Important differences in mode of death between men and women with heart failure who would qualify for a primary prevention implantable cardioverter-defibrillator.

BACKGROUND: Whether sex differences in implantable cardioverter-defibrillator (ICD) benefit exist remains unanswered. We evaluated sex differences in mode of death among a large cohort of ambulatory heart failure patients who meet criteria for a primary prevention ICD. METHODS AND RESULTS: Patients from 5 trials or registries were included if they met American College of Cardiology/American Heart Association/Heart Rhythm Society guideline criteria for implantation of a primary prevention ICD. We investigated the potential sex differences in total deaths and total deaths by mode of death. The relationship between the estimated total mortality and mode of death by percentage of total mortality was also analyzed by sex. The Seattle Heart Failure Model was used to estimate total mortality in this analysis. A total of 8337 patients (1685 [20%] women) met inclusion criteria. One-year mortality was 10.8±0.3%. In women, the age-adjusted all-cause mortality was 24% lower (hazard ratio [HR], 0.76; confidence interval [CI], 0.68-0.85; P<0.0001), the risk of sudden death was 31% lower (HR, 0.69; CI, 0.58-0.83; P<0.0001), but no significant difference in pump failure death was observed. Throughout a range of total mortality risk, women had a 20% lower all-cause mortality (HR, 0.80; CI, 0.71-0.89; P<0.001) and 29% fewer deaths that were sudden (HR, 0.71; CI, 0.59-0.86;P<0.001) compared with men. CONCLUSIONS: Women with heart failure have a lower mortality than men, and fewer of those deaths are sudden throughout a spectrum of all-cause mortality risk. These data provide a plausible reason for and thus support the possibility that sex differences in ICD benefit may exist.

Public access defibrillation.

In the United States, 250,000 people die from a cardiac arrest every year. Despite a well established emergency medical response system, survival from out-of-hospital cardiac arrest remains poor in United States cities. Paramount to achieving successful resuscitation of a cardiac arrest victim is provision of early defibrillation. Among patients that arrest due to a ventricular fibrillation, the likelihood of survival decreases by 10% for every minute of delay in defibrillation. In 1995, the American Heart Association challenged the medical industry to develop a defibrillator that could be placed in public settings, used safely by lay responders, and provide earlier defibrillation to cardiac arrest victims. Over the last decade, there have been significant technological advancements in automated external defibrillators (AEDs), and clinical studies have demonstrated their benefits and limitations in various public locations. This article discusses the technologic features of the modern AED and the current data available on the use of AEDs in public settings.

Approach to the diagnosis and initial management of the stable adult patient with a wide complex tachycardia.

The initial electrocardiographic evaluation of every tachyarrhythmia should begin by addressing the question of whether the QRS complex is wide or narrow. The most important cause of wide complex tachycardia (WCT) is ventricular tachycardia. However, supraventricular tachycardia can also manifest with a wide QRS complex. The ability to differentiate between supraventricular tachycardia with a wide QRS due to aberrancy or preexcitation and ventricular tachycardia often presents a diagnostic challenge. The identification of whether WCT has a ventricular or supraventricular origin is critical because the treatment for each is different, and improper therapy may have potentially lethal consequences. In conclusion, although the diagnosis and treatment of sustained WCT often arise in emergency situations, this report focuses on a stepwise approach to the management of WCT in relatively stable adult patients, particularly the diagnosis and differentiation of ventricular tachycardia from supraventricular tachycardia with a wide QRS complex on standard 12-lead electrocardiography.

The automated external defibrillator.

Sudden death claims 250,000 lives annually in the U.S. The vast majority of such events are due to ventricular fibrillation and ventricular tachycardia. Even though these arrhythmias can be converted if treated promptly, less than 5% of victims of out-of-hospital cardiac arrest survive to hospitalization. This poor survival is often due to delay in the initiation of quality CPR and defibrillation. Several clinical studies have evaluated the use of an AED by nontraditional emergency medical providers and by laypersons in Public Access Defibrillation programs. These studies have demonstrated a significant improvement in survival due to earlier access to defibrillation provided by the AED. The AED has proven to be safe, reliable, and efficacious in the diagnosis and treatment of ventricular arrhythmias when employed by lay providers/rescuers in a variety of outpatient settings. Society has embraced these data and legislation has been passed that supports the implementation of PAD programs into communities and protects lay rescuers and organizations implementing these programs from liability. Concerns about cost versus benefit still serve as barriers to widespread implementation of PAD programs, but with the declining cost of AEDs and increased public awareness, many communities have initiated PAD programs. We encourage widespread implementation of PAD programs and enhanced public awareness about basic life support, with the expectation that such efforts will enhance survival of out of hospital cardiac arrest.

