[Successful hybrid therapy combined with oral bepridil and ICD in a patient with amiodarone refractory life-threatening ventricular tachyarrhythmia associated with ischemic cardiomyopathy]

A 68-year-old man was admitted to our hospital for the treatment of angina and ventricular tachyarrhythmia. A coronary and left ventricular angiography showed coronary artery disease and ischemic cardiomyopathy with severe left ventricular dysfunction. A percutaneous transluminal coronary angioplasty was performed successfully in the right coronary artery and his angina symptoms disappeared. However, ventricular tachycardia (VT)/ventricular fibrillation (VF) occurred spontaneously and converted to sinus rhythm with direct current shock (300 J). Oral amiodarone (200 mg/day) and continuous intravenous infusion of nifekalant and lidocaine were started. In addition, a dual chamber implantable cardioverter defibrillator (ICD) for his VT/VF was implanted. However, VT/VF occurred repeatedly after discontinuation of nifekalant. After the administration of bepridil (200 mg/day), VT/VF was completely prevented without nifekalant administration. The hybrid therapy with ICD and oral bepridil is very useful for the treatment of amiodarone resistant ventricular tachyarrhythmia.

Heart rate variability before the onset of ventricular tachycardia: differences between slow and fast arrhythmias

BACKGROUND

We tested whether or not heart rate variability (HRV) changes can serve as early signs of ventricular tachycardia (VT) and predict slow and fast VT in patients with an implantable cardioverter defibrillator (ICD).

METHODS AND RESULTS

We studied the ICD stored 1000 beat-to-beat intervals before the onset of VT (131 episodes) and during a control time without VT (74 series) in 63 chronic heart failure ICD patients. Standard HRV parameters as well as two nonlinear parameters, namely 'Polvar10' from symbolic dynamics and the finite time growth rates 'Fitgra9' were calculated. Comparing the control and the VT series, no linear HRV parameter showed a significant difference. The nonlinear parameters detected a significant increase in short phases with low variability before the onset of VT (for time series with less than 10% ectopy, P<0.05). Subdividing VT into fast (cycle length <or=270 ms) and slow (>270 ms) events, we found that the onset of slow VT was characterized by a significant increase in heart rate, whereas fast VT was triggered during decreased heart rates, compared to the control series.

CONCLUSIONS

Our data may permit the development of automatic ICD algorithms based on nonlinear dynamic HRV parameters to predict VT before it starts. Furthermore, they may facilitate improved prevention strategies.

Body surface area of ST elevation and the presence of late potentials correlate to the inducibility of ventricular tachyarrhythmias in Brugada syndrome

INTRODUCTION

The value of noninvasive markers reflecting repolarization and/or conduction abnormalities in identifying patients with abnormal ECG showing a pattern of atypical right bundle branch block and ST elevation syndrome (Brugada syndrome) at risk for life-threatening arrhythmias is controversial. Because right precordial ST elevation reflects inhomogeneous repolarization, we hypothesized that a correlation between the area of ST elevation, that is, the area of inhomogeneous repolarization, and the inducibility of ventricular tachyarrhythmias (VT) exists. Therefore, the body surface area of ST elevation and the presence of late potentials were compared to the inducibility of VT in patients with the characteristic ECG of Brugada syndrome.

METHODS AND RESULTS

A 120-channel body surface potential map was recorded at rest and after administration of a Class I agent (ajmaline, 1 mg/kg) to measure the body surface area of ST elevation (> or = 0.2 mV) in 23 individuals (16 patients had been resuscitated from near sudden cardiac death or had suffered syncope) with an ECG compatible with the diagnosis of Brugada syndrome as well as in 15 healthy controls and in 15 patients with arrhythmogenic right ventricular cardiomyopathy. Late potentials were assessed in 20 of the Brugada patients using signal-averaged ECG. Programmed ventricular stimulation was performed at two ventricular sites with up to three extrastimuli. Mean body surface area of ST elevation (> or = 0.2 mV) of all Brugada syndrome patients was 154 +/- 139 cm2 (control 9 +/- 9 cm2; P < 0.001). In the group of patients with arrhythmogenic right ventricular cardiomyopathy, only one patient was found to have an area of ST elevation (165 cm2). In the presence of ajmaline, area size increased to 330 +/- 223 cm2 in Brugada syndrome patients (P < 0.05). In patients with inducible sustained (n = 15) and nonsustained VT (n = 3), a mean area of 183 +/- 139 cm2 was found, whereas the area was only 52 +/- 58 cm2 in those with no VT induction (P < 0.05). For an area > or = 50 cm2, there were positive and negative predictive values of 92% and 60%, respectively. Positive late potentials were found in 60% of patients and correlated to the inducibility during programmed ventricular stimulation (positive predictive value 100%, negative predictive value 75%; P < 0.001).

