Causas de muerte súbita. Problemas a la hora de establecer y clasificar los tipos de muerte

Subcutaneous implantable cardioverter-defibrillator in primary and secondary prevention of sudden cardiac death: A meta-analysis

BACKGROUND

Subcutaneous implantable cardioverter-defibrillator (S-ICD) is gaining in popularity for primary and secondary prevention of sudden cardiac death. The objective was to evaluate the safety and clinical effectiveness of the S-ICD for prevention of sudden cardiac death compared to transvenous cardioverter-defibrillator (TV-ICD).

METHODS

A systematic review with meta-analyses was performed. The electronic databases MEDLINE, EMBASE, SCI, and Cochrane Central Register of Controlled Trials were consulted in March 2018 with no restrictions on publication date. Predefined criteria were used to determine inclusion of studies and to assess their methodologic quality.

RESULTS

Ten longitudinal-observational studies with comparison group presenting moderate methodologic flaws were included (N = 7820). The combination of results indicates that health-related quality of life is not significantly different between S-ICD and TV-ICD groups (Physical health: MD = 2.90; 95% CI = -3.88, 9.68/Mental health: MD = 0.13; 95% CI = -2.11, 2.37). Mortality occurred in 4.4% of S-ICD patients and 5.9% of TV-ICD patients died (OR = 0.79; 95% CI = 0.50, 1.24). The incidence of infections (OR = 1.79; 95% CI = 0.93, 3.43) and inappropriate shocks (OR = 1.28, 95% CI = 0.91, 1.78) is not significantly different between both groups. The S-ICD reduces complications related to electrodes/leads (OR = 0.13, 95% CI = 0.05, 0.29) and has lower electrodes/leads movement compared with TV-ICD (OR = 0.26; 95% CI 0.10, 0.67). In contrast, pneumothorax is more likely in TV-ICD than S-ICD (OR = 0.17; 95% CI = 0.03, 0.97).

CONCLUSIONS

S-ICD reduces electrodes/leads movement, electrodes/leads related complications, and pneumothorax. Our study did not demonstrate a statistically significant difference in mortality, health-related quality of life, and infection rate between S-ICD and TV-ICD.

[Epicardial mapping of reentrant activation during ventricular fibrillation. An experimental study]

INTRODUCTION AND OBJECTIVES

High-resolution epicardial mapping was used in an experimental model to analyze reentrant activation during ventricular fibrillation.

METHODS

In 30 isolated Langendorff-perfused rabbit hearts, recordings were made of ventricular fibrillation activity using an epicardial multiple electrode. In the activation maps with reentrant activation patterns, determinations were made of the number of consecutive rotations, the maximum length of the central core, the area encompassed by the core and two electrodes surrounding it, and the cycle defined by reentrant activation.

RESULTS

Most of the activation maps analyzed showed complex patterns with two or more wave fronts that either collided or remained separated by functional block lines (514 maps, 86%). In 112 maps (19%) activation patterns compatible with epicardial breakthrough of the depolarization process were observed. Reentrant activity was recorded in 42 maps (7%) - the maximum number of consecutive rotations being 3 (mean = 1.3 +/- 0.5). The maximum length of the central core ranged from 3 to 7 mm (mean = 5 +/- 1 mm), while the area encompassed by the central core plus two electrodes surrounding it ranged from 35 to 55 mm2 (mean = 45 +/- 6 mm2). The reentrant cycle length (mean = 47 +/- 8 ms) showed a linear relation to the maximum length of the central core reentry (cycle = 4.52 x length + 24.6; r = 0.7; p < 0.0001).

CONCLUSIONS

a) Epicardial mapping allowed the identification of reentrant activation patterns during ventricular fibrillation in the experimental model used; b) the reentrant activity detected is infrequent and unstable, and c) a linear relation exists between the duration of the cycles defined by reentrant activity and the maximum length of central core reentry.