Significance of ventricular tachycardia in idiopathic dilated cardiomyopathy: observations in 35 patients

Dilated cardiomyopathy in children: determinants of outcome

OBJECTIVE

To determine the outcome of dilated cardiomyopathy presenting in childhood and the features that might be useful for prognostic stratification.

SETTING

Supraregional paediatric cardiology unit.

DESIGN

Retrospective analysis.

BACKGROUND

The natural history of dilated cardiomyopathy in children is not well characterised. Previous studies have shown a variable relation between age at presentation and outcome, and sudden death has been infrequent.

METHODS

Retrospective study of 63 consecutive patients with idiopathic dilated cardiomyopathy presenting between 1979 and 1992. Survival curves were constructed by the Kaplan-Meier method.

RESULTS

Age at diagnosis ranged from 1 day to 15 years (median 12 months) and follow up ranged from 1 day to 13 years (median 19 months). Actuarial survival from presentation was 79% at one year (95% confidence interval (95% CI) 66%-88%) and 61% (44%-74%) at five years. Univariate analysis showed that mural thrombus, left ventricular end diastolic pressure > 20 mm Hg, and age at presentation > 2 years were predictors of adverse outcome, but on multivariate analysis only age at presentation was significant. Left ventricular echocardiographic indices either did not improve or deteriorated in 36 children (17 of whom died, four suddenly, and three were transplanted), partially improved in 16 (three of whom died, all suddenly), and returned to normal in 11 (all of whom have survived).

CONCLUSIONS

Older age at presentation and lack of improvement in systolic function are associated with an adverse outcome, and early transplantation should be considered in these patients. There is a persistent risk of late sudden death in those children in whom echocardiographic dimensions remain abnormal.

The role of implantable cardioverter defibrillators in dilated cardiomyopathy

Depending on the severity of the disease, patients with dilative cardiomyopathy (DCM) have a poor prognosis. No definite data are available to show that complex ventricular ectopy, the presence of ventricular late potentials, or programmed electrical stimulation in patients without symptoms with DCM identify patients at risk of sudden cardiac death. Although poor left ventricular function seems to be the most potent predictor of total cardiac death, the prediction of sudden death in patients without symptoms with DCM is poor. Studies with either class I antiarrhythmic drugs or amiodarone have not yet demonstrated a reduction in total mortality rates or sudden death. The usefulness of an implantable cardioverter defibrillator (ICD) in patients without symptoms with DCM is currently under investigation. The usefulness of serial electropharmacologic testing for patients with documented sustained ventricular tachycardia or ventricular fibrillation and DCM is still controversial. Because most patients with DCM and VT or out-of-hospital cardiac arrest have either no inducible ventricular tachyarrhythmia at baseline or the reproducibility of ventricular tachycardia/ventricular fibrillation induction is poor, implantation of an ICD should be considered in most of these patients. The indication for implantation of an ICD should be made on clinical judgment of the patient's functional status and other prognosis-limiting factors, such as rapid progression of heart failure, end-stage heart failure, and age.

Nonsustained ventricular tachycardia: identification and management of high-risk patients

NSVT is common in normal persons and in patients with a variety of heart diseases. When present in patients with coronary artery disease, particularly after a recent myocardial infarction, it is associated with an increased risk of sudden and nonsudden cardiac death. However, its prognostic significance in patients with nonischemic heart disease, with the possible exception of hypertrophic cardiomyopathy, remains controversial. In patients with coronary artery disease, certain diagnostic tools (e.g., determination of left ventricular function. PVS) help to identify low- and high-risk patients who may or may not benefit from antiarrhythmic treatment. There is no consensus at this point as to the best approach for identifying and treating high-risk patients. Ongoing clinical trials should provide important information on the roles of signal-averaged ECGs and PVS in the management of patients with NSVT and coronary artery disease. In the meantime, treatment should be individualized for each patient. beta-Blockers should probably be the first line of therapy to control symptoms. Asymptomatic potentially high-risk patients (i.e., those with LVEF < 40%) should be referred for enrollment in randomized controlled studies.

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, electrophysiological testing, signal-averaged electrocardiogram, and hemodynamics 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.

Prognostic value of an abnormal signal-averaged electrocardiogram in patients with nonischemic congestive cardiomyopathy

BACKGROUND

An abnormal signal-averaged ECG (SAECG) has predictive value for arrhythmic events in patients with coronary artery disease. The purpose of this study was to investigate whether an abnormal SAECG could provide prognostic information in patients with nonischemic dilated cardiomyopathy.

