Sudden Death in Idiopathic Dilated Cardiomyopathy: Role of Ventricular Arrhythmias

Sudden cardiac death (SCD) is associated with idiopathic congestive cardiomyopathy (IDCM) and most commonly is due to ventricular tachyarrhythmias. The recurrence rate of SCD in the absence of specific therapy is thought to be around 20%–30% per year. Asymptomatic and symptomatic ventricular arrhythmias are common in patients with IDCM and the direct causal link of such arrhythmias with SCD in IDCM patients remains to be established. Furthermore, therapy directed at suppressing these ventricular arrhythmias has not been shown to decrease the incidence of SCD. Various approaches such as ambulatory monitoring, eiectrophysiological testing, signal-averaged electrocardiogram, and hemody-namics have met with variable success in identifying patients prone to SCD. Additionally, therapeutic approaches to prevent SCD in IDCM patients have produced equivocal results. This article reviews the published studies addressing the causal link of ventricular arrhythmias to sudden death in patients with IDCM and the attempts to decrease the incidence of sudden.     

Induced Sustained Ventricular Tachycardia in Nonischemic Dilated Cardiomyopathy: Dependence on Clinical Presentation and Response to Antiarrhythmic Agents

Thirty-one patients with nonischemic dilated cardiomyopathy either idiopathic or due to regurgitant valvular disease were studied in the cardiac electrophysiology lab. The indications for study were sustained ventricular tachycardia (VT) in 26, ventricular fibrillation (VF) in 11, and syncope of unknown etiology in 4. Sustained VT was reproducibly induced in 17 patients, including 12 with a history of sustained VT, 2 with VF and 3 with syncope. Of 15 patients undergoing serial antiarrhythmic drug studies, sustained VT was rendered noninducible or nonsustained in 23. Three had recurrent arrhythmic events while on therapy predicted to be effective. One of 2 patients discharged on a regimen predicted to be ineffective had a recurrence of sustained VT that resulted in cardiac arrest. Of 14 patients in whom sustained VT could not he reproducibly induced, 2 subsequently had spontaneous occurrences of sustained VT, and 2 experienced aborted sudden death. These results suggest the following; (1) the induction of sustained VT in the setting of nonischemic dilated cardiomyopathy is dependent on the clinical presentation; (2) antiarrhythmic drugs frequently render sustained VT noninducible or nonsustained; (3) antiarrhythmic drug suppression of inducible sustained VT predicts long-term prevention of spontaneous recurrences; and (4) noninducibility of sustained VT in the baseline state does not predict freedom from subsequent episodes of VT or sudden death.     

扩张型心肌病左室扩张类型与室性心律失常的关系

以24小时动态心电图和二维超声心动图对41例扩张型心肌病患者进行观察,多元回归分析显示:左室舒张末内径与后壁厚度之比(D/T)和室性心律失常程度显著相关。按D/T将患者分为过度扩张型、混合型和肥厚扩张型3组,过度扩张型室性心动过速发生率(91.76%)显著高于混合型(37.5%)和肥厚扩张型(16.7%)。过度扩张型住院病死率50%,显著高于混合型(18.75%);肥厚扩张型无住院死亡。因此,D/T对判断扩张型心肌病易发室性心律失常者具有重要意义。     

Value of Heart Rate Variability to Predict Ventricular Arrhythmias in Recipients of Prophylactic Defibrillators with Idiopathic Dilated Cardiomyopathy