CONCLUSION

In patients with Brugada syndrome, the body surface area of ST elevation and the presence of late potentials correlate to the inducibility of VT during programmed ventricular stimulation and may be of value as a new noninvasive marker for risk stratification in these patients.

Prognostic significance of nonsustained ventricular tachycardia identified postoperatively after coronary artery bypass surgery in patients with left ventricular dysfunction

INTRODUCTION

Nonsustained ventricular tachycardia (NSVT) occurs frequently in the postoperative period (< or = 30 days) after coronary artery bypass graft (CABG) surgery, a setting where many factors may play a role in its genesis. The prognosis of NSVT in this setting in patients with left ventricular (LV) dysfunction is unknown. This study was designed to assess its significance.

METHODS AND RESULTS

We compared the outcome of untreated patients enrolled in the Multicenter Unsustained Tachycardia Trial with coronary artery disease (CAD), LV dysfunction, and NSVT identified postoperatively after CABG (n = 228; mean age 67 years, 84% males) versus nonpostoperative settings (n = 1,302; mean age 66 years, 85% males). Sustained monomorphic ventricular tachycardia was induced in 27% and 33% (P = 0.046) of patients with postoperative and nonpostoperative NSVT, respectively. The 2- and 5-year rates of arrhythmic events were 6% and 16%, respectively, in postoperative patients versus 15% and 29% in nonpostoperative patients (unadjusted P = 0.0020, adjusted P = 0.0082). The 2- and 5-year overall mortality rates were 15% and 36%, respectively, for postoperative patients versus 24% and 47% for nonpostoperative patients (unadjusted P = 0.0005, adjusted P = 0.027). Patients whose NSVT was identified early (<10 days) versus late (10-30 days) after CABG had significantly lower 2- (13% vs 23%) and 5-year (30% vs 52%) mortality rates (unadjusted P = 0.024, adjusted P = 0.018).

CONCLUSION

In this population of patients with CAD and LV dysfunction, the occurrence of postoperative NSVT, especially within 10 days after CABG, portends a far better outcome than when it occurs in nonpostoperative settings. This suggests that in a such setting, NSVT represents a less specific risk factor for future events and should be considered when assigning risk and treatment of similar patients.

Oozing-type of left ventricular rupture treated under percutaneous cardiopulmonary support without surgical repair

A 65-year-old man was admitted to the National Defense Medical College Hospital for acute anterolateral myocardial infarction and cardiogenic shock. Emergency coronary angiography demonstrated occlusion of the proximal left anterior descending artery. Primary percutaneous transluminal coronary angioplasty (PTCA) was successfully performed with the support of intra-aortic balloon pumping (IABP) and medical treatment to stabilize the patient's blood pressure. On the second hospital day, the patient suffered cardiac tamponade. Pericardiocentesis showed bloody fluid and revealed that an oozing-type of left ventricular rupture had occurred after the myocardial infarction. Cardiogenic shock persisted after successful removal of the pericardial effusion. Although the heparinization required during percutaneous cardiopulmonary support (PCPS) can increase pericardial effusion, PCPS was initiated to correct the systemic hypoperfusion; a surgical team was on standby in case massive pericardial effusion resulted, but fortunately that did not occur, and cardiac function recovered. The patient was weaned successfully from PCPS and IABP and has remained in a satisfactory condition for over 1 year. PCPS contributed to the patient's recovery from cardiac shock and may have decreased the effusion from the oozing-type rupture by reducing ventricular wall tension.

