Validation of a novel smartphone-based photoplethysmographic method for ambulatory heart rhythm diagnostics

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Vinnova - The Swedish Agency for Innovation Systems.

Region Stockholm Innovation Fund.

Introduction

Devices for long-term and ambulatory recording of heart rhythm have limited availability within health care systems worldwide, potentially leading to missed diagnoses and limitations in peri-procedural heart rhythm management. As smartphones are becoming ubiquitous the availability of heart rhythm diagnostics and management of atrial fibrillation (AF) using smartphone photoplethysmography (PPG) compared to electrocardiography (ECG) is increasing. Previous validation studies of smartphone-PPG applications have all been performed under supervision in healthcare settings. In addition, no previous study has validated smartphone-PPG compared to simultaneous ECG recordings, with manual heart rhythm interpretation of the PPG recordings nor have they included patients with atrial flutter (AFL).

Purpose

The aim of this study was to validate a novel smartphone-PPG method for heart rhythm diagnostics in patients with AF and/or AFL when in use unsupervised in an ambulatory setting.

Methods

Unselected patients undergoing direct current cardioversion at a University Hospital for treatment of AF or AFL were asked to perform one-minute heart rhythm recordings post-treatment at least twice daily for 30 days in their home environment. All included were provided with an unmodified iPhone 7 smartphone running the CORAI Heart Monitor PPG application simultaneously with a single-lead ECG recording (KardiaMobile). PPG and ECG recordings were interpreted independently by two readers.

Results

In total 280 patients, with median age of 69.0 years (31% women) were included from November 2018 to July 2020 and registered 18 005 simultaneous PPG and ECG recordings. Of the PPG recordings 96.9% had sufficient quality for diagnosis compared to 95.1% of the ECG recordings (p < 0.001). Precardioversion ECG recordings were interpreted as AF in 82.1%, AFL in 14.3% and as having insufficient quality for diagnosis in 3.6% of the patients. After removal of recordings with insufficient quality 69.7% of ECG recordings were interpreted as sinus rhythm, 28.2% as AF and 2.1 % as AFL. Manual interpretation of the PPG recordings diagnosed AF/AFL (sensitivity) in 97.7% and sinus rhythm (specificity) in 99.4% of the recordings compared to manually interpreted ECG recordings, with an overall accuracy of 98.9%. Results excluding recordings interpreted as AFL on ECG or PPG diagnosed AF (sensitivity) in 99.0% and sinus rhythm (specificity) in 99.7% of the recordings, with an overall accuracy of 99.5%.

Conclusion

A novel smartphone-PPG method can be used by patients unsupervised in their home environment for accurate heart rhythm diagnostics of AF and AFL with high sensitivity and specificity.

Prevalence of silent atrial fibrillation in high-risk patients - preliminary results from a European three-country handheld ECG-screening study

Funding Acknowledgements

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Helsefonden Lilly and Herbert Hansens Foundation

Introduction

Patients with atrial fibrillation (AF) should in most cases be offered prophylactic anticoagulation treatment to prevent a stroke. However, the arrhythmia can appear without symptoms, so-called silent AF. Even without symptoms AF constitutes a risk for stroke.

Purpose

To screen high-risk patients with diabetes type 2 (DMII) or heart failure (CHF) for silent AF.

Methods

We included patients > 64 years with either DMII or CHF from out-patient clinics and local health centers. Exclusion criteria were known AF, anticoagulation treatment, recent stroke, or an implanted pacemaker or ICD. Patients were recruited from a total of eleven study centers in three countries. All underwent 14-days of intermittent ECG screening with a handheld ECG recording four times each day; the recordings were digitally stored. AF was diagnosed in cases of irregular heart rhythm and absence of P waves on at least one recording (thirty seconds) or on at least two recordings for a minimum of ten seconds.

Results

In total, 813 patients were included, 541 of these with DMII. The mean age was 73,4 years ± 5,8 SD, 40,7% of the patients were female.

In the DMII group thirteen patients (2.4%) were diagnosed with silent AF and offered anticoagulation. In the CHF group six (2.2%) patients had diagnosed silent AF on the handheld ECG. The prevalence of AF increased with increasing age, see Table 1. Thus, in the youngest group AF was diagnosed in 1.3% of the patients compared to 3.9 % in the age group 75 years or older.