GRIMM, W., et al. : Value of Heart Rate Variability to Predict Ventricular Arrhythmias in Recipients of Prophylactic Defibrillators with Idiopathic Dilated Cardiomyopathy. This study investigated the relation between heart rate variability (HRV) measured as standard deviation of normal to normal RR intervals (SDNN) on baseline 24-hour ambulatory electrocardiogram (ECG) and subsequent appropriate implantable cardioverter defibrillator (ICD) interventions in 70 patients with idiopathic dilated cardiomyopathy (IDC) in whom ICDs were implanted prophylactically in the presence of a low left ventricular ejection fraction (LVEF). During   43 ± 26   months of follow-up, 26 of 70 (37%) study patients with IDC received one or more appropriate ICD interventions for sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) documented by electrograms stored in the ICD. Mean SDNN at ICD implant was   94 ± 33 ms   . No difference was found between patients with   (90 ± 25 ms)   versus without   (96 ± 37 ms)   appropriate ICD interventions for VT or VF during follow-up. Multivariate Cox regression analysis of baseline clinical characteristics including age, gender, LVEF, NYHA functional class, nonsustained VT on Holter, history of syncope, left bundle branch block, baseline medication and HRV revealed LVEF as the only significant predictor of arrhythmia. These findings do not support the use of HRV measured as SDNN on 24-hour ambulatory ECG to select patients with IDC for prophylactic ICD therapy. (PACE 2003; 26[Pt. II]:411–415)     

Magnesium Therapy in Ventricular Arrhythmias

Magnesium (Mg) is the known activator of 300 enzymes which govern energy utilization, cell permeability, and ionic membrane currents in the cardiac conducting cells. This may explain the antiarrhythmic efficacy of Mg in specific clinical settings, despite its only modest electrophysiological effects. This review summarizes the effect of Mg administration in four clinical conditions: in digitalis toxicity; in drug-induced torsade de pointes; in patients with chronic diuretic therapy; and in acute myocardial infarction. Mg effectively abolished ventricular tachyarrhythmias associated with digitalis intoxication. This effect of Mg is related to the activation of sodium-potassium ATP-ase, which is inhibited by digitalis. Drug-induced torsade de pointes was promptly abolished by Mg sulfate in the clinical setting. Experimental studies showed that Mg suppresses the early afterdepolarizations and the triggered activity responsible for occurrence of the arrhythmia. In diuretic-treated hypertensives, potassium depletion has been associated with increased ventricular ectopy and sudden death. Mg has been found to be an important adjuvant for intracellular repletion of potassium in these patients. Several randomized, double-blind studies in patients with acute infarction showed that Mg administered on admission improved survival or reduced the incidence of complex ventricular arrhythmias. Thus, Mg should be employed as first-line therapy in digitalis intoxication and drug-related torsade de pointes, and should be considered an important adjuvant therapy in hypertensives treated with diuretics and patients with acute myocardial infarction.     

扩张型心肌病心脏结构改变与心律失常关系

目的分析１１２例扩张型心肌病（Ｄｉｌａｔｅｄｃａｒｄｉｏｍｙ ｏｐａｔｈｙ,ＤＣＭ）患者心脏结构改变与心律失常的关系。方法用常规心电图、２４小时动态心电图、超声心动图、胸部Ｘ线拍片及血清学分析等检查房性心律失常及室性心律失常及左心房、左心室结构。并排除高血压性心脏病和其他心脏病、糖尿病、电解质紊乱及急性感染所致心律失常。结果ＤＣＭ患者室性心律失常发生率多于房性心律失常,且较早发现,其中恶性心律失常与左室增大有关,房性心律失常与左房肥大有关,左室壁变薄组左室增大较左室壁正常及肥厚组多见。老年ＤＣＭ患者心律失常发生率明显高于非老年ＤＣＭ患者,且与左室及左房增大有关。结论在ＤＣＭ患者,用上述检查（特别是动态心电图和超声心动图）不仅可获得左心室结构改变的信息,而且有利于ＤＣＭ所致心律失常的诊断及与其他疾病所致心律失常的鉴别     

Late Ventricular Potentials and Spontaneous and Induced Ventricular Arrhythmias in Dilated or Hypertrophic Cardiomyopathies. A Prospective Study About 83 Patients