Measurement of body surface energy leakage of defibrillation shock by an implantable cardioverter defibrillator

Leakage of electrical current from the body surface during a defibrillation shock delivery by an ICD device was evaluated in 27 patients with life-threatening ventricular tachyarrhythmias. All patients underwent the implantation of the Medtronic Jewel Plus ICD system, and the defibrillation shocks were delivered between the active can implanted in the left subclavicular region and the endocardial lead placed in the right ventricle. At the time of measurement of the effect of electrical energy delivery for defibrillation, the shocks were delivered in a biphasic form at the energy level of 20 or 30 J. During each delivery of the defibrillation shock, the electrical current to the body surface was measured through large skin electrodes (6.2 cm2) that were pasted at the following positions: (1) parallel position: the electrodes were placed at the left shoulder and the right low-chest, and the direction of the electrode vector was parallel to the direction of the defibrillation energy flow, and (2) cross position: the electrodes were placed at the right shoulder and the left low-chest, and the vector of the electrodes was roughly perpendicular to the direction of the energy flow. The energy leakages were measured in 80 defibrillation shocks. The peak leakage current during the shock delivery at energy of 30 J was 48 +/- 26 mA at the parallel position and 19 +/- 15 mA at the cross position (P = 0.0002). The energy leakage at a 30-J shock was 7.4 +/- 7.2 mJ at the parallel position and 1.4 +/- 2.3 mJ at the cross position (P = 0.0002). The actual maximum energy leakage was 105 mA, 29 mJ, and 106 V that appeared at the parallel position. The body surface leakage of the defibrillation energy of the ICD device was evaluated. The power of the energy leakage strongly depended on the angle between the alignment of the recording electrodes and the direction of the energy flow. The highest current leakage to the body surface reached a considerable level, but the energy leakage was small because of the short duration of the defibrillation shock.

Sleep-related breathing disorders are associated with ventricular arrhythmias in patients with an implantable cardioverter-defibrillator

STUDY OBJECTIVES

The aim of this study was to examine the influence of sleep-related breathing disorders (SBDs) on the occurrence of ventricular arrhythmias in patients with reduced left ventricular ejection fraction (LVEF), and life-threatening ventricular tachyarrhythmias treated with an implantable cardioverter-defibrillator.

PATIENTS

Thirty-eight patients with LVEF of 36 +/- 13% (mean +/- SD) underwent a sleep study. When an apnea-hypopnea index (AHI) > 10/h occurred, SBD was diagnosed.

MEASUREMENTS AND RESULTS

In patients with SBDs, ventricular arrhythmias (couplets, triplets, short runs) were recorded simultaneously by Holter ECG and differentiated in episodes with and without disordered breathing. An apnea-associated arrhythmia index (AI) was defined as the number of ventricular arrhythmias occurring simultaneous to disordered breathing. Accordingly, a nonapnea-associated arrhythmia index (NAI) was calculated as the number of ventricular arrhythmias during normal breathing. SBDs were diagnosed in 14 patients: Cheyne-Stokes respiration (CSR) [n = 8; AHI, 32.1 +/- 25.0/h], and obstructive sleep apnea (OSA) [n = 6; AHI, 34.1 +/- 14.6/h]. Four patients in the OSA group and four patients in the CSR group had ventricular arrhythmias during sleep, revealed by Holter ECG. In these eight patients, the AI was significantly higher than the NAI (20.9 +/- 18.8/h vs 4.9 +/- 3.3/h, respectively).

CONCLUSIONS

These data show that ventricular arrhythmias occurred significantly more often in association with disordered breathing in patients at high risk for arrhythmias and reduced LVEF.

Entrainment of ventricular tachycardia with a permanent biventricular pacemaker

Biventricular pacing has been introduced as a treatment for congestive heart failure. These devices presently pace and sense from two disparate ventricular sites. Antitachycardia pacing (ATP) is used for termination of sustained monomorphic ventricular tachycardia (VT) and has been incorporated with simultaneous dual site ventricular pacing for treatment of VT. We report a case of entrainment of sustained monomorphic VT in a 62-year-old female with an ischemic cardiomyopathy and VT, who received a biventricular pacemaker-implantable cardioverter defibrillator, Contak CD (Guidant, St. Paul, MN). Biventricular pacing sites were at the right ventricular apex and the middle of the anterior cardiac vein on the left ventricle. The entrained VT has a left bundle branch block and left axis deviation morphology with a cycle length of 350 msec. ATP at 270 msec produced concealed entrainment of an induced VT. Only one pacing site demonstrated capture. The inability to capture both pacing sites simultaneously was the result of ventricular refractoriness at one of the sites during ATP of the VT. The entrance and exit points of the loop for VT appeared to rest between the two pacing sites in the intraventricular septum. This case illustrates one of the sensing limitations of today's biventricular pacing defibrillator systems.