METHODS AND RESULTS

We prospectively obtained SAECGs in 114 patients with dilated nonischemic cardiomyopathy. Twelve-lead ECGs, left ventricular ejection fractions, hemodynamic measurements, and peak exercise oxygen consumption (VO2) also were measured. An SAECG was defined as abnormal by any one of the three following criteria: filtered QRS duration > 120 msec, root-mean-square voltage in the last 40 msec < 20 microV, or duration < 40 microV > 38 msec at 40 Hz. Sixty-six patients had a normal SAECG, 20 patients had an abnormal SAECG, and 28 patients had bundle branch block (BBB). Mean follow-up was 10 +/- 5 months. Age, ejection fraction, peak VO2, pulmonary capillary wedge pressure, and cardiac index were not statistically different among the three groups. Use of antiarrhythmic drugs was similar among the three groups, although patients with BBB had more implantable defibrillators (p < 0.05). The incidence of previous atrial arrhythmias was similar for the three groups. Patients with abnormal SAECG or BBB had more past episodes of sustained ventricular tachycardia and/or sudden death episodes (n = 9) than patients with normal SAECG (n = 1) (p < 0.01). Prospectively, none of the 66 patients with normal SAECG died suddenly or had sustained ventricular arrhythmias. Two deaths occurred from progressive heart failure, and three patients required urgent transplant. In the 20 patients with an abnormal SAECG, four patients had sustained ventricular tachycardia, five patients died suddenly, two patients died from progressive heart failure, and one patient required urgent transplant. In the patients with BBB, four patients had sustained ventricular tachycardia, and four patients required urgent transplant. One-year event-free survival, i.e., absence of ventricular tachycardia and/or death, was 95% in patients with normal SAECG, 88% in patients with BBB, and only 39% in patients with an abnormal SAECG (p < 0.001). Multivariate analysis demonstrated that SAECG and New York Heart Association classification were independent predictors of survival.

CONCLUSIONS

Patients with an abnormal SAECG had a statistically significant increase in sustained ventricular arrhythmias and/or death than did patients with a normal SAECG or BBB. This study demonstrates that an abnormal SAECG is a marker of past and future arrhythmic events in patients with nonischemic dilated cardiomyopathy. In contrast, patients with a dilated cardiomyopathy with a normal SAECG have an excellent prognosis with adverse outcome only from progressive heart failure.

First- or second-degree atrioventricular block as a risk factor in idiopathic dilated cardiomyopathy

To evaluate the significance of clinical, hemodynamic and electrocardiographic risk factors in idiopathic dilated cardiomyopathy 94 patients were followed prospectively for 49 +/- 37 months. During follow-up, 30 patients died, 13 died suddenly, 13 died of congestive heart failure and 4 of other causes. Follow-up was completed in 85 patients, and overall cardiac mortality was 31%. Univariate analysis revealed left ventricular ejection fraction among 20 variables as the major indicator of risk of both cardiac death of all causes and sudden cardiac death separately. Multivariate overall analysis determined 3 independent risk factors in the following order for all causes of cardiac death: Ventricular pairs > 40/24 hours (RR 7.2, p < 0.0001), left ventricular ejection fraction < or = 35% (RR 6.5, p < 0.001) and first- or second-degree atrioventricular (AV) block (RR 3.1, p < 0.05). In the subset of patients with ejection fraction < or = 35% ventricular pairs > 40 per 24 hours (RR 10.7, p < 0.001), AV block (RR 3.9, p < 0.05), and the missing administration of vasodilators (RR 3.3, p < 0.05) were the most important. The chief risk factors for sudden cardiac death were age (RR 7.4, p < 0.01) and AV block (RR 4.6, p < 0.05) by adjustment for age, and ejection fraction < or = 35% (RR 7.1, p < 0.01) and AV block (RR 4.2, p < 0.05) if not adjusted for age. A differentiation into 4 risk groups was attempted. The additional independent prognostic importance of AV block was shown, especially in combination with reduced ejection fraction or a high incidence of ventricular pairs.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular arrhythmias in heart failure

