Amplitude spectral area of ventricular fibrillation and defibrillation success at low energy in out-of-hospital cardiac arrest

The optimal energy for defibrillation has not yet been identified and very often the maximum energy is delivered. We sought to assess whether amplitude spectral area (AMSA) of ventricular fibrillation (VF) could predict low energy level defibrillation success in out-of-hospital cardiac arrest (OHCA) patients. This is a multicentre international study based on retrospective analysis of prospectively collected data. We included all OHCAs with at least one manual defibrillation. AMSA values were calculated by analyzing the data collected by the monitors/defibrillators used in the field (Corpuls 3 and Lifepak 12/15) and using a 2-s-pre-shock electrocardiogram interval. We run two different analyses dividing the shocks into three tertiles (T1, T2, T3) based on AMSA values. 629 OHCAs were included and 2095 shocks delivered (energy ranging from 100 to 360 J; median 200 J). Both in the "extremes analysis" and in the "by site analysis", the AMSA values of the effective shocks at low energy were significantly higher than those at high energy (p = 0.01). The likelihood of shock success increased significantly from the lowest to the highest tertile. After correction for age, call to shock time, use of mechanical CPR, presence of bystander CPR, sex and energy level, high AMSA value was directly associated with the probability of shock success [T2 vs T1 OR 3.8 (95% CI 2.5-6) p < 0.001; T3 vs T1 OR 12.7 (95% CI 8.2-19.2), p < 0.001]. AMSA values are associated with the probability of low-energy shock success so that they could guide energy optimization in shockable cardiac arrest patients.

Ventricular fibrillation amplitude spectral area as a guide to deliver the optimal energy level for defibrillation

Introduction

In case of cardiac arrest due to ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT), the optimal energy should be the lowest energy effective to achieve defibrillation minimizing the current-induced myocardial damage. Therefore, it would be ideal to minimize the energy level as well as the number of shocks during resuscitation. ECG-based VF waveform analysis features such as amplitude spectral area have been recently introduced as predictors of shock success, but their predictivity for shock success with low energy level is not known.

Purpose

To assess whether amplitude spectral area (AMSA) of VF is able to predict the efficacy of low energy level defibrillation in out-of-hospital cardiac arrest (OHCA) patients.

Methods

All the OHCAs with at least one shockable rhythm that occurred from January 2015 to December 2020 were considered. AMSA values were calculated by retrospectively analyzing the data collected by the Corpuls 3 monitors/defibrillators and by using a 2-second-pre-shock ECG interval.

Results

Among 4619 OHCAs, resuscitation was attempted in 2982 (64%) and at least one shock was delivered in 697 (15%). AMSA values and defibrillation energy were available for 791 shocks, of which 45% received shock at low energy (&gt;150J) and 55% at high energy (&gt;150J). The rate of efficacy between the two groups was similar (44% vs 38%, p=0.102). However, in patients efficaciously treated with shock at low energy, AMSA was higher compared to those treated with shock at high energy [13.2 mV Hz (IQR 10.2–17) vs 10.8 mV Hz (IQR 8–13.8), p&lt;0.001]. Moreover, AMSA values were significantly different when comparing ineffective shock at low energy with effective shock at high energy [6.6 mV Hz (IQR 4.6–10) vs 10.8 mV Hz (IQR 8.1–13.8), p&lt;0.001] and similar when comparing ineffective shock at low and high energy [6.6 mV Hz (IQR 4.6–10) vs 6.3 mV Hz (IQR 4.5–8.7), p=0.21]. By dividing AMSA values into three tertiles, the rate of shock success at low energy was statistically different: [T1 (0.7–6.2 mV Hz) 4.2%; T2 (6.2–10.8 mV Hz) 13%; T3 (10.8–63.2 mV Hz) 42%; Chi-squared p&lt;0.001 and p for trend &lt;0.001]. After correction for age, sex, amiodarone use and call to shock time, AMSA values corresponding to the third and second tertile were associated with higher probability of shock success at low energy compared to the lowest tertile [T3 OR 15 (95% CI 7–30), p&lt;0.001; T2 OR 3 (95% CI 1–7), p=0.002].