Conclusions

Screening for silent AF in high-risk patients with DMII or CHF seems worthwhile, especially in patients 75 years or older. Abstract Figure. ECG with atrial fibrillation

Large-scale screening studies for atrial fibrillation - is it worth the effort?

Atrial fibrillation (AF) is a common disease with increasing prevalence, approximately 3.2% in the adult population. In addition, about one third of AF cases are considered asymptomatic. Due to increased longevity, increased detection and increased prevalence of risk factors, the prevalence of AF is expected to at least double by the year 2060. Patients with AF have an increased risk for ischaemic stroke, heart failure, death and cognitive decline. Treatment with oral anticoagulation reduces the risk of ischaemic stroke and mortality, and the effect on cognitive decline is being studied. Based on the increasing prevalence of AF, its often asymptomatic and paroxysmal presentation and the efficacy of oral anticoagulation treatment, screening for AF has been proposed. AF seems to fulfil most of the Wilson-Jungner criteria for screening issued by the World Health Organization, but some knowledge gaps remain, gaps that will be addressed by several ongoing studies. The knowledge gaps in AF screening consist of the magnitude of the net benefit or net harm inflicted by AF screening because the oral anticoagulation treatment will also increase the risk of bleeding, and the psychological effects of AF screening are not very well studied. So far, the AF screening recommendations issued by the European Society of Cardiology have had limited impact on national and regional AF screening activities. Several large-scale AF screening studies will report results on hard endpoints within the next few years, and these results will hopefully manifest AF as a cardiovascular disease which we need to pay more attention to.

P6538Validity of two weeks daily self pulse-palpation for opportunistic screening for atrial fibrillation among patients 65 years and older

Background

Pulse-palpation is recommended (ESC IA) for single time-point screening for atrial fibrillation (AF). AF may, however, be paroxysmal which can make AF detection difficult to detect on single time-point measurement. Intermittent ECG recording is a sensitive method to detect AF. However, the role of pulse-palpation for AF detection has not been validated against simultaneous ECG recordings.

Purpose

To study the validity of AF detection using self pulse-palpation simultaneously with hand-hold ECG recording 3 times daily for two weeks for AF.

Method

Patients 65 years and older visiting four primary health care centers, four any reason, were invited to AF screening from July 2017 to December 2018. Hand-held intermittent ECG recordings, 30 seconds three times a day, was offered to participants without AF for a period of 2 weeks. Patients were instructed how to take their own pulse, simultaneously with intermittent ECG measurement and in written to note whether it was irregular or not.

Results

A total of 1010 patients (mean age 73 years, 61% women) participated in the study, 27 new cases of AF (mostly paroxysmal) were detected. Totally 53 782 simultaneous ECG-recordings and pulse-measurements were registered. AF was verified in 311 ECG-recordings but the pulse was palpated as irregular only in 77 of these recordings (25% sensitivity per measurement-occasion). Of those 27 detected AF cases, 15 cases felt their pulse as irregular at least at once occasion (56% sensitivity per individuals). 187 individuals without AF felt their pulse as irregular in at least one occasion. The specificity per measurement-occasion and per individuals were 98% and 81% respectively. Diagnostic odds ratio was 5.3.

AF 27 patients No AF 983 patients Irregular pulse 202 individuals 15 187 Regular pulse 808 individuals 12 796 Sensitivity 56% Specificity 81% Positive Predictive Value 7% Negative Predictive Value 99% AF 311 measurements No AF 53471 measurements Irregular pulse 1046 measurements 77 969 Regular pulse 52,736 measurements 234 52,502 Sensitivity 25% Specificity 98% Positive Predictive Value 7% Negative Predictive Value 99%

Conclusion

AF screening using own pulse-palpation 3 times daily for two weeks is feasible but has a low sensitivity for AF detection.