Heart failure is an increasingly common disorder leading to reduced quality and expectancy of life. Asymptomatic and symptomatic ventricular arrhythmias are a frequent complication and have been found to be independent prognostic predictors for sudden cardiac death in patients with heart failure. Unfortunately, the positive predictive failure for this finding is low, but in patients with sustained ventricular arrhythmias, variables indicating impaired pump function are the most important predictors of sudden and of nonsudden cardiac death. Arrhythmias in heart failure may have many different underlying mechanisms. Indications for, and mode of treatment of, arrhythmias in heart failure depend on the symptoms and prognostic significance of the arrhythmia. Primarily, pump function should be optimized and antiarrhythmic drug therapy instituted only when the arrhythmia persists. In poorly tolerated and life-threatening arrhythmias, implantable devices allowing pacing and defibrillation must be considered. No data are presently available indicating a protective role of antiarrhythmic drugs in the prevention of sudden cardiac death in heart failure. Future directions should concentrate on the development of better stratification of risk for sudden death, better delineation of mechanisms of arrhythmias in heart failure (allowing the development of mechanism-specific antiarrhythmic drugs), and research into new nonpharmacologic techniques such as cardiomyoplasty and molecular biologic techniques to rebuild the failing heart muscles.

Nocturnal hypoxia and arrhythmias in patients with impaired left ventricular function

OBJECTIVES

To document the incidence of hypoxic episodes in a series of patients with impaired left ventricular function, and to correlate the occurrence of hypoxia with severity of arrhythmia.

PATIENTS

34 patients with breathlessness and clinical evidence of left ventricular dysfunction.

MAIN OUTCOME MEASURES

Simultaneous overnight finger oximetry and electrocardiographic monitoring.

RESULTS

High grade arrhythmias (Lown grade > III) occurred in 20/34 (59%) of patients, and frequent dips in oxygen saturation were noticed (mean dip frequency 4.8/h, range 0.1-20.0). 20/34 (59%) of patients had episodic hypoxaemia, including 13/34 (38%) with a classical Cheyne Stokes pattern. There was a correlation between dip frequency and the presence of high grade arrhythmias (those with high grade arrhythmia had mean (SD) 6.7 (5.5) dips/h v 2.2 (3.4) in those without, p < 0.01); there was also a correlation between the presence of arrhythmias and episodic hypoxaemia (episodic hypoxaemia in those with high grade arrhythmias occurred in 17/20 (85%) v 3/14 (21%) of those without arrhythmias, p < 0.002). There was no correlation between the presence of high grade arrhythmias or dip frequency and the extent of left ventricular impairment, which was present in all patients (mean (SD) ejection fraction 26% (13%)).

CONCLUSION

Noticeable abnormalities of nocturnal oxygen saturation occur in patients with impaired left ventricular function, and these are associated with high grade arrhythmias. Interventions that limit desaturation may have valuable anti-arrhythmic effects.

Sudden death in idiopathic dilated cardiomyopathy

Approximately 30% of deaths among patients with IDCM are sudden. Although ventricular tachyarrhythmias are responsible for many of these deaths, bradyarrhythmias may also play a significant role. Patients with a previous history of sustained ventricular arrhythmias are at high risk for sudden death. In patients without prior symptomatic ventricular arrhythmias a history of unexplained syncope, severely impaired right ventricular hemodynamics, frequent spontaneous ventricular ectopy or NSVT, and inducible SMVT may help identify those at greatest risk of dying suddenly. With the exception of angiotensin-converting enzyme inhibitor therapy, attempts at pharmacologic prevention of sudden death have had limited efficacy. The implantable defibrillator offers promising results in survivors of previous sustained ventricular arrhythmias; its prophylactic use in other high-risk subgroups is the subject of active investigation.

Resting and ambulatory ECG predictors of mode of death in dilated cardiomyopathy

With the purpose of verifying whether the electrocardiogram (ECG) pattern alone can predict the mode of death in dilated cardiomyopathy, data from 12-lead ECGs and 48-hour arrhythmia monitoring were evaluated in 67 patients with dilated cardiomyopathy. During a mean follow-up period of 3 +/- 2 years, death from congestive heart failure occurred in 18 patients (27%), whereas 10 (15%) died suddenly (NS). Multivariate analysis showed that left bundle branch block (p < 0.001) and left atrial enlargement (p < 0.001) were independently related to death from congestive heart failure. Ventricular arrhythmias of Lown grade 4A or 4B (p < 0.001) and repolarization time, as assessed by QTc-QRS interval (p < 0.05), were independent predictors of sudden death. It is concluded that ECG features alone may be helpful for risk factor characterization of dilated cardiomyopathy patients, provided that multiple ECG criteria are utilized at time of diagnosis.