Differences between Korea and Japan in Physician Decision Making Regarding Permanent Pacemaker Implantation.

BACKGROUND AND OBJECTIVES: The number of permanent pacemakers (PPMs) implanted in patients in Japan and Korea differs significantly. We aimed to investigate the differences in decision making processes of implanting a PPM. MATERIALS AND METHODS: Our survey included 15 clinical case scenarios based on the 2008 AHA/ACC/HRS guidelines for device-based therapy of cardiac rhythm abnormalities (class unspecified). Members of the Korean and Japanese Societies of Cardiology were asked to rate each scenario according to a 5-point scale and to indicate their decisions for or against implantation. RESULTS: Eighty-nine Korean physicians and 192 Japanese physicians replied to the questionnaire. For the case scenarios in which there was a class I indication for PPM implantation, the decision to implant a PPM did not differ significantly between the two physician groups. However, the Japanese physicians were significantly more likely than the Korean physicians to choose implantation in class IIa scenarios (48% vs. 37%, p<0.001), class IIb scenarios (40% vs. 19%, p<0.001), and class III scenarios (36% vs. 18%, p<0.001). These results did not change when the cases were categorized based on disease entity, such as sinus node dysfunction and conduction abnormality. CONCLUSION: Korean physicians are less likely than Japanese physicians to favor a PPM implantation when considering a variety of clinical case scenarios, which probably contributes to the relatively small number of PPMs implanted in patients in Korea as compared with those in Japan.

Right bundle-branch block ventricular tachycardias: septal versus lateral ventricular origin based on activation time to the right ventricular apex.

BACKGROUND: Identifying the septal versus lateral site of origin of ventricular tachycardia (VT) with a right bundle-branch block (RBBB)-type pattern and an R-S ratio >1 in lead V1 is difficult with the 12-lead ECG, especially in patients with prior apical infarction. METHODS AND RESULTS: We prospectively evaluated 58 patients with VT. Sixteen patients had apical infarcts (group 1), 29 had nonapical infarcts (group 2), and 13 had no heart disease (group 3). QRS complex onset to activation at the right ventricular apex (stim-RVA) was measured during left ventricular (LV) apical septal and lateral pacing, and 47 RBBB-type VTs (QRS-RVA) were localized to the septal or lateral apex by using entrainment techniques. Pacing and VT site of origin were confirmed by electroanatomic mapping. The stim-RVA time was 59+/-16 ms for septal versus 187+/-24 ms for lateral sites in group 1, P<0.001; 70+/-14 ms for septal versus 169+/-19 ms for lateral sites in group 2, P<0.001; and 42+/-15 ms for septal versus 86+/-16 ms for lateral sites in group 3, P<0.005. The QRS-RVA time was 50+/-13 ms for apical septal VTs versus 178+/-21 ms for lateral VTs in group 1, P<0.001; 71+/-17 ms for apical septal versus 157+/-20 ms for lateral VTs in group 2, P<0.001; and 32+/-12 ms for septal versus 71+/-16 ms for lateral VTs in group 3, P<0.01. CONCLUSIONS: The QRS-RVA differs for the VT site of origin from the LV septal versus lateral apex. These data prove useful in rapidly regionalizing the VT site of origin with a V1 R-S ratio >1, particularly in instances of an apical infarct, where surface ECG distinctions are less identifiable.

Variable clinical features and ablation of manifest nodofascicular/ventricular pathways.