Acknowledgement/Funding

This study was supported by the Swedish Heart and Lung Foundation, Pfizer, Boehringer-Ingelheim and Bayer

The challenges and possibilities of public access defibrillation

Out-of-hospital cardiac arrest (OHCA) is a major health problem that affects approximately four hundred and thousand patients annually in the United States alone. It is a major challenge for the emergency medical system as decreased survival rates are directly proportional to the time delay from collapse to defibrillation. Historically, defibrillation has only been performed by physicians and in-hospital. With the development of automated external defibrillators (AEDs), rapid defibrillation by nonmedical professionals and subsequently by trained or untrained lay bystanders has become possible. Much hope has been put to the concept of Public Access Defibrillation with a massive dissemination of public available AEDs throughout most Western countries. Accordingly, current guidelines recommend that AEDs should be deployed in places with a high likelihood of OHCA. Despite these efforts, AED use is in most settings anecdotal with little effect on overall OHCA survival. The major reasons for low use of public AEDs are that most OHCAs take place outside high incidence sites of cardiac arrest and that most OHCAs take place in residential settings, currently defined as not suitable for Public Access Defibrillation. However, the use of new technology for identification and recruitment of lay bystanders and nearby AEDs to the scene of the cardiac arrest as well as new methods for strategic AED placement redefines and challenges the current concept and definitions of Public Access Defibrillation. Existing evidence of Public Access Defibrillation and knowledge gaps and future directions to improve outcomes for OHCA are discussed. In addition, a new definition of the different levels of Public Access Defibrillation is offered as well as new strategies for increasing AED use in the society.

All-cause and cardiovascular mortality risk after surgery versus radioiodine treatment for hyperthyroidism

Background

Little is known about the long-term side-effects of different treatments for hyperthyroidism. The few studies previously published on the subject either included only women or focused mainly on cancer outcomes. This register study compared the impact of surgery versus radioiodine on all-cause and cause-specific mortality in a cohort of men and women.

Methods

Healthcare registers were used to find hyperthyroid patients over 35 years of age who were treated with radioiodine or surgery between 1976 and 2000. Comparisons between treatments were made to assess all-cause and cause-specific deaths to 2013. Three different statistical methods were applied: Cox regression, propensity score matching and inverse probability weighting.

Results

Of the 10 992 patients included, 10 250 had been treated with radioiodine (mean age 65·1 years; 8668 women, 84·6 per cent) and 742 had been treated surgically (mean age 44·1 years; 633 women, 85·3 per cent). Mean duration of follow-up varied between 16·3 and 22·3 years, depending on the statistical method used. All-cause mortality was significantly lower among surgically treated patients, with a hazard ratio of 0·82 in the regression analysis, 0·80 in propensity score matching and 0·85 in inverse probability weighting. This was due mainly to lower cardiovascular mortality in the surgical group. Men in particular seemed to benefit from surgery compared with radioiodine treatment.

Conclusion

Compared with treatment with radioiodine, surgery for hyperthyroidism is associated with a lower risk of all-cause and cardiovascular mortality in the long term. This finding was more evident among men.

Drones may be used to save lives in out of hospital cardiac arrest due to drowning

BACKGROUND

Drowning leading to out-of-hospital cardiac arrest (OHCA) and death is a major public health concern. Submersion with duration of less than 10min is associated with favorable neurological outcome and nearby bystanders play a considerable role in rescue and resuscitation. Drones can provide a visual overview of an accident scene, their potential as lifesaving tools in drowning has not been evaluated.

AIM

The aim of this simulation study was to evaluate the efficiency of a drone for providing earlier location of a submerged possible drowning victim in comparison with standard procedure.

METHOD

This randomized simulation study used a submerged manikin placed in a shallow (<2m) 100×100-m area at Tylösand beach, Sweden. A search party of 14 surf-lifeguards (control) was compared to a drone transmitting video to a tablet (intervention). Time from start to contact with the manikin was the primary endpoint.

RESULTS

Twenty searches were performed in total, 10 for each group. The median time from start to contact with the manikin was 4:34min (IQR 2:56-7:48) for the search party (control) and 0:47min (IQR 0:38-0:58) for the drone-system (intervention) respectively (p<0.001). The median time saved by using the drone was 3:38min (IQR 2:02-6:38).

CONCLUSION

A drone transmitting live video to a tablet is feasible, time saving in comparison to traditional search parties and may be used for providing earlier location of submerged victims at a beach. Drone search can possibly contribute to earlier onset of CPR in drowning victims.

Unmanned aerial vehicles (drones) in out-of-hospital-cardiac-arrest

Background

The use of an automated external defibrillator (AED) prior to EMS arrival can increase 30-day survival in out-of-hospital cardiac arrest (OHCA) significantly. Drones or unmanned aerial vehicles (UAV) can fly with high velocity and potentially transport devices such as AEDs to the site of OHCAs. The aim of this explorative study was to investigate the feasibility of a drone system in decreasing response time and delivering an AED.