Ventricular arrhythmia in congestive heart failure

The importance of ventricular arrhythmia is based on its association with sudden death. In certain groups of patients, ventricular arrhythmia--primarily runs of nonsustained ventricular tachycardia (NSVT)--is associated with an increased risk for sudden death. Although this relationship has been most often reported in patients with recent myocardial infarction, it has also been recognized in patients with dilated cardiomyopathy, regardless of etiology. Therefore, ventricular arrhythmia is common in patients with CHF due to cardiomyopathy. A number of studies have reported that 70-95% of patients with cardiomyopathy and congestive heart failure (CHF) have frequent ventricular premature beats, and 40-80% will manifest runs of NSVT. Many factors are responsible for ventricular arrhythmia in such patients, including structural abnormalities, electrolyte imbalance, hemodynamic impairment, activation of neurohormonal mechanisms, and pharmacologic therapy. Many studies have reported a high yearly mortality in patients with cardiomyopathy and CHF; greater than 40% of deaths are sudden, most often the result of sustained ventricular tachyarrhythmia. Most studies have noted an association between presence (and frequency) of NSVT and risk of sudden cardiac death in these patients. Unfortunately, other techniques--such as the signal-averaged electrocardiogram and electrophysiologic testing--are not helpful in identifying the individual at risk. Although several drug interventions will reduce mortality from progressive CHF, these drugs have not been shown to reduce sudden death and, indeed, have a variable effect on ventricular arrhythmia. Although NSVT is a marker for increased risk for sudden death, it is uncertain if antiarrhythmic drugs will prevent this outcome. Antiarrhythmic drugs have not been shown to be effective for preventing sudden death, although there are as yet no well-controlled randomized trials. Several studies suggest that amiodarone and beta blockers are beneficial, but this requires confirmation. For patients who have been resuscitated following an episode of sudden death due to a sustained ventricular tachyarrhythmia, antiarrhythmic therapy guided by invasive and noninvasive techniques appears to reduce risk of recurrent arrhythmia. However, the response rate to antiarrhythmic agents is low and side effects are common in patients with CHF. Especially important is the increased risk of precipitating CHF and aggravating the arrhythmia being treated. For many such patients who have had serious ventricular tachyarrhythmia, the automatic implantable cardioverter defibrillator may prove a better option. Other drugs used for management of CHF reduce overall mortality, but not risk of sudden death.

Ventricular arrhythmias in dilated cardiomyopathy as an independent prognostic hallmark. Italian Multicenter Cardiomyopathy Study (SPIC) Group

Prevalence and characteristics of ventricular arrhythmias (VA) on Holter monitoring were evaluated in 218 patients with invasively documented idiopathic dilated cardiomyopathy to clarify their relation to pump dysfunction, and their prognostic role. VA were observed in 205 patients (94%) and were high grade (ventricular pairs or tachycardia) in 130 (60%). No simple or multiform ventricular premature complexes were present in 88 patients (group 1; 41%), ventricular pairs in 63 (group 2; 32%), and ventricular tachycardia in 67 (group 3; 27%). Only echocardiographic right ventricular dimensions (p less than 0.05) and prevalence of VA during effort (8% in group 1, 15% in group 2, and 14% in group 3; p = 0.0005) differed significantly between groups. VA severity, and number of ventricular premature beats and tachycardia episodes were not correlated to right/left ventricular dimensions and pump function indexes. During a mean follow-up of 29 +/- 16 months, 27 patients died from cardiac events, and 16 received transplants. Three-year survival probability was lower in groups 2 (0.82) and 3 (0.81) than in group 1 (0.94). By Cox multivariate analysis, VA severity (p less than 0.01) was a major independent predictor of prognosis after markers of ventricular dysfunction such as left ventricular ejection fraction (p less than 0.001) and stroke work index (p less than 0.001).