In a series of 83 patients with dilated (DCM) (n = 56) or hypertrophic cardiomyopathies (HCM) (n = 27), were performed 24-hour-Holter monitorings, exercise stress testings, noninvasive recordings of late ventricular potentials (LVP), and programmed ventricular stimulations (PVS) (sinus rhythm and three cycles of stimulation, two extrastimuli, two right ventricle sites) (n = 53). in order to appreciate the frequency of ventricular premature depolarisations (VPDs), to correlate these results with myocardial vulnerability to TV induction, and to compare electrophysiologic and hemodynamic results. Holter monitoring showed that 80% of group A patients had VPDs (75% Lown's grade 3 or over) and 63% in group B (37%≥ grade 3). LVP were found in 15/56 DCM, and 2/27 HCM; in comparison with a control group of 32 normal subjects, the prevalence of LVP was only significant for DCM group. LVP were more frequent in cases of VPD's ≥ Lown's grade 3 at Holter monitoring in DCM group, (33% versus 7% if VPDs ≤ Lown's grade 3) and HCM group (20% versus 0) but the correlation was not significant. Exercise stress testing, conducted only in group E, revealed about 20% of VPDs. PVS provoked ventricular arrhythmia (>5 QRS) in 13 out of 33 cases in group A and in 2 out of 20 cases in group B. There was no significant correlation between the results of these methods of study and those of hemodynamic or echocardiographic explorations except for cardiac index in group A flower when LVP were present, and VPDs ≥ grade 3 during Holter) and end diastolic diameter (larger when PVS provoked fewer ventricular arrhythmias). In group B, PVS induced monomorphic VT in 2/3 patients with syncopes. Thus: (1) ventricular arrhythmias are frequent in cardiomyopathies but LVP had a significant prevalence only in dilated forms; (2) in DCM monomorphic induced VT reproduce spontaneous crisis, whereas in HCM it is possible to provoke VT in patients with syncopes but without this clinical arrhythmia; (3) in DCM as in HCM, ventricular arrhythmia can be independent from hemodynamic disorders.     

Four Chamber Pacing in Dilated Cardiomyopathy

A 54-year-old man received a four chamber pacing system for severe congestive heart failure (NYHA functional Class IV). His ECG showed a left bundle branch block (200-msec QHS duration) with 200-msec PR interval, normal QRS axis, and 90-msec interatrial interval. An acute hemodynamic study with insertion of four temporary leads was performed prior to the implant, which demonstrated a significant increase in cardiac output and decrease of pulmonary capillary wedge pressure. A permanent pacemaker was implanted based on the encouraging results of the acute study. The right chamber leads were introduced by cephalic and suhcla vian approaches. The left atrium was paced with a coronary sinus lead, Medtronic SP 2188–58 model. An epicardial Medtronic 5071 lead was placed on the LV free wall. The four leads were connected to a standard bipolar DDD pacemaker. Chorus 6234. The two atrial leads were connected via a Y-connector to the atrial channel of the pacemaker with a bipolar pacing configuration. The two ventricular leads were connected in a similar fashion to the ventricular channel of the device. The right chamber leads were connected to the distal poles. The left chamber leads were connected to the proximal poles of the pacemaker. Six weeks later, the patient's clinical status improved markedly with a weight loss of 17 kg and disappearance of peripheral edema. His functional class was reduced to NYHA II. Four chamber pacing is technically feasible. In patients with evidence of interventricular dyssynchrony, this original pacing mode probably provides a mechanical activation sequence closer to the natural one. We doubt that this technique will have an impact on long-term survival, but it could be of major importance to improve the patient's well-being and control heart failure.     

Electrophysiological Evaluation of Sustained Ventricular Tachyarrhythmias in Idiopathic Dilated Cardiomyopathy