Methods

Data of Global Positioning System (GPS) coordinates from historical OHCA in Stockholm County was used in a model using a Geographic Information System (GIS) to find suitable placements and visualize response times for the use of an AED equipped drone. Two different geographical models, urban and rural, were calculated using a multi-criteria evaluation (MCE) model. Test-flights with an AED were performed on these locations in rural areas.

Results

In total, based on 3,165 retrospective OHCAs in Stockholm County between 2006–2013, twenty locations were identified for the potential placement of a drone.

In a GIS-simulated model of urban OHCA, the drone arrived before EMS in 32 % of cases, and the mean amount of time saved was 1.5 min. In rural OHCA the drone arrived before EMS in 93 % of cases with a mean amount of time saved of 19 min. In these rural locations during (n = 13) test flights, latch-release of the AED from low altitude (3–4 m) or landing the drone on flat ground were the safest ways to deliver an AED to the bystander and were superior to parachute release.

Discussion

The difference in response time for EMS between urban and rural areas is substantial, as is the possible amount of time saved using this UAV-system. However, yet another technical device needs to fit into the chain of survival. We know nothing of how productive or even counterproductive this system might be in clinical reality.

Conclusions

To use drones in rural areas to deliver an AED in OHCA may be safe and feasible. Suitable placement of drone systems can be designed by using GIS models. The use of an AED equipped drone may have the potential to reduce time to defibrillation in OHCA.

Out-of-hospital cardiac arrest: 10 years of progress in research and treatment

Cardiac disease is the most common cause of mortality in Western countries, with most deaths due to out-of-hospital cardiac arrest (OHCA). In Sweden, 5000-10 000 OHCAs occur annually. During the last decade, the time from cardiac arrest to start of cardiopulmonary resuscitation (CPR) and defibrillation has increased, whereas survival has remained unchanged or even increased. Resuscitation of OHCA patients is based on the 'chain-of-survival' concept, including early (i) access, (ii) CPR, (iii) defibrillation, (iv) advanced cardiac life support and (v) post-resuscitation care. Regarding early access, agonal breathing, telephone-guided CPR and the use of 'track and trigger systems' to detect deterioration in patients' condition prior to an arrest are all important. The use of compression-only CPR by bystanders as an alternative to standard CPR in OHCA has been debated. Based on recent findings, guidelines recommend telephone-guided chest compression-only CPR for untrained rescuers, but trained personnel are still advised to give standard CPR with both compressions and ventilation, and the method of choice for this large group remains unclear and demands for a randomized study. Data have shown the benefit of public access defibrillation for dispatched rescuers (e.g. police and fire fighters) but data are not as strong for the use of automated defibrillators (AEDs) by trained or untrained rescuers. Postresuscitation, use of therapeutic hypothermia, the importance of specific prognostic survival factors in the intensive care unit and the widespread use of percutaneous coronary intervention have all been considered. Despite progress in research and improved treatment regimens, most patients do not survive OHCA. Particular areas of interest for improving survival include (i) identification of high-risk patients prior to their arrest (e.g. early warning symptoms and genes); (ii) increased use of bystander CPR training (e.g. in schools) and simplified CPR techniques; (iii) better identification of high-incidence sites and better recruitment of AEDs (via mobile phone solutions?); (iv) improved understanding of the use of therapeutic hypothermia; (v) determining which patients should undergo immediate coronary angiography on hospital admission; and (vi) clarifying the importance of extracorporeal membrane oxygenation during CPR.

The safety of flecainide treatment of atrial fibrillation: long-term incidence of sudden cardiac death and proarrhythmic events

OBJECTIVE

To assess the safety of long-term treatment with flecainide in patients with atrial fibrillation (AF), particularly with regard to sudden cardiac death (SCD) and proarrhythmic events.

DESIGN

Retrospective, observational cohort study.

SETTING

Single-centre study at Örebro University Hospital, Sweden. Subjects.  A total of 112 patients with paroxysmal (51%) or persistent (49%) AF (mean age 60 ± 11 years) were included after identifying all patients with AF who initiated oral flecainide treatment (mean dose 203 ± 43 mg per day) between 1998 and 2006. Standard exclusion/inclusion criteria for flecainide were used, and flecainide treatment was usually combined with an atrioventricular-blocking agent (89%).