Survival of heart failure patients with preserved versus impaired systolic function: the prognostic implication of blood pressure

The impact of impaired versus preserved systolic function on survival of patients with heart failure was investigated in 78 patients with decompensated heart failure. Patients were classified on the basis of their left ventricular systolic performance, as defined by fractional shortening (FS); group I (n = 56) had impaired systolic function (FS less than 24%) and group II (n = 22) had preserved systolic function (FS greater than or equal to 24%). Mean ejection fraction was 15 +/- 5% and 40 +/- 13% for these groups, respectively. By the end of 48 months, 36 patients in group I had died compared with only 22 patients in group II (p less than 0.05). Both systolic and diastolic blood pressure were significantly lower in the deceased patients compared with the survivors in group I (p less than 0.05). There was a trend for an opposite direction in the relationship of blood pressure to mortality in group II. We conclude that the prognosis of patients with heart failure and preserved systolic function is more favorable than that of those with impaired function, and that blood pressure may have a differential prognostic meaning in the two groups.

Sudden death in patients with congestive heart failure: future directions

Sudden, unexpected cardiac death continues to be a major clinical problem in patients with congestive heat failure. This review summarizes the current state of knowledge regarding the identification and management of these patients. The roles of ambulatory ECG monitoring, electrophysiological testing, signal-averaged ECG, and other methods of predicting increased risk of sudden death are discussed. The modes of sudden cardiac death and the potential mechanisms of ventricular arrhythmias in congestive heart failure are reviewed. Current therapeutic options including antiarrhythmic drugs, neurohormonal blockade, and automatic implantable cardioverter defibrillators are discussed. Finally, future directions and ongoing clinical investigations of the management of these complex patients are considered.

Clinical course of idiopathic dilated cardiomyopathy in children

Previous studies in adults with dilated cardiomyopathy suggest that the presence of arrhythmia, especially ventricular tachycardia, correlates with increased mortality. We performed a retrospective analysis of 63 children with idiopathic dilated cardiomyopathy to determine the prognostic significance of arrhythmias and other findings with respect to mortality. The mean age at diagnosis of the cardiomyopathy was 4.96 +/- 5.3 years. The overall mortality rate was 16% over a 10 year follow-up period. Persistent congestive heart failure and ST-T wave changes correlated with increased mortality (p less than 0.05). No other variables affected outcome. Arrhythmias were found in 46% of the patients; of the arrhythmias, 48% were atrial arrhythmias. Ventricular tachycardia was present in six patients. Death occurred in 4 (14%) of 29 patients with known arrhythmia; 1 of the 5 died suddenly. The remaining 6 deaths in the series occurred in the 34 patients without a documented arrhythmia. It is concluded that 1) arrhythmias are frequently seen in children with dilated cardiomyopathy but are not predictive of outcome; 2) sudden death in children with this disease is rare; and 3) persistent congestive heart failure portends a poor prognosis.

Diagnostic value of ventricular stimulation in patients with idiopathic dilated cardiomyopathy

To assess the response to programmed ventricular stimulation and the clinical outcome, we performed a prospective study in 103 patients with idiopathic dilated cardiomyopathy. The protocol used up to three extrastimuli delivered at two right ventricular sites during sinus rhythm and ventricular pacing at 100 and 150 beats/min and was repeated during infusion of 1 to 4 micrograms/min of isoproterenol. Sustained monomorphic ventricular tachycardia (VT) was induced in 8 of 11 patients with spontaneous sustained VT, in none of 35 patients without significant ventricular arrhythmias during Holter monitoring, and in 9 of 56 patients with salvos of ventricular premature beats. Isoproterenol infusion facilitated the induction of two episodes of sustained VT in patients with spontaneous sustained VT; however, in all but one of the remaining patients, induction of ventricular tachyarrhythmias was not impaired. During the follow-up period there were eight sudden deaths among patients who initially had syncope, inducible sustained VT, or both and three episodes of sustained VT in patients who initially had nonsustained VT but inducible sustained VT. Isoproterenol infusion can be used to safely facilitate induction of ventricular tachyarrhythmias in patients with dilated cardiomyopathy. The induction of sustained VT was associated with a poor prognosis.