Sustained ventricular tachyarrhythmias and sudden death are particularly prevalent in patients with idiopathic dilated cardiomyopathy (IDC). In contrast to patients with ischemic heart disease, the value of electrophysiological stimulation (EPS) in patients with IDC has not yet been established. To clarify the role of EPS in these patients, we studied 19 patients (58 +/- 11 years) with IDC who had symptomatic ventricular tachycardia (VT) or ventricular fibrillation (VF). The mean left ventricular ejection fraction was 26 +/- 9%. Ten patients had survived out-of-hospital cardiac arrest, eight had documented sustained monomorphic VT and one patient had non-sustained VT associated with syncope. Thirteen of the 19 patients (68%) had their clinical ventricular tachyarrhythmias induced at EPS (12 VT, 1 VF). In nine of 13 patients (69%), the arrhythmias were subsequently suppressed during serial electrophysiological drug testing. During 17 +/- 11 months of follow-up, 10/19 (53%) patients experienced recurrence of their arrhythmias and nine out of 19 (47%) patients died; six died suddenly and three secondary to heart failure. There was no difference in arrhythmia recurrence between patients with and without inducible ventricular tachyarrhythmias at initial study. Furthermore, suppression of arrhythmia during serial testing did not predict outcome; recurrences were observed in five out of nine patients whose arrhythmias were suppressed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Long Runs of Non-Sustained Ventricular Tachycardia on 24-Hour Ambulatory Electrocardiogram Predict Major Arrhythmic Events in Patients with Idiopathic Dilated Cardiomyopathy

This study examined the prognostic significance of the rate and length of non-sustained (NS) ventricular tachycardia (VT) on 24-hour ambulatory electrocardiograms (ECG) recorded in 343 patients with idiopathic dilated cardiomyopathy (IDC) in the prospective Marburg Cardiomyopathy study. NSVT was defined as ≥3 consecutive ventricular premature beats at >120 bpm. During 52 ± 21 months of follow-up, major arrhythmic events defined as sustained VT, VF, or sudden cardiac death occurred in 46 of 343 patients (13%). Patients with 3–4 beat runs of NSVT had a similar arrhythmia-free survival as patients without NSVT on baseline 24-hour ambulatory ECG. The incidence of major arrhythmic events during follow-up increased significantly from 2% per year in patients without NSVT, to 5% per year in patients with 5–9 beat runs of NSVT, to 10% per year in patients with ≥10 beat runs of NSVT (P < 0.05). Unlike the length, the rate of NSVT was similar in patients with versus without subsequent major arrhythmic events (163 ± 23 vs 160 ± 24 bpm). Thus, the length but not the rate of NSVT on 24-hour ambulatory ECG was a predictor of major arrhythmic events in patients with IDC. The presence of NSVT with ≥10 beat runs on ambulatory ECG was associated with a particularly high risk of major arrhythmic events.     

Marked Improvement in Left Ventricular Function and Significant Reverse Left Ventricular Remodeling within 3 Months of Cardiac Resynchronization Therapy in Patients with Dilated Cardiomyopathy

We monitored reverse left ventricular (LV) remodeling and LV function during the first 6 months of cardiac resynchronization therapy (CRT) in 34 patients (mean age = 55.3 ± 13.6 years, 28 men) with dilated cardiomyopathy (DCM), left bundle branch block, in stable New York Heart Association class III, and on fixed drug regimen who underwent implantation of CRT systems with or without cardioverter defibrillator back-up. QRS-complex duration was reduced from 169.69 ± 19.6 ms (SD) to 144.1 ± 23.4 ms during CRT. Parasternal M-mode and apical 2D-echocardiography was performed before and 3 and 6 months after device implantation. LV enddiastolic (EDD) and endsystolic (ESD) diameters were measured, and biplane LV enddiastolic (EDV), and endsystolic (ESV) volumes and ejection fractions (EF) were calculated using a modified Simpson formula. Significant decreases in LVEDD (P = 0.0064 at 3 months and P = 0.021 at 6 months), LVESD (P = 0.023 at 3 months, and P = 0.003 at 6 months), and LVESV (P = 0.006 resp. P = 0.007), and increases in LVEF (P = 0.003 at 3 months and P < 0.001 at 6 months) were observed. Mean LVEF increased from 23% at baseline to 39% at 6 months. CRT induced prominent reverse LV remodeling and significantly increased LVEF within a few months in patients with DCM.     