The implantable cardioverter-defibrillator. Current indications and controversies

The implantable cardioverter-defibrillator (ICD) has become a highly effective, but expensive therapy for sudden cardiac death due to ventricular tachyarrhythmias. ICD use has been increasing at 20-30% per year, and is expected to rise at a faster rate. Clinical trials have now shown that the ICD can be effective for the secondary prevention, and more recently for the primary prevention, of sudden cardiac death in selected populations. Despite the high quality trial evidence that is currently available, several issues pertaining to ICD use remain unresolved. These relate to the management of patient groups who were not included in the clinical trials, optimizing the selection of patients who will benefit from an ICD, determining the duration of survival benefit from an ICD, assessing and optimizing a patient's quality of life with an ICD, and determining the cost-effectiveness and cost-impact of the ICD. These considerations are discussed in this article.

Pathophysiological basis and clinical application of T-wave alternans

We review the contemporary understanding of the pathophysiology of repolarization alternans and present a perspective on the use of T-wave alternans (TWA) as a risk stratification marker of malignant ventricular arrhythmias. Several studies have demonstrated a high correlation of susceptibility to ventricular arrhythmias and sudden cardiac death with the existence of TWA. We describe a number of cellular and molecular alterations in the diseased heart that may provide a link between electrical and mechanical alternans and arrhythmia susceptibility. Repolarization alternans is likely the result of distinct and diverse cellular and molecular alterations that are associated with exaggerated regional repolarization heterogeneity, which renders the heart susceptible to malignant arrhythmias.

Clinical and molecular characterization of patients with catecholaminergic polymorphic ventricular tachycardia

BACKGROUND

Mutations in the cardiac ryanodine receptor gene (RyR2) underlie catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited arrhythmogenic disease occurring in the structurally intact heart. The proportion of patients with CPVT carrying RyR2 mutations is unknown, and the clinical features of RyR2-CPVT as compared with nongenotyped CPVT are undefined.

METHODS AND RESULTS

Patients with documented polymorphic ventricular arrhythmias occurring during physical or emotional stress with a normal heart entered the study. The clinical phenotype of the 30 probands and of 118 family members was evaluated, and mutation screening on the RyR2 gene was performed. Arrhythmias documented in probands were: 14 of 30 bidirectional ventricular tachycardia, 12 of 30 polymorphic ventricular tachycardia, and 4 of 30 catecholaminergic idiopathic ventricular fibrillation; RyR2 mutations were identified in 14 of 30 probands (36% bidirectional ventricular tachycardia, 58% polymorphic ventricular tachycardia, 50% catecholaminergic idiopathic ventricular fibrillation) and in 9 family members (4 silent gene carriers). Genotype-phenotype analysis showed that patients with RyR2 CPVT have events at a younger age than do patients with nongenotyped CPVT and that male sex is a risk factor for syncope in RyR2-CPVT (relative risk=4.2).

CONCLUSIONS

CPVT is a clinically and genetically heterogeneous disease manifesting beyond pediatric age with a spectrum of polymorphic arrhythmias. beta-Blockers reduce arrhythmias, but in 30% of patients an implantable defibrillator may be required. Genetic analysis identifies two groups of patients: Patients with nongenotyped CPVT are predominantly women and become symptomatic later in life; patients with RyR2 CPVT become symptomatic earlier, and men are at higher risk of cardiac events. These data provide a rationale for prompt evaluation and treatment of young men with RyR2 mutations.

[Implantable cardioverter-defibrillator(ICD)]

Implantable Cardioverter-defibrillator(ICD) has been accepted as an effective therapy for the patients with life-threatening ventricular tachyarrhythmias in our country. Especially, down sizing and further development(e.g. atrial sensing/pacing) of ICD generator allows us to consider the indication of the device in the majority of VT/VF patients. Furthermore, not only secondary prevention trials but also primary prevention trials, comparing ICD with the antiarrhythmic agents(mainly amiodarone), demonstrate a superior efficacy of ICD to improve the patients mortality. Under these circumstances, we have to recognize the strong current toward the ICD at the present time. However, an essential problem of ICD therapy, not to prevent VT/VF recurrence, remains to be resolved.