Prognostic value of thallium-201 perfusion defects in idiopathic dilated cardiomyopathy

To assess the prognostic significance of thallium-201 perfusion defects in patients with idiopathic dilated cardiomyopathy (IDC), 43 patients underwent thallium scintigraphy in addition to clinical, echocardiographic, angiographic and hemodynamic evaluation. Eleven patients had no significant thallium perfusion abnormality, 19 had multiple small defects and 13 had a large defect. During 3.2 +/- 2.2 years, 14 patients had disease-related mortality. The patients who died had a higher incidence of ventricular tachycardia (71 vs 31%; p less than 0.02), increased cardiothoracic ratio (60 +/- 6 vs 54 +/- 6; p = 0.005), decreased fractional shortening (11 +/- 6 vs 15 +/- 5; p less than 0.05), increased pulmonary wedge pressure (15 +/- 7 vs 10 +/- 6 mm Hg; p = 0.05), increased left ventricular end-diastolic pressure (21 +/- 8 vs 14 +/- 6 mm Hg; p = 0.02) and abnormal thallium perfusion defects (13 of 14 vs 16 of 26; p less than 0.05) compared with survivors. Age, gender, left ventricular end-systolic and end-diastolic dimensions, cardiac index and ejection fraction were not statistically different in the survivors versus the patients who died. Kaplan-Meier survival estimates at 1, 3 and 5 years were 100% in patients without significant perfusion abnormality; 89, 77 and 64%, respectively, in patients with multiple small defects; and 84, 76 and 30%, respectively, in patients with a large defect (p less than 0.025 by log rank test).(ABSTRACT TRUNCATED AT 250 WORDS)

The value of oral amiodarone in the treatment of ventricular arrhythmias in heart disease

The antiarrhythmic properties of amiodarone at the ventricular level were discovered in the early 1970s. The unanimously recognised efficacy of amiodarone includes a weak negative inotropic effect and compensatory vasodilatory properties, making amiodarone particularly suitable for treating the potentially malignant arrhythmias associated with organic disease. In a review of 611 hospitalised patients on amiodarone, and 353 patients in whom the drug had been prescribed, over a 52-month period in our 60-bed department, we noted that amiodarone was prescribed in 53% of patients for arrhythmias and in 47% of patients for coronary insufficiency. Ventricular arrhythmias represented 13% of the rhythmic indications. These indications differ from those in the USA. The efficacy (70 to 90%) of amiodarone in ventricular extrasystoles has been shown in open studies. In coronary patients, the antiarrhythmic activity of amiodarone is superior to that of propranolol. However, there has been no controlled study because the need for a loading dosage, and the electrocardiographic effects render such studies difficult. After myocardial infarction, ventricular arrhythmias constitute a significant risk factor independently of prognosis; amiodarone may be useful in this indication, and studies of the European Myocardial Infarction Amiodarone Trial (EMIAT) type will examine its value here. Since 1973, it has been recognised that amiodarone can prevent ventricular tachycardia in 55 to 89% of patients in the clinical situation. After a long-standing controversy, the positive predictive value of programmed stimulation has finally been agreed on. In hypertrophic cardiomyopathy, retrospective studies suggest a reduction in mortality in patients treated with amiodarone. By contrast, the value of amiodarone in dilated cardiomyopathy requires more intensive investigation. We consider amiodarone to be indicated in ventricular arrhythmic complexes, particularly if they are associated with an ejection fraction of less than 35% and/or atrial fibrillation. The value of amiodarone in arrhythmias associated with heart failure needs to be evaluated. In conclusion, amiodarone is a powerful antiarrhythmic agent but, because of the possibility of dose- and duration-dependent side effects, evaluation of the risk: benefit ratio in each indication is needed.

Potentially lethal ventricular arrhythmias. Minimizing the danger

Patients with potentially lethal ventricular arrhythmias are at an increased risk of sudden death. Antiarrhythmic drugs, with the exception of beta blockers and possibly amiodarone, have not been particularly effective in reducing mortality. Beta blockers have been used successfully to treat survivors of myocardial infarction, including patients with significant impairment of ventricular function. Evidence to date suggests that use of low-dose amiodarone may be appropriate for selected patients with chronic heart failure and potentially lethal ventricular arrhythmias.

Comparison of frequency of late potentials in idiopathic dilated cardiomyopathy and ischemic cardiomyopathy with advanced congestive heart failure and their usefulness in predicting sudden death