Role of Left Ventricular Scar and Purkinje‐Like Potentials During Mapping and Ablation of Ventricular Fibrillation in Dilated Cardiomyopathy

Background: Purkinje‐like potentials (PLPs) have been described as important contributors to initiation of ventricular fibrillation (VF) in patients with normal hearts, ischemic cardiomyopathy, and early after‐myocardial infarction. Methods: Of the 11 consecutive patients with VF storm, nonischemic cardiomyopathy (68 ± 22 years, left ventricular ejection fraction 28 ± 8%) who were given antiarrhythmic drugs and/or heart failure management, five had recurrent VF and underwent electrophysiology study (EPS) and catheter ablation. Results: At EPS, frequent monomorphic premature ventricular contractions (PVC) and/or ventricular tachycardia did not occur. With isoproterenol, VF was induced in three patients, and sustained monomorphic PVCs were induced in one patient. Three‐dimensional electroanatomical mapping using CARTO (Biosense‐Webster Inc., Diamond Bar, CA) revealed posterior wall scar in four of the five patients. PLP in sinus rhythm were recorded around the scar border in these four patients, and radiofrequency ablation targeting PLP was successfully performed at these sites. The patient without PLP did not undergo ablation. During follow‐up (12 ± 5 months), only the patient without PLP had four VF recurrences requiring implantable cardioverter‐defibrillator (ICD) shocks. Conclusion: In patients with VF and dilated cardiomyopathy, left ventricular posterior wall scar in the vicinity of the mitral annulus seems to be a common finding. Targeting PLP along the scar border zone for ablation seems to efficiently prevent VF recurrence in these patients.     

Arrhythmias in Hypertrophic Cardiomyopathy

Supraventricular and ventncular arrhythmias, particularly nonsustained ventricular tachycardia, and ventricular premature beats are a common finding in patients with hypertrophic cardiomyopathy. Several investigations have demonstrated that nonsustained ventricular tachycardia on Holter monitoring is associated with an increased risk of sudden cardiac death. It has been a long lasting controversial discussion whether suppression of these arrhythmias with drugs, such as amiodarone is capable to reduce the incidence of sudden cardiac death. While recent studies have indicated that nonsustained ventricular tachycardia in asymptomatic patients without additional risk factors, such as a positive family history of sudden cardiac death or syncope should not be treated prophylactically with amiodarone. Symptomatic patients with sustained ventricular tachycardias and/or syncope related to ventricular arrhythmias should undergo ICD implantation. The implantation of an ICD in asymptomatic patients should be limited to those who have several risk factors for sudden cardiac death. It is questionable whether other risk stratifiers, such as programmed electrical stimulation may be helpful to identify asymptomatic patients who are at risk to die suddenly. Moreover, whether the demonstration of electrocardiogram fractionation during electrophysiological study is superior to the induction of sustained ventricular arrhythmias for risk stratification, needs further investigation.     

Sudden Bradyarrhythmic Death in Dilated Cardiomyopathy: A Case Report

An 18-year-old male presented with biventricular failure and atrial fibrillation. Detailed investigations revealed the diagnosis of dilated cardiomyopathy. He was put on medical treatment which resulted in symptomatic improvement. One year later he presented with 2 episodes of syncope, with no change in the routine electrocardiogram. A 24-hour ambulatory monitoring was done. The patient died suddenly while on the monitor. Analysis of the terminal event revealed a sudden complete heart block followed by asystole, an event described very rarely in the published literature.     

Right Ventricular Myocardial Function in Patients with Either Idiopathic or Ischemic Dilated Cardiomyopathy Without Clinical Sign of Right Heart Failure: Effects of Cardiac Resynchronization Therapy