MAIN OUTCOME MEASURE

Death was classified as sudden or nonsudden according to standard definitions. Proarrhythmia was defined as cardiac syncope or life-threatening arrhythmia.

RESULTS

Eight deaths were reported during a mean follow-up of 3.4 ± 2.4 years. Compared to the general population, the standardized mortality ratios were 1.57 (95% confidence interval (CI) 0.68-3.09) for all-cause mortality and 4.16 (95% CI 1.53-9.06) for death from cardiovascular disease. Three deaths were classified as SCDs. Proarrhythmic events occurred in six patients (two each with wide QRS tachycardia, 1 : 1 conducted atrial flutter and syncope during exercise).

CONCLUSION

We found an increased incidence of SCD or proarrhythmic events in this real-world study of flecainide used for the treatment of AF. The findings suggest that further investigation into the safety of flecainide for the treatment of patients with AF is warranted.

Digoxin in atrial fibrillation: report from the Stockholm Cohort study of Atrial Fibrillation (SCAF)

BACKGROUND

Recent studies of patients with heart failure and of patients receiving intensive care indicate that digoxin may increase mortality if the patient has atrial fibrillation (AF). Objective To study which patients receive digoxin treatment for AF and what the prognosis is for patients given this treatment.

METHOD

2824 patients with AF were studied prospectively for a mean of 4.6 years. Information about medication was obtained from the local hospital registry. Information about diagnoses, hospitalisations and deaths was obtained from national registries. Propensity score matching and Cox regression was used to account for confounding.

RESULTS

Factors associated with digoxin use were permanent AF (hazard ratio (HR) = 3.2, confidence interval (CI) 2.7 to 3.9), absence of pacemaker (HR = 2.3, CI 1.6 to 3.2), history of heart failure (HR = 2.0, CI 1.7 to 2.5), treatment in an internal medicine ward rather than a cardiology ward (HR = 1.6, CI 1.3 to 2.0), female sex (HR = 1.6, CI 1.3 to 1.9) and age >or=80 years (HR = 1.4, CI 1.1 to 1.7). More patients with than without digoxin died (51% vs 31%, p<0.001). After adjustment for covariates, however, no disadvantages related to digoxin use could be found for all-cause mortality, myocardial infarction, ischaemic stroke, time to readmission to hospital or days at hospital/year at risk. The only end point significantly associated with digoxin use was pacemaker implantations, which were more common in digoxin-treated patients (HR = 2.0, CI 1.2 to 3.4).

CONCLUSION

Digoxin is mainly given to an elderly and frailer subset of patients with AF and is thus associated with an increased mortality. When differences in patient characteristics are accounted for digoxin use seems to have a neutral effect on mortality and major cardiovascular events in patients with AF.

Atrial arrhythmias--the dominating cardiac problem in three patients with HLA B27 associated rheumatic disorders

Three young patients with atrial arrhythmias as the probable consequence of an HLA B27 associated inflammatory disease process are described. They are presented as an expansion of the spectrum of cardiac manifestations that can be seen in patients with HLA B27 associated rheumatic disorders, and as possible evidence of myocardial involvement of this disease process.

Aspects on the increase in bystander CPR in Sweden and its association with outcome

AIM

To describe changes in the proportion of bystanders performing cardiopulmonary resuscitation (CPR) in out of hospital cardiac arrest (OHCA) in Sweden and to study the impact of bystander CPR on ventricular fibrillation and on survival during various times.

PATIENTS AND METHODS

All patients who suffered from OHCA in Sweden in whom CPR was attempted and who were included in the Swedish cardiac arrest register (SCAR) between 1992 and 2005. Crew witnessed cases were excluded.

RESULTS

In all 34,125 patients were included in the survey. Among witnessed OHCA the proportion of patients receiving bystander CPR increased from 40% in 1992 to 55% in 2005 (p<0.0001). In non-witnessed OHCA the corresponding proportion increased from 22% to 44% (p<0.0001). There was a significant increase in bystander CPR regardless of age, sex and place. The increase was only found when CPR was performed by lay persons (21% in 1992 to 40% in 2005; p<0.0001). Bystander CPR was associated with an increased proportion of patients found in a shockable rhythm and a lower number of shocks to receive return of spontaneous circulation. Bystander CPR was associated with a similar increase in survival early and late in the evaluation.