Conclusion

Ventricular fibrillation amplitude spectral area is a predictor of shock success at a low energy level. This could be useful to optimize both time and dose-energy to patients, yielding the highest chance for successful defibrillation while reducing the number of futile shocks and thus limiting the total current myocardial energy as well as CPR interruptions.

Funding Acknowledgement

Type of funding sources: None.

Gender differences in amplitude spectral area (AMSA) of ventricular fibrillation in patients with out-of-hospital cardiac arrest

Introduction

Ventricular fibrillation (VF) Amplitude Spectral Area (AMSA) is a well-established predictor of successful defibrillation and return of spontaneous circulation (ROSC). Attending to the limited evidence on the topic, gender seems to affect AMSA, and higher values have been reported in females. The aim of this work was to investigate the effect of gender in AMSA values for patients suffering out-of-hospital cardiac arrest (OHCA).

Methods

We enrolled 4619 consecutive OHCA patients from January 2015 to December 2020 in the LombardiaCare Registry. We considered only those subjects with attempted cardio-pulmonary resuscitation (697 patients) and at least one shock delivered. A total of 250 patients were considered (40 F/ 210 M) with 830 shocks (100 F/ 730 M). AMSA values were computed for the ventricular fibrillation in the 2-s pre-shock interval of the ECG recorded by the Corpuls3 defibrillator (Corpuls, Kaufering, Germany).

Results

Female patients were older than male [median (IQR): 70.5 (62–72) vs 67 (55–75) years, p=0.01], with cardiac arrest more frequently at home (84% vs 76%, p=0.003), fewer shocks [2 (1–4) vs 4 (2–7), p=0.004] and higher percentage of success (53% vs 40%, p=0.009). On the contrary, cardiac arrest duration [ 58.7 (31–69) vs 57.6 (41.4–77.3) min, p=0.366] and the rate of ROSC (32% vs 33%, p=0.88) were similar in both groups.

Higher AMSA values were found in female patients [10.3 Hz-mV (6.6–13.5) vs 7.9 Hz-mV (5.2–12.1), p=0.0007]. At a multivariable analysis, after correction for witnessed status, bystanders CPR, amiodarone administration, age and call-to shock time, male sex was found to be independently associated with the probability of having low values of AMSA, below the median value of 8.3 Hz-mV [OR 2.15 (95% CI1.35–3.43), p=0.001].

Despite gender stratification ROC curve analysis confirmed AMSA as a predictor of shock success [AUC-F: 0.75 (95% CI 0.65–0.83), p&lt;0.001; AUC-M: 0.78 (95% CI 0.74–0.81)] and ROSC [AUC-F: 0.69 (95% CI 0.59–0.68), p=0.008; AUCM: 0.84 (95% CI 0.81–0.87)].

Conclusion

Female sex is related to higher AMSA values. As AMSA reflects the energetical status and the ATP levels in the myocardial cells during cardiac arrest, this difference may be due to lower incidence and lower severity of cardiac ischemic disease in women. AMSA remains a valid predictor of both shock success and ROSC for female and male patients. Further investigations are needed to support and comprehend these conclusions.

Funding Acknowledgement

Type of funding sources: None.

Amiodarone and ventricular fibrillation amplitude of spectral area in patients with out-of-hospital cardiac arrest. Is there an effect?

Background

The use of antiarrhythmic drug therapy is usually recommended in addition to defibrillation in shockable cardiac arrest. The role of the amplitude spectral area (AMSA) of ventricular fibrillation as a predictor of defibrillation efficacy has been established, but little is known about how amiodarone could affect AMSA values.

Purpose

The aim of our study was to evaluate whether the administration of amiodarone during resuscitation could affect AMSA and to verify if AMSA preserves its predictive role of shock success in OHCA patients treated with amiodarone.

