

Recovery from the procedure was uneventful. During the follow-up, there were no clinical, image or laboratory findings suggesting any adverse event in relation to the procedure or the CIED.

Conclusions

In times of an exponential increase of placement rates of complex CIED systems, complication rates have become a clinically relevant problem. Major complications after CIED placement increase morbidity, re-hospitalisation and mortality [4].

The Twiddler`s syndrome might lead to lead dislodgement and device malfunction. In our case this ultimately led to numerous inadequate shocks.

In absence of an infection, a single session extraction-re-implantation was feasible, employing a transvenous approach for lead extraction with specific tools and constantly disinfecting the surgical site and CIED hardware with an antimicrobial compound adjunct [16].