[Heart failure]

Survival of patients with heart failure has improved over the past decade due to advances in medical therapy. However, sudden cardiac death continues to cause 35 to 65% of death. Ventricular arrhythmias are important causes of sudden cardiac death in patients with heart failure. The risks of antiarrhythmic drugs are increased in patients with heart failure. Therefore, in the absence of a clear indication, antiarrhythmic drug therapy should be avoided. A number of recent randomized trials have provided evidence that beta-adrenergic blockers, angiotensin-converting enzyme(ACE) inhibitors and angiotensin II receptor blockers(ARB) significantly reduces the risk of sudden death in patients with chronic congestive heart failure. For patients who have a history of sustained ventricular tachycardia(VT) or ventricular fibrillation(VF) amiodarone or an implantable cardioverter defibrillator(ICD) should be considered, and these therapy may benefit some high risk patients who have nonsustained VT.

Significance and control of cardiac arrhythmias in patients with congestive cardiac failure

A wide spectrum of ventricular and supraventricular tachyarrhythmias occurs in the setting of congestive cardiac failure. However, the two most clinically significant are atrial fibrillation and ventricular tachycardia and fibrillation. In the past there has been much emphasis on premature ventricular contractions and more recently, on nonsustained ventricular tachycardia. For the most part, these arrhythmias are asymptomatic in heart failure. They are markers of sudden arrhythmic death but their suppression by antiarrhythmic drugs have not resulted in a reduction of total mortality. Two approaches have been used to this end. The first is the use of beta-adrenergic blocking drugs and antiarrhythmic agents such as amiodarone. Beta-blockers have been shown to significantly reduce sudden death as well as total mortality, while the effects of amiodarone have been less decisive. The prospective role of the implantable cardioverter defibrillator (ICD) is undergoing critical evaluation in patients with cardiac failure at high risk for sudden death. The elective role of the ICD is well established as first-line therapy in patients with heart failure resuscitated from sudden death and in those with sustained ventricular tachycardia in conjunction with conventional therapies for cardiac decompensation. The prevalence of atrial fibrillation rises as a function of severity of cardiac failure, but it is also in known that persistent atrial fibrillation with an uncontrolled ventricular response may induce heart failure. Controlled ventricular response may prevent congestive heart failure and improve left ventricular function. The two most common causes of atrial fibrillation in cardiac failure in Europe and America are ischemic heart disease and hypertension, while mitral valve disease remains the prevalent cause elsewhere. The choice of antiarrhythmic drugs for maintaining sinus rhythm is critical in the prevention of heart failure aggravation and proarrhythmic reactions of antiarrhythmic drugs. Amiodarone and dofetilide are most widely used in this context.

Devices for the management of ventricular arrhythmias in cardiac failure

Heart failure is a common clinical syndrome with a high morbidity and mortality. Despite advances in medical treatment, death from dangerous ventricular arrhythmias is frequently implicated. Emerging evidence supports the use of the implantable cardioverter defibrillator for selected patients. This includes secondary prevention indications for patients who have survived life-threatening ventricular arrhythmias. In addition, patients who have not suffered spontaneous sustained ventricular arrhythmias, but who are at high risk for sudden arrhythmic death are starting to be recognized as candidates for ICD therapy. At present the only primary prevention indication with a good evidence base is the presence of inducible ventricular arrhythmias at electrophysiologic testing in patients with prior myocardial infarction, impaired left ventricular systolic function and non-sustained ventricular tachycardia on Holter monitoring. Studies planned or in progress are likely to expand further the role of device therapy in the treatment of patients with cardiac failure.

Ventricular mapping during atrial and ventricular pacing. Relationship of multipotential electrograms to ventricular tachycardia reentry circuits after myocardial infarction

AIMS

Conduction through separated myocyte bundles causes multipotential electrograms and reentrant ventricular tachycardia. We hypothesized that without initiating tachycardia, the reentry region could be detected by analysing the change in multipotential electrograms during two different activation sequences.

METHODS AND RESULTS

During catheter mapping and ablation in 16 patients with ventricular tachycardia late after infarction ventricular electrograms were recorded from 1072 sites during atrial and right ventricular paced ventricular activation. Multipotential electrograms were present during both activation sequences at 285 (27%) sites, during atrial pacing only at 159 (15%) sites and during right ventricular pacing only at 152 (14%) sites. Sites with multipotential electrograms during both activation sequences were more often related to a ventricular tachycardia circuit isthmus (43%) as compared to sites where such electrograms were present during one activation sequence (20%). Multipotential electrograms with >2 low amplitude deflections and a >100 ms difference in duration between the two activation sequences were infrequent but highly predictive of the reentry circuit.