BACKGROUND: Manifest nodofascicular/ventricular (NFV) pathways are rare. METHODS AND RESULTS: From 2008 to 2013, 4 cases were identified with manifest NFV pathways from 3 centers. The clinical findings and ablation sites are reported. All 4 cases presented with a wide complex tachycardia but with different QRS morphologies. Case 1 showed a left bundle branch block/superior axis, case 2 showed a right bundle branch block/inferior axis, case 3 showed a left bundle branch block/inferior axis, and case 4 showed a narrow QRS tachycardia and a wide complex tachycardia with a left bundle branch block/inferior axis. Three of the 4 tachycardias had atrioventricular dissociation ruling out extranodal accessory pathways, including atriofascicular pathways. Programmed extrastimuli showed evidence of a decremental accessory pathway in 3 of the 4 cases. Coexisting tachycardia mechanisms were seen in 3 of the 4 cases (atrioventricular nodal reentry tachycardia [2] and atrioventricular reentrant tachycardia [1]). Ablation in the slow pathway region eliminated the NFV pathway in 3 (transient in 1) with the other responding to surgical closure of a large atrial septal defect. The NFV pathway was a critical part of the tachycardia circuit in 1 and proved to be a bystander in the other 3 cases. CONCLUSIONS: Manifest NFV pathways presented with variable QRS expression dependent on the ventricular insertion site and often coexisted with other tachycardia mechanisms (atrioventricular nodal reentry tachycardia and atrioventricular reentrant tachycardia). In most cases, the atrial insertion of the pathway was in or near the slow pathway region. The NFV pathways were either critical to the tachycardia circuit or served as bystanders.

Change in distant atrial activation patterns during circumferential pacemapping of pulmonic vein ostium: implications for localizing triggers for atrial fibrillation.

INTRODUCTION: Unique intracardiac activation patterns recorded from multipolar catheters in the coronary sinus (CS) and posteromedial right atrium (RA) when pacing from ostium (os) of each pulmonic vein (PV) can serve as template for determining PV of origin of atrial premature complexes. Development of an accurate template requires knowledge of variations in activation pattern during pacing from different aspects of same PV. METHODS: In 25 patients undergoing catheter ablation for AF, a decapolar Lasso mapping catheter was placed at PV os of interest and multipolar catheters were placed in CS and RA-medial to crista terminalis (CT). For each PV, pacing was performed from Lasso catheter poles 1 through 10. For each bipole paced, activation sequence in CS (proximal to distal & vice-versa) was assessed, activation time (pacing stimulus to earliest electrogram recorded in catheters in CS/along CT) was measured and difference (CS - CT time) was determined. Significant interpolar variation was defined as the difference between the shortest and longest CS - CT activation time of >/=25 msec when pacing from different bipoles of same PV. RESULTS: In 59 PVs [19 right superior (RS), 20 left superior (LS), 8 right inferior (RI) and 12 left inferior (LI)], 259 bipoles were paced (median of 4 bipoles/PV). During circumferential PV pacing activation sequence in CS catheter was distal to proximal in 84.4% left-sided PVs (LSPV and LIPV) and proximal to distal in 92.6% right-sided PVs (RSPV and RIPV) with no change in activation sequence observed during pacing from different bipoles in same PV. Significant interpolar variation was observed with circumferential pacing in 1 of 19 RSPV (5.3%), 2 of 20 LSPV (10%), 1 of 12 LIPV (8.3%) and none of RIPV. CONCLUSION: Unique intracardiac activation patterns during ostial pacing from individual PV are not influenced by circumferential location of pacing site.

Public Access Defibrillation.

In the United States, 250,000 people die from a cardiac arrest every year. Despite a well established emergency medical response system, survival from out-of-hospital cardiac arrest remains poor in United States cities. Paramount to achieving successful resuscitation of a cardiac arrest victim is provision of early defibrillation. Among patients that arrest due to a ventricular fibrillation, the likelihood of survival decreases by 10% for every minute of delay in defibrillation. In 1995, the American Heart Association challenged the medical industry to develop a defibrillator that could be placed in public settings, used safely by lay responders, and provide earlier defibrillation to cardiac arrest victims. Over the last decade, there have been significant technological advancements in automated external defibrillators (AEDs), and clinical studies have demonstrated their benefits and limitations in various public locations. This article discusses the technologic features of the modern AED and the current data available on the use of AEDs in public settings.

Asymptomatic atrial fibrillation.