CONCLUSION

There was a marked increase in bystander CPR in OHCA, when performed by lay persons, during the last 14 years in Sweden. Bystander CPR was associated with positive effects both on ventricular fibrillation and survival.

An evaluation of post-resuscitation care as a possible explanation of a difference in survival after out-of-hospital cardiac arrest

BACKGROUND

A recently published study has shown that survival after out-of-hospital cardiac arrest (OHCA) in Göteborg is almost three times higher than in Stockholm. The aim of this study was to investigate whether in-hospital factors were associated with outcome in terms of survival.

METHODS

All patients suffering from OHCA in Stockholm and Göteborg between January 1, 2000 and June 30, 2002 were included. The two groups were compared with reference to patient characteristics, medical history, pre-hospital and hospital course (including in-hospital investigations and interventions) and mortality. All medical charts from patients admitted alive to the different hospitals were studied. Data from the Swedish National Register of Deaths regarding long-term survival were analysed. Pre-hospital data were collected from the Swedish Ambulance Cardiac Arrest Register.

RESULTS

In all, 1542 OHCA in Stockholm and 546 in Göteborg were registered during the 30-month study period. In Göteborg, 28% (153 patients) were admitted alive to the two major hospitals whereas in Stockholm 16% (253 patients) were admitted alive to the seven major hospitals (p<0.0001). On admission to the emergency rooms, a larger proportion of patients in Stockholm was unconscious (p=0.006), received assisted breathing (p=0.008) and ongoing CPR (p=0.0002). Patient demography, medical history, in-hospital investigations and interventions and in-hospital mortality (78% in Göteborg, 80% in Stockholm) did not differ between the two groups. Various pre-hospital time intervals were significantly longer in Stockholm than in Göteborg. Total survival to discharge after OHCA was 3.3% in Stockholm and 6.1% in Göteborg (p=0.01).

CONCLUSION

An almost 2-fold difference in survival after OHCA between Stockholm and Göteborg appears to be associated with pre-hospital factors only (predominantly in form of prolonged intervals in Stockholm), rather than with in-hospital factors or patient characteristics.

Long-term prognosis in patients with bifascicular block--the predictive value of noninvasive and invasive assessment

OBJECTIVES

Patients with bifascicular block (BFB) have a high mortality rate. The purpose of the present study was to identify high-risk patients in a BFB population by performing an extensive cardiac evaluation including noninvasive and invasive tests.

DESIGN

Population-based study.

SUBJECTS

A total of 100 patients with BFB, of whom 41 had a history of unexplained syncope, were prospectively studied. The mean age was 68 +/- 12. All patients were investigated with Holter-monitoring, an exercise test, an echocardiography, and an invasive electrophysiological study. The severity of congestive heart failure (CHF) was assessed by New York Heart Association (NYHA) classification. Patients in NYHA class IV were excluded.

INTERVENTIONS

Patients with syncope were recommended prophylactic pacemaker treatment, which was accepted by 31 patients (76%). Main outcome measures. All-cause mortality and sudden cardiac death (SCD).

RESULTS

During a median follow-up of 84 months, 33 patients died, of whom 14 in SCD. In a univariate analysis, high age, a previous myocardial infarction, and CHF were associated with a significantly increased risk of all-cause mortality and SCD. In a Cox multiple regression analysis, CHF was the only independent predictor of all-cause mortality and SCD (P < 0.01).

CONCLUSION

Patients with BFB have a poor long-term prognosis. The predictive value of noninvasive and invasive investigations is limited. The only independent predictor of all-cause mortality and SCD in this population was the presence of CHF.

Difference in survival after out-of-hospital cardiac arrest between the two largest cities in Sweden: a matter of time?

BACKGROUND

Dramatic differences in survival after out-of-hospital cardiac arrests (OHCA) reported from different geographical locations require analysis. We therefore compared patients with OHCA in the two largest cities in Sweden with regard to various factors at resuscitation and outcome.

SETTING

All patients suffering an OHCA in Stockholm and Goteborg between 1 January 2000 and 30 June 2001, in whom cardiopulmonary resuscitation (CPR) was attempted were included in this retrospective analysis.