Signal-averaged electrocardiograms were obtained in 62 consecutive patients with advanced congestive heart failure (CHF) undergoing evaluation for possible heart transplantation to determine if late potentials: (1) provide unique information compared to assessment of ventricular ectopic activity on ambulatory electrocardiogram, and (2) identify a subgroup of CHF patients with higher sudden death risk. Patients with a history of cardiac arrest or sustained ventricular tachycardia were excluded. CHF was due to old myocardial infarction in 40 patients and idiopathic dilated cardiomyopathy in 22 patients. Late potentials were present in 16 of 40 (40%) patients with old infarction but in only 3 of 22 (14%) patients with nonischemic CHF (p = 0.03). Twenty-four-hour ambulatory electrocardiograms were obtained in 34 patients (55%). Total ventricular ectopic activity and repetitive forms of ectopy were similar in patients with and without late potentials. Nine patients died suddenly, 9 had nonsudden death, 15 underwent heart transplantation and 29 were alive and well after a mean follow-up of 218 +/- 154 days. At 1 year, the actuarial risk of death was 37% and of sudden death was 20%. Sudden death risk was 12% in patients with late potentials versus 21% in those without (p = 0.73). Thus, the incidence of the arrhythmia substrate producing late potentials depends on the CHF etiology. The signal-averaged electrocardiogram and ambulatory electrocardiogram provide independent information for possible risk assessment in CHF. However, late potentials are poor predictors of sudden death risk when CHF is advanced, possibly due to the heterogeneity of causes of sudden death--ventricular tachycardia being only 1 of many possible mechanisms.

Prognostic role of inducible ventricular tachycardia in patients with dilated cardiomyopathy and asymptomatic nonsustained ventricular tachycardia

We studied the prognostic relevance of inducible ventricular tachycardia in 32 patients with dilated cardiomyopathy and spontaneous nonsustained asymptomatic ventricular tachycardia. Programmed ventricular stimulation included basic drive cycle lengths of 600, 500, 430, 370, 330 and 300 msec at single, double, and triple extrastimuli. Ventricular tachycardia (greater than or equal to 6 beats) was initiated in 7 patients (22%), with sustained monomorphic ventricular tachycardia being seen in 4 of them. During median follow-up of 21 months (13-44), 14 patients died. Sudden cardiac death occurred in two of the seven patients with inducible tachycardia and in only one of the 25 patients in whom it was not possible to induce tachycardia. Although patients with inducible tachycardia did not differ clinically from those in whom tachycardia could not be induced, the projected mean survival time was significantly shorter in those with inducible tachycardia (10 months vs. 32 months, P = 0.04). For late sudden cardiac death, the positive predictive value of inducible tachycardia was 28%. The negative predictive value was 96%. We conclude that induction of ventricular tachycardia by programmed stimulation might indicate poorer prognosis in patients with dilated cardiomyopathy.

Relation of complex ventricular arrhythmias to presenting features and prognosis in dilated cardiomyopathy

To evaluate whether complex ventricular arrhythmias relate to presenting features and prognosis of dilated cardiomyopathy, 104 patients were studied from 1977 to 1987. At diagnosis, the 19 patients with complex ventricular arrhythmias (18%), as compared to the 85 patients without (82%), had a higher incidence of palpitation (P less than 0.01), severe dyspnea (P less than 0.001) and atrial fibrillation (P less than 0.01). They showed also higher mean right atrial pressures (10 +/- 5 vs 6 +/- 4 mm Hg, P less than 0.001) and higher right ventricular end-diastolic pressures (11 +/- 4 vs. 7 +/- 4 mm Hg, P less than 0.001) than patients without complex ventricular arrhythmias. Histologic samples were collected from the 32 patients (31%) studied since 1984 and semiquantitatively graded. The 11 patients with complex ventricular arrhythmias showed a higher frequency of severe interstitial fibrosis than the 21 patients without (64% vs. 24%, P less than 0.05), but they were otherwise similar as to the frequency of marked myocellular hypertrophy, changes of myocardial regression, endocardial fibrosis, attenuation of myocytes, hyperplasia of smooth muscle cells and infiltration by inflammatory cells. During a follow-up of 3.8 +/- 3.5 years, 35 patients (34%) died. Mortality was 58% (11 out of 19) in patients with complex ventricular arrhythmias and 28% (24 out of 85) in patients without (P less than 0.025). These results show that complex ventricular arrhythmias in dilated cardiomyopathy are associated with impairment of function of the right heart and severe interstitial fibrosis of the left ventricle, rather than with left ventricular dysfunction. Presence of complex ventricular arrhythmias also seems to identify those at high risk for death.