CONCLUSION

Regions with fixed multipotentials consistent with conduction block might be useful guides for ablation approaches that target large regions of the infarct, but are not sufficiently specific to be the sole guide for focal ablation approaches.

[Management of lethal ventricular arrhythmias after cardiac surgery]

Arrhythmias are commonly occur after cardiac surgery. Recurrent sustained ventricular tachycardia and ventricular fibrillation in the acute phase after cardiac surgery is the most lethal arrhythmia and may warrant acute intervention and aggressive treatment. Although class I agents are usually ineffective and exacerbate the heart failure in cases with a low ejection fraction, nifekalant(a newer class III agent) and amiodarone can be effective. Hemodynamically tolerable sustained monomorphic ventricular tachycardia can be successfully terminated with ramp or burst pacing via an epicardial ventricular pacing lead. Initiation of intra-aortic balloon pumping and emergency percutaneous cardiopulmonary bypass and emergency catheter ablation can be considered for those patients not responding to the conventional resuscitative measures.

[Review of arrythmias related to acute myocardial infarction and its treatment]

Because reperfusion therapy for AMI has been widely performed, complicated fatal ventricular arrythmias related to AMI has been dramatically decreased. However, there still remain the incidence of fetal arrhythmias such as ventricular fibrillation(VF), ventricular tachycardia(VT) at the early phase in occurrence of AMI. Besides spreading bolus intravenous administration of mutant-tPA, Bystander CPR, Public access defibrillation (PAD), and setting of automated external defibrillators(AED) in the public facilities are actually required to reduce the mortality of AMI. In this article, we reviewed that arrhythmias associated with AMI and strategy for treatments of complicated arrhythmias in the clinical settings.

Implantable cardioverter defibrillator therapy for life-threatening arrhythmias in young patients

OBJECTIVES

This study examined the indications, efficacy and outcomes of implantable cardioverter defibrillator (ICD) use in the pediatric population.

BACKGROUND

ICDs are first-line therapy for adults resuscitated from sudden cardiac death (SCD) or at high risk for life-threatening ventricular arrhythmias. Use of ICDs in children and young adults is infrequent and there are few data regarding this group.

METHODS

We abstracted and analyzed data for all patients in whom ICDs were implanted.

RESULTS

A total of 38 devices were implanted in 27 patients. Age ranged from 6 to 26 years (mean, 14) and weight ranged from 16 to 124 kg (mean, 47). Diagnoses included long QT syndrome (9), hypertrophic cardiomyopathy [6], repaired congenital heart disease [5];, and idiopathic ventricular tachycardia/fibrillation [4]. Indications comprised resuscitated SCD [15], syncope [9], and life-threatening ventricular arrhythmia [3]. Initial device placement was infraclavicular in 13, abdominal in 13 and intrathoracic in 1. Epicardial leads were used with 5 systems. A single coil lead was used in 17. Seven patients, all previously resuscitated from SCD, experienced 88 appropriate successful discharges. There were 6 inappropriate discharges in 3 patients. Mean time to device replacement was 3.1 years (n = 11). Complications included 2 infected systems, 2 lead dislodgments, 2 lead fractures, 1 post-pericardiotomy syndrome, 1 adverse event with defibrillation threshold (DFT); testing, and 1 patient with psychiatric sequelae. No deaths occurred with implanted ICDs.

CONCLUSIONS

These data demonstrate that ICDs provide safe and effective therapy in young patients. The indications for ICDs as primary preventive therapy remain uncertain.

Incidence and management of arrhythmias in women

There are gender-specific differences in the nature and frequency of specific cardiac arrhythmias. Sex-specific variations in the electrophysiologic structure of the heart and/or hormonal effects on modulating ionic channel function may help to explain some of these differences, such as the increased prevalence of symptoms of congenital long QT syndrome in women, and the increase in episodes of supraventricular tachycardia in the perimenstrual period in susceptible patients. On the other hand, women suffer only 20% of sudden cardiac deaths. Fewer women than men have been enrolled in clinical trials for the treatment of ventricular arrhythmias because of difficulty in recruiting female patients, exclusion of women due to comorbid conditions, and/or the later appearance of coronary artery disease in females compared to males. Management of arrhythmias in women is often different from that in men, as women are less likely to receive a dual-chamber pacemaker and to have automatic defibrillator implantation, even when clinically appropriate. These differences may be due to the smaller size of women, a difference in the frequency of comorbid conditions, and patient preference, with women more likely to decline aggressive therapy. This article discusses the differences in presentation and the frequency of specific arrhythmias in women, and suggests measures to improve arrhythmia management in the female patient.