RESULTS

All together, 969 OHCA in Stockholm and 398 in Goteborg were registered during the 18-month study period. There were no differences in terms of age, gender, and percentage of witnessed cases or percentage of patients who had received bystander CPR. However, the percentage of patients with ventricular fibrillation (VF) at arrival of the ambulance crew was 18% in Stockholm versus 31% in Goteborg (P <0.0001). The percentage of patients who were alive 1 month after cardiac arrest was 2.5% in Stockholm versus 6.8% in Goteborg (P=0.0008). Various time intervals such as cardiac arrest to calling for an ambulance, cardiac arrest to the start of CPR and calling for an ambulance to its arrival were all significantly longer in Stockholm than in Goteborg.

CONCLUSION

Survival was almost three times higher in Goteborg than in Stockholm amongst patients suffering an OHCA. This is primarily explained by a higher occurrence of VF at the time of arrival of the ambulance crew, which in turn probably is explained by shorter delays in Goteborg. The reason for the difference in time intervals is most likely multifactorial, with a significantly higher ambulance density in Goteborg as one possible explanation.

Duration of warfarin sodium therapy prior to electrical cardioversion of atrial fibrillation

OBJECTIVES

To evaluate the duration of anticoagulation treatment with warfarin sodium before elective DC-cardioversion and to identify clinical variables predicting short-term versus long-term waiting times.

DESIGN

Retrospective.

SUBJECTS

Patients with a known start date for warfarin sodium, a known duration of atrial fibrillation (AF) and who underwent DC-cardioversion were included.

MAIN OUTCOME MEASURES

Duration of treatment with warfarin sodium prior to DC-cardioversion.

METHODS

The hospital records of 288 consecutive patients with AF scheduled for elective cardioversion at two hospitals in Stockholm were reviewed. Only patients with a known start date for warfarin sodium and known duration of AF were included in the study.

RESULTS

The median age was 70 (26-85) years and the duration of AF at time of cardioversion were 18 weeks (5-273) weeks. The median treatment duration prior to cardioversion with warfarin sodium was 12 weeks. Sinus rhythm was established in 224 (78%) patients of which 90 (40%) remained in sinus rhythm 1 month after cardioversion. In multivariate analysis, the only independent predictor of short waiting times for cardioversion (8 vs. 15 weeks) was if a cardiologist instituted the treatment with warfarin sodium (P < 0.001, 95% CI 5.0-9.0).

CONCLUSION

The average waiting time from start of warfarin sodium treatment to elective cardioversion exceeds by far the recommended 3-4 weeks on therapeutic international normalized ratio (INR). In order to minimize the time period until cardioversion significant changes in the out-of-hospital care logistics has to be undertaken.

Asymptomatic versus symptomatic persistent atrial fibrillation: clinical and noninvasive characteristics

OBJECTIVE

This prospective study was designed to investigate the differences between asymptomatic versus symptomatic arrhythmia as well as left ventricular dysfunction in a consecutive population of patients with persistent atrial fibrillation.

DESIGN

A total of 282 consecutive outpatients referred with persistent atrial fibrillation formed the study population. A structured medical history was obtained. A two-dimensional transthoracic echocardiography to assess the left ventricular function and a 24-h electrocardiogram (ECG) recording were performed. Irregularity of the heart rhythm was analysed with heart rate variability (HRV) in the time domain as well as maximum and minimum heart rate and the longest pause.

SETTING

Three university hospitals.

RESULTS

The mean age of the patients was 69 years and the mean duration of atrial fibrillation was 7 months. The prevalence of symptomatic patients was 68%, while 32% had no symptoms from atrial fibrillation, left ventricular dysfunction was observed in 20%. Asymptomatic subjects had more often lone atrial fibrillation than those with symptoms. Valvular heart disease was an independent predictor of symptoms while male gender, ischaemic heart disease and a high heart rate were independent predictors of impaired left ventricular function.

CONCLUSION

Valvular heart disease is related to symptoms in persistent atrial fibrillation. Ischaemic heart disease, male gender and a high heart rate are more common in patients with impaired left ventricular function. Compromised left ventricular function does, occur also in asymptomatic subjects underlining the importance of a careful investigation including echocardiography in all subjects with persistent atrial fibrillation.