Material

All the OHCAs with an attempted resuscitation and at least one shockable rhythm which occurred from January 2015 to December 2020 in the province of Pavia were considered. AMSA values were calculated by retrospectively analyzing the data collected by the Corpuls 3 monitors/defibrillators (Corpuls, Kaufering, Germany) used in the field and by considering a pre-shock interval of 2 seconds.

Results

Of 4619 OHCAs, 697 underwent attempted CPR with at least one shock delivered. Of these, AMSA was available on 250 patients (male 84%, median age 67 years), for a total of 830 shocks, of which 534 (64%) shocks were in patients receiving amiodarone. The success rate of each single shock was similar in the two groups (amiodarone 42% vs no amiodarone 41%, p=0.68). The AMSA median values were significantly lower in the amiodarone group as compared to the non-amiodarone group when shocks were delivered to patients older than 67 years old [median difference: 1.55 mV Hz (95% CI 0.6–2.5), p=0.0013] or receiving bystander CPR [median difference 0.9 mV Hz (95% CI 0.1–1.8), p=0.03] or after more than 33 minutes from the emergency call to each single shock [median difference: 0.91 mV Hz (95% CI 1.9–0.01), p=0.047]. AMSA value lower than the median (8.3 Hz mV) was associated with a lower probability of shock success (19% vs 64%, p&lt;0.001). According to a multivariate analysis corrected for age, sex, witnessed status, call to shock time and bystander CPR, the probability of having AMSA lower than the median was independently associated with the administration of amiodarone [OR 1.5 (95% CI 1.1–2.1) p=0.009]. At ROC curves analysis, amongst patients receiving amiodarone, AMSA was confirmed to be a predictor of both shock success and ROSC [AUC 0.755 (95% CI 0.72–0.79), p&lt;0.001 and AUC 0.826 (95% CI 0.79–0.86), p&lt;0.001 respectively], similarly to the general population [AUC 0.778 (95% CI0.75–0.81), p&lt;0.001; AUC 0.817 (95% CI 0.79–0.84), p&lt;0.001].

Conclusions

Amiodarone administration is independently associated with lower values of AMSA. This could justify the lack of benefit from amiodarone administration in term of defibrillation success which would be expected by the administration of an antiarrhythmic drug during the resuscitation. Moreover, AMSA maintains its predictive value for shock success and ROSC rate in patients receiving amiodarone as well as in the general population.

Funding Acknowledgement

Type of funding sources: None.

Anatomical-based percutaneous left stellate ganglion block in patients with refractory electrical storm: efficacy and safety

Background

The autonomic system plays a pivotal role in ventricular arrhythmogenesis. Percutaneous stellate ganglion block (PSGB) is a technique known since many years for analgesic purposes, which has recently proven its antiarrhythmic effect suitable for an emergency setting. However, evidences are limited and heterogeneous.

Purpose

To assess the efficacy and safety of PSGB performed with an anterior paratracheal approach using anatomical landmarks in consecutive patients with electrical storm refractory to conventional treatment.

Methods

Patients with electrical storm were consecutively enrolled from November 2017 to January 2022. Left PSGB (PLSGB) was performed after failure of at least one intravenous antiarrhythmic drug. Its repetition or a continuous infusion of the local anaesthetic were considered in selected cases. Clinical data, the characteristics of the block and the occurrence of complications were collected. The efficacy was evaluated by comparing the number of arrhythmias treated with ATP or DC-shocks by external or internal defibrillator in the hour before the block with that in the hour after the procedure. Per-patient efficacy was assessed by comparing the number of ATP/shocks in the 24 hours before the procedure with that in the 24 hours after the last procedure.