Management of common arrhythmias: Part II. Ventricular arrhythmias and arrhythmias in special populations

In patients without established cardiac disease, the occurrence of premature ventricular complexes without sustained ventricular tachycardia is more an annoyance than a medical risk, and treatment is not required. In contrast, patients with established heart disease and premature ventricular complexes have a higher likelihood of developing ventricular tachycardia or fibrillation. These patients should be treated with a beta blocker or class I antiarrhythmic drug. Treatment of arrhythmias in pregnant women is rarely needed. When treatment is required, amiodarone should be avoided, and beta blockers should be used with caution, because these agents have been associated with fetal growth retardation. The most important rhythm abnormality in athletes is ventricular tachycardia associated with hypertrophic cardiomyopathy. If the presence of the disease is confirmed by echocardiography, beta-blocker therapy is necessary, and these patients should be limited to participation in nonstrenuous sports. Acute arrhythmias in children with Wolff-Parkinson-White syndrome can be treated with adenosine. Radiofrequency ablation of the accessory pathway can provide long-term control.

Electrophysiologically guided amiodarone therapy versus the implantable cardioverter-defibrillator for sustained ventricular tachyarrhythmias after myocardial infarction: results of long-term follow-up

OBJECTIVES

We sought to compare the long-term survival rates of patients with sustained ventricular tachyarrhythmia after myocardial infarction (MI) who were treated according to the results of electrophysiological (EP) study either with amiodarone or an implantable cardioverter-defibrillator (ICD).

BACKGROUND

Patients with sustained ventricular tachyarrhythmias after MI are at high risk of sudden cardiac death (SCD). However, data comparing the long-term survival rates of patients treated with amiodarone or ICD, according to the results of EP testing, are lacking.

METHODS

Patients underwent a first EP study at baseline and a second one after a loading dose of amiodarone of 14 +/- 2.9 g. According to the results of the second EP study, patients were classified either as responders or non-responders to amiodarone; non-responders were eventually treated with an ICD.

RESULTS

Eighty-four consecutive patients with MI (78 men; 21-77 years old; mean left ventricular (LV) ejection fraction 36 +/- 11%) were consecutively included. Forty-three patients (51%) were responders, and 41 patients (49%) were non-responders to amiodarone therapy. During a mean follow-up period of 63 +/- 30 months, SCD and total mortality rates were significantly higher in the amiodarone-treated patients (p = 0.03 and 0.02, respectively).

CONCLUSIONS

The long-term survival of patients with sustained ventricular tachyarrhythmias after MI, with depressed LV function, is significantly better with an ICD than with amiodarone therapy, even when stratified according to the results of the EP study. These patients should benefit from early ICD placement, and any previous amiodarone treatment seems to have no additional value.

Implantable defibrillator use for de novo ventricular tachyarrhythmias encountered after cardiac surgery

De novo postoperative life-threatening ventricular arrhythmias are poorly understood. Long-term benefits of, and need for, treatment is uncertain. To assess the therapeutic advantage of ICD to manage new-onset, life-threatening ventricular tachyarrhythmias after cardiac surgery. Patients included were those with an ICD implanted for de novo life-threatening ventricular tachyarrhythmias encountered 48 hours or more after cardiac surgery. Primary endpoints were total survival, time to first ICD therapy, and appropriateness of ICD therapy. Mean projected survival and projected time to first ICD therapy were calculated by the Kaplan-Meier method. Twenty-seven postoperative patients (left ventricular ejection fraction 0.22 +/- 0.07) were followed for 26 +/- 17.6 months. The index arrhythmia was sustained monomorphic ventricular tachycardia in 17 (63%) and ventricular fibrillation in 10 (37%). Electrophysiological study was positive in 22 (81%) of 27. Total survival and mean projected survival after ICD implant were 22 (81%) of 27 and 25.6 months, respectively, to end of follow-up. The majority received ICD therapy (21/27 [78%]), 20 (74%) of 27 receiving appropriate therapy. The mean time to first ICD therapy and mean projected time to first ICD therapy was 5.6 +/- 7.8 months and 10.5 months, respectively. De novo postoperative ventricular arrhythmias are associated with a high probability of late recurrence. The ICD is useful for these patients.