Arrhythmias and mortality in congestive heart failure

The extent and severity of myocardial dysfunction and risk of dying are associated with the occurrence of ventricular arrhythmias. However, there is a dissociation between the frequency of ventricular arrhythmias and the prevalence of sudden death among patients with congestive heart failure. Sudden death occurs in 8 to 10% of New York Heart Association functional class I patients and in 20% of class II, III and IV patients, despite increased frequency of malignant arrhythmias and functional deterioration. Yearly mortality rates increase from 12 to 15% in class I and II and is 60% in class IV. Sudden death in class I and II is 50 to 60% of all deaths, whereas in class IV it amounts to only 20 to 30%. The most important cause of death in class IV is progressive congestive heart failure. Ventricular arrhythmia is a trigger event in the development of fatal arrhythmia which depends on a substrate of myocardial scar tissue, hypertrophy and aberrant conducting pathways. However, regional myocardial ischemia, transmembrane electrolyte differences and myocardial stores of catecholamines are important modulators. Depletion of myocardial catecholamines and down-regulation of myocardial beta-adrenergic receptors in the myocardium may explain tolerance to ventricular tachyarrhythmias observed in patients with severe congestive heart failure and intolerance to conventional antiarrhythmic drugs. Although angiotensin-converting enzyme (ACE) inhibitors may reduce ventricular arrhythmias, the important role of ACE inhibitors in severe congestive heart failure is to prevent progression of myocardial dysfunction and congestive heart failure. To date, however, ACE inhibitors have not been demonstrated to have a significant effect on the incidence of sudden death. This does not preclude an effect on fatal arrhythmias among patients with milder heart failure and intact stores of myocardial catecholamines.

Prediction of outcome in late-stage cardiomyopathy

One hundred thirty-three patients with dilated heart failure, 80 with coronary artery disease, and 53 with idiopathic dilated cardiomyopathy were followed for a mean of 29 months. Patients with ischemic heart disease had a worse prognosis than those classified as having idiopathic cardiomyopathy. Features from history, physical examination, and diagnostic tests done when patients were referred to our clinic were checked for univariate association with survival and were used in Cox model survival analysis to define risk groups. Neither the overall group nor either subgroup showed a relationship between ejection fraction and survival. The best variables for predicting long-term mortality included underlying coronary artery disease, basal systolic blood pressure of less than 120 mm Hg, presence of congestion on chest radiogram, and age over 64. Other variables did not improve risk prediction in the overall group. Among patients with ischemic heart disease, blood pressure, congestion, maximal heart rate on treadmill test, and the presence of left bundle branch block on the initial electrocardiogram all contributed. Only systolic blood pressure and the symptom score were related to survival in idiopathic cardiomyopathy.

Effect of acute hemodynamic decompensation on electrical inducibility of ventricular arrhythmias in patients with dilated cardiomyopathy and complex nonsustained ventricular arrhythmias

In patients with dilated cardiomyopathy, hemodynamic decompensation has been postulated to increase vulnerability to reentrant ventricular arrhythmias. To test this hypothesis, we performed programmed ventricular stimulation with three extrastimuli on nine patients with dilated cardiomyopathy and asymptomatic complex ventricular arrhythmias during a period of acute hemodynamic decompensation; programmed ventricular stimulation was then repeated following hemodynamic improvement with nitroprusside. These patients did not have a history of documented or suspected sustained ventricular tachycardia or fibrillation. The mean left ventricular ejection fraction was 0.21 +/- 0.04 (range 0.15 to 0.26). In the baseline state, mean right atrial pressure was 8 +/- 4 mm Hg, pulmonary artery wedge pressure was 20 +/- 3 mm Hg, and cardiac index was 3.2 +/- 0.5 L/min/m2. Following acute hemodynamic decompensation, mean right atrial pressure increased to 16 +/- 5 mm Hg and pulmonary artery wedge pressure to 33 +/- 8 mm Hg; cardiac index decreased to 2.1 +/- 0.5 L/min/m2. In this decompensated state, programmed ventricular stimulation failed to induce sustained or nonsustained ventricular arrhythmias in any patient. Following nitroprusside administration (mean dose 1.5 +/- 1.1 micrograms/kg/min), there were significant decreases in mean right atrial pressure (11 +/- 3 mm Hg) and pulmonary artery wedge pressure (16 +/- 3 mm Hg), and a significant increase in cardiac index (3.1 +/- 1.1 L/min/m2) (p less than 0.05 for all values versus the decompensated state). In the improved hemodynamic state, programmed ventricular stimulation induced nonsustained ventricular tachycardia (six beats) in