Objective: In dilated cardiomyopathy (DCM), right ventricular (RV) dysfunction has been reported and attributed both to altered loading conditions and to RV involvement in the myopathic process. The aim of the study was to detect RV myocardial function in DCM using two‐dimensional (2D) strain echocardiography and to assess the effects of cardiac resynchronization therapy (CRT) on RV myocardial strain during a 6‐month follow‐up. Methods and Results: A total of 110 patients (mean age: 55.4 ± 11.2 years) with either idiopathic (n = 60) or ischemic (n = 50) DCM, without overt clinical signs of RV failure, underwent standard echo and 2D strain analysis of RV longitudinal strain in RV septal and lateral walls. The two groups were comparable for clinical variables (New York Heart Association class III in 81.8%). Left ventricular volumes, ejection fraction, stroke volume, and mitral valve effective regurgitant orifice were similar between the two groups. No significant differences were evidenced in Doppler mitral and tricuspid inflow measurements. RV diameters were mildly increased in patients with idiopathic DCM, while RV tricuspid annulus systolic excursion and Tei‐index were comparable between the two groups. RV global longitudinal strain and regional peak myocardial strain were significantly impaired in patients with idiopathic DCM compared with those having ischemic DCM (all P < 0.001). Using left ventricular end‐systolic volume as marker for response to CRT, 70 patients (63.3%) were long‐term responders. Ischemic DCM patient responders to CRT showed a significant improvement in RV peak systolic strain. Conversely, in patients with idiopathic DCM and in ischemic patients nonresponders to CRT, no improvement in RV function was evidenced. By multivariable analysis, in the overall population, ischemic etiology of DCM (P < 0.0001), positive response to CRT (P < 0.001), and longitudinal intraventricular dyssynchrony (P <0.01) emerged as the only independent determinants of RV global longitudinal strain after CRT. Conclusions: Two‐dimensional strain represents a promising noninvasive technique to assess RV myocardial function in patients with DCM. RV myocardial deformation at baseline and after CRT are more impaired in idiopathic compared with ischemic DCM patients. Future longitudinal studies are warranted to understand the natural history of RV myocardial function, the extent of reversibility of RV dysfunction with CRT, and the possible prognostic impact of such indexes in patients with congestive heart failure.     

Ventricular Arrhythmias in Apparently Healthy Subjects

While it is assumed that the normal heart does not predispose to serious arrhyilimias, several conditions are now being recognized as being associated with short-lasting ventricular arrhythmias. It also becomes clear that idiopathic VT (or repetitive monomorphic VT) sometimes exists on the background of a compromised heart. Whether this dysfunction is due to the arrhythmia or vice versa is not evident. Finally, VF occurs in patients who, at a first glance, have no apparent heart disease, and it is then called idiopathic VF. These complex electrical abnormalities probably reflect disorders, which often are genetically determined. Recognition of these syndromes, often characterized by abnormal repolarization or a disturbed autonomic function is possible if appropriate techniques are used.     

缺血性心肌病与扩张型心肌病的超声比较研究

应用二维多普勒超声心动图对３２例缺血性心肌病（ＩＣＭ）、４２例扩张型心肌病（ＤＣＭ）及３０例正常人（ＮＣ）从心脏形态学结构、血流动力学及房室功能方面进行分析比较。结果：ＤＣＭ组与ＩＣＭ组各超声指标间均有显著性差异（Ｐ＜０．０５或Ｐ＜０．０１）。其特点：①ＤＣＭ组心脏多个房室腔扩大呈球形，室壁变薄及动度弥漫性减弱。ＩＣＭ组以左房室腔扩大为主，多呈葫芦状，室壁节段性运动减弱。②ＤＣＭ组多瓣膜返流发生率     

多普勒组织成像对扩张型心肌病患者左室收缩功能的研究

目的　探讨多普勒组织成像 (Doppler tissue imaging,DTI)评价扩张型心肌病 (dilatedcardiomyopathy,DCM)患者左室收缩功能的应用价值。方法　脉冲 DTI测定左室长轴切面室间隔 (IVS)左室面、右室面及左室后壁 (L VPW)内膜下心肌、外膜下心肌的收缩期运动峰值速度 (Peak- S)。计算左室面与右室面 ,内膜下心肌与外膜下心肌间的速度差 (△ V=peak S1 - peak S2 ) ;心尖四腔切面测定二尖瓣环外侧收缩期运动峰值速度 (Sa峰值速度 )。结果　 DCM患者室壁收缩期运动峰值速度 (peak- S)、内外膜间峰值速度差 (△ V)及 Sa峰值速度较正常人明显降低 ,(P<0 .0 1) ,二尖瓣侧环 Sa峰值速度与 L VE F高度相关 (r=0 .79,P <0 .0 1)。结论　 DTI可作为评价 DCM患者左室局部及整体收缩功能的新方法。