Results

28 patients were enrolled: 78% male, mean age 65.4±14.2 years; 9 with dilated cardiomyopathy, 8 with chronic ischemic heart disease, 7 with ST-elevation myocardial infarction, 2 with non-ST-elevation myocardial infarction, 1 with arrhythmogenic right ventricular dysplasia and 1 with drug intoxication; the average ejection fraction was 24.2±15%. A total of 44 PLSGBs were performed: 18 for ventricular tachycardia (VT), 11 for ventricular fibrillation (VF) and 15 for both VT and VF episodes; 7 on intubated patients, 3 in extracorporeal circulation, 7 in cardiogenic/septic shock, 22 on patients on single antiplatelet therapy, 7 on dual antiplatelet therapy, 25 on anticoagulant therapy. PLSGBs were performed during intravenous infusion of antiarrhythmics (amiodarone in 24, lidocaine in 27 procedures). The local anaesthetic used was lidocaine 200 mg in 16/44 PLSGB, bupivacaine 50 mg in 4/44 and both in 24/44. The per-procedure analysis showed a significant reduction of the number of ATP/shocks in the hour after PLSGB compared with the hour before [0 (0–0) vs 5 (1–8) p&lt;0.001]. Similarly, in the per-patient analysis, the number of ATP/shocks significantly decreased in the 24 hours after the PLSGB compared with that in the 24 hours before [0 (0–1.5) vs 6.5 (4.5–15.5) p&lt;0.001]. No complications occurred.

Conclusions

This is the largest case series so far in which PLSGB has proven to be highly effective and safe in the treatment of challenging patients with refractory electrical storm. Its safety and the exiguity of the equipment required for the anatomical approach make PLSGB a technique that can be easily performed by cardiologists at the bedside.

Funding Acknowledgement

Type of funding sources: None.

Impact of gender on survival of out-of-hospital cardiac arrest presenting with refractory ventricular arrhythmias and role of coronary artery disease

Funding Acknowledgements

Type of funding sources: None.

Introduction

Clinical presentation and outcome of out-of-hospital cardiac arrest (OHCA) presenting with shockable rhythm may vary between males and females. Very limited data exist on gender-related differences in OHCAs with refractory ventricular arrhythmias (VA) and, in particular, on distribution and prevalence of coronary artery disease (CAD).

Purpose

The aim of this study was to characterize gender-related outcome, prevalence and severity of CAD in OHCA victims presenting with shockable rhythm and refractory VA.

Methods

All OHCAs presenting with shockable rhythm occurred between 2015 and 2019 in the province of Pavia (Italy) and in the Canton Ticino (Switzerland) were included.

Results

Out of 3592 OHCAs, 685 presented with shockable rhythm and, of them, 212 had a refractory VA. Overall, male gender was independently associated with a lower probability of survival both at hospital admission and at 30-days (OR 0.63, 95% CI 0.58-0.67, p &lt;0.001 and OR 0.82 95% CI 0.74-0.91, p &lt;0.001, respectively) and presented with a more severe CAD. Male gender was 5-times more frequently associated with OHCA presenting with refractory VA. Despite of a more favourable OHCA presentation (i.e. more often OHCA witnessed, public place occurrence and CPR initiated by bystander) male patients with refractory VA had a lower likelihood of survival (OR 0.25, 95% CI 0.21-0.30). A higher prevalence (81%) of CAD was observed in OHCAs presenting with refractory VA but not a higher number of diseased vessels.

Conclusions

Male gender is more frequently associated with refractory VA, lower probability of survival and higher prevalence and severity of CAD. CAD severity, however, does not significantly affect refractory VA presentation.

Out-of-hospital cardiac arrest and ambient air pollution: a dose-effect relationship and a predictive role in OHCA risk

Background

Pollution has been suggested as a precipitating factor for cardiovascular diseases via a series of different mechanisms. However, data about the link between the different air pollutants and the risk of out-of-hospital cardiac arrest (OHCA) are limited and controversial.

Purpose

The primary aim of this study is to examine the impact of short-term exposure to particulate and gaseous pollutants on the incidence of OHCA in a vast metropolitan and rural area that encompasses four provinces of the Po Valley in Northern Italy, one of the most polluted areas in Italy and Europe due to its levels of industrialization and high population density. The secondary aim of this study is to look for a dose-effect curve, which could help predict OHCA incidence based on the concentration of pollutants in a specific area.

