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Page 10 of 14 Porcari et al. Vessel Plus 2022;6:33 https://dx.doi.org/10.20517/2574-1209.2021.134

benefit following ICD implantation for primary or secondary prevention [70,71] , reasonably due to: (1)
frequent arrhythmias not amenable to defibrillation (i.e., pulseless electrical activity) representing the
[65]
predominant cause of arrhythmic death [71,72] ; (2) higher defibrillation thresholds of infiltrated hearts ; (3)
[73]
significant proportion of non-cardiac death ; and (4) advanced CA at diagnosis carrying ominous
prognosis.

While waiting for trials to yield positive results for SCD prevention in CA, a critical approach to select
candidates for ICD implantation should include age, presumed life expectancy, severity of CA, major
comorbidities increasing competing risks of non-cardiac death, and coexisting conditions with strong
indication for SCD prevention (i.e., documented sustained VT of ventricular fibrillation) [Table 1]. For
instance, ICD implantation for primary prevention might have a role in CA patients with Stage I-II,
previous myocardial infarction, left ventricle (LV) systolic dysfunction, and significant arrhythmic burden
or in those being considered for heart transplantation (HTx) as a “bridge” strategy.

Pacemaker and cardiac resynchronization therapy
The development of LV systolic dysfunction is a late phenomenon in CA, and the majority of patients do
not fulfil criteria for CRT implantation . A significant percentage of patient with CA, especially ATTR-CA,
[68]
have LBBB at diagnosis, amenable of CRT. In addition, in up to 30% of cases , CA is associated with
[74]
conduction abnormalities such as advanced AV block requiring PM implantation with long-term RV
pacing. Notably, PM-dependent patients and those with frequent RV pacing (> 40% of the time) might
benefit from CRT implantation being at higher risk of further functional decline and development of
impaired LVEF with worse HF prognosis . In this population, CRT has been associated with amelioration
[46]
[46]
of the NYHA functional class, LVEF, and reduced mitral regurgitation . The few available data on the
prognostic impact of CRT in CA are controversial [46,75,76] . Indications and timing for CRT implantation in
patients with CA are currently debated [Table 1]. A potential concern for CRT in CA might rise from the
need for higher mean energies to deliver effective therapy due to higher capture thresholds of the infiltrated
heart . In particular, whether CRT may be an effective therapy and should be offered as first-line therapy
[65]
in CA patients requiring frequent RV pacing regardless of the LVEF is unknown. Therefore, based on
current evidence, it is reasonable to consider CRT in patients with CA who meet guideline criteria for
implantation .
[68]

CONCLUSION
Recent advances in the diagnosis and treatment of CA have translated into longer life expectancy of patients
and more challenging clinical scenarios. Compared to the past, patients with CA and HF currently
encountered in clinical practice are a more heterogeneous population and require tailored strategies. The
perception of CA as a treatable disease has opened new possibilities for the management of these patients,
but many grey areas remain to be explored.

DECLARATIONS
Authors’ contributions
Made substantial contributions to conception and structure of the review: Porcari A
Editing and drafting: Porcari A, Pagura L, Varrà GG, Longo F, Rossi M, Saro R, Barbisan D, Cittar M
Revision, supervision and final approval: Rapezzi C, Merlo M

Availability of data and materials
Not applicable.