Atrial fibrillation (AF) is a significant cause of morbidity and health care expenditures. Patients with AF suffer a variety of symptoms including chest pain, palpitations, shortness of breath, and fatigue. Some patients have no symptoms, a condition referred to as asymptomatic or "silent" AF. Asymptomatic AF has significant clinical implications. Patients with unrecognized AF may present with devastating thromboembolic consequences or a tachycardia-mediated cardiomyopathy. The incidence of asymptomatic AF is greater than previously perceived. This manuscript provides an overview of the clinical entity of asymptomatic AF including the epidemiology, clinical significance, and the implications it has on the daily management of patients suffering from AF.

Biphasic versus monophasic shock waveform for conversion of atrial fibrillation.

Cardioversion of atrial fibrillation (AF) using traditional monophasic shock waveform is unsuccessful in up to 20% of cases, and often requires several shocks of up to 360 J. Based on the success with biphasic shock waveform in converting ventricular fibrillation, it was postulated that biphasic shocks would allow cardioversion with lower energy. In a international multicenter, double-blind, randomized trial of 203 patients, damped sine wave monophasic shocks were compared with impedance-compensated truncated exponential biphasic waveform shocks. Patients received up to five shocks: 100 J, 150 J, 200 J, a fourth shock at maximum output for the initial waveform (200 J biphasic, 360 J monophasic) and a final cross-over shock at maximum output of the alternate waveform. For each energy level, the biphasic waveform compared favorably to the monophasic waveform in successful cardioversion (100 J: 60% versus 22%, P < 0.0001; 150 J: 77% versus 44%, p < 0.0001; 200 J: 90% versus 53%, p < 0.0001). Success with 200 J biphasic was equivalent to 360 J monophasic shock (91% versus 85%, p = 0.29). Patients randomized to biphasic waveform required fewer shocks and lower total energy delivered; in addition, this waveform was associated with less dermal injury and no blistering. Biphasic shocks converted AF present for less than 48 hours with 80% efficacy, but conversion of AF present for more than 48 hours and more than 1 year the success rate was only 63 and 20%, respectively. The results of this study is similar to other investigations comparing biphasic and monophasic shock waveforms for conversion of atrial fibrillation. We recommend starting with biphasic energy of 100 J for atrial fibrillation of less than 48 hours duration, but using higher energies (150 J, 200 J or greater) when AF has been present for longer periods.

Elevations in ventricular pacing threshold with the use of the Y adaptor: implications for biventricular pacing.

Cardiac resynchronization therapy (CRT) is a new and promising therapeutic option for patients with severe heart failure and intraventricular conduction delay. Patients who are candidates for CRT and have a previously implanted device may utilize a "Y" IS 1 connector to accommodate the coronary sinus lead. This modification has the potential to alter biventricular pacing thresholds. During an 18 month period, successful biventricular pacemaker implantation was performed in 72 patients (age: 67 +/- 11 years, left ventricular ejection fraction: 20.5 +/- 5.6%). All of these patients had severe symptomatic congestive heart failure (NYHA Class III and IV). In 20 patients a special "Y" adaptor that bifurcates the ventricular IS 1 bipolar output to two bipolar outputs or one unipolar and one bipolar output was utilized. During initial implantation, LV thresholds obtained in a unipolar configuration prior to connecting to the "Y" adaptor were significantly lower than thresholds obtained after connecting to the "Y" adaptor (1.7 +/- 1.11 V at 0.5 ms pulse width versus 2.8 +/- 1.5 V at 0.5 ms pulse width [P = 0.01]). Two patients (10%) required left ventricular lead revisions due to unacceptably high left ventricular thresholds during device follow-up. The difference in measured left ventricular thresholds between the two configurations is best explained by a resistive element that is added to the circuit when performing threshold measurement of the LV lead through the "Y" adaptor (combined tip to RV ring configuration) versus measurement of the LV lead in a unipolar configuration. This resistive element represents multiple factors including anode surface area, resistive polarization at the tissue-electrode interface, and transmyocardial resistance. LV thresholds should be measured in an LV tip to RV ring configuration or ideally in a combined tip (LV and RV) to shared ring configuration in order to accurately assess LV thresholds. This observation has significant clinical implications as loss of capture may occur as a result of improper measurement of left ventricular thresholds at the time of implantation.