Methods

This is a retrospective analysis of prospectively collected data both in the OHCA registry (Lombardia CARe) and in the database of the regional agency for environmental protection (ARPA) of the Lombardy region. All medical OHCAs and the mean daily concentration of pollutants including fine particulate matter (PM10, PM2.5), benzene (C6H6), carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2) and ozone (O3) were considered from January 1st to December 31st, 2019 in the southern part of the Lombardy region (provinces of Pavia, Lodi, Cremona and Mantua; 7863 km2; about 155ehab724.2654 inhabitants). Days were divided into high or low incidence of OHCA according to the median daily incidence. A Probit dose-response analysis and both uni- and multivariable logistic regression models were provided for each pollutant.

Results

The median daily incidence of OHCA was 0.3 cases/100,000 inhabitants. Benzene was the pollutant with the greatest difference between days at high and low incidence of OHCA [0.7 (IQR 0.4–1.2) vs 0.4 (IQR 0.3–0.7), p&lt;0.001], whereas SO2 had the lowest and least significant difference between the two periods [3.2 (IQR 2.8–3.6) vs 3.1 (IQR 2.7–3.5), p=0.046]. O3 showed a countertrend, being significantly higher in the low-incidence period [29.9 (IQR 10.9–61.7) vs 56.1 (IQR 25.5–74.1), p&lt;0.001] as well as temperature [10.1— (IQR 5.2–14.8) vs 15.1 (IQR 8.9–23.3), p&lt;0.001]. By using the Probit regression analysis and after adjusting for temperature, a dose-response relationship was demonstrated for all the tested pollutants.

Conclusions

Our results clarify the link between pollutants and the acute risk of cardiac arrest suggesting the need of both improving the air quality and integrating pollution data in future models.

Funding Acknowledgement

Type of funding sources: None.

Amiodarone and amplitude spectral area of ventricular fibrillation in patients with out-of-hospital cardiac arrest

Background

Ventricular fibrillation is the most common cause of out-of-hospital cardiac arrest (OHCA) and the use of antiarrhythmic drug therapy is usually recommended in addition to defibrillation. The role of the amplitude spectral area (AMSA) of ventricular fibrillation as a predictor of defibrillation efficacy has been established, while the existing data in favour of the use of amiodarone has been assessed with poor evidence and controversy.

Purpose

The aim of our study is to evaluate whether the administration of amiodarone during resuscitation could affect AMSA values.

Materials

All the OHCAs with a shockable presenting rhythm and attempted resuscitation which occurred from January 2015 to June 2019 in the province of Pavia were considered. Both the end-tidal CO2 (ETCO2) and AMSA values were calculated by retrospectively analyzing the data collected by the Corpuls 3 monitors/defibrillators (Corpuls, Kaufering, Germany) used in the territory and by considering a pre-shock interval of 2 seconds.

Results

Among a total of 3413 OHCAs, resuscitation was attempted in 2195 cases (64%), 377 (17%) had a shockable presenting rhythm and in 112 cases (3.4%) it was possible to obtain the values of ETCO2 and AMSA for a total of 391 shocks. Among these, 301 shocks (77%) were delivered to patients who received amiodarone during resuscitation. The success rate of each single shock was similar in the two groups but with an unfavorable trend for amiodarone (amiodarone 43.5% vs no amiodarone 54.4%, p=0.07). AMSA was significantly lower in patients treated with amiodarone (7.9 mV·Hz, IQR 5.4–12.2 vs 10.6 mV·Hz, IQR 7.1–14.1; p&lt;0.001). According to a multivariate analysis, the administration of amiodarone and the time to shock were independent predictors of AMSA values. Lastly, on a sample of 124 shocks, homogeneous for age, sex, ETCO2, outcome of resuscitation and randomly matched, the AMSA of patients who received amiodarone was significantly lower (7.2 mV·Hz, IQR 7.2–11.7 vs 9.7 mV·Hz, IQR 6.7–12.5; p=0.02).

Conclusions

Our results indicate that amiodarone administration is associated with lower values of AMSA. Since higher AMSA values are known to be associated with a higher probability of shock rate success, this could help to better clarify the controversial role of amiodarone administration in patients with OHCA.

Funding Acknowledgement

Type of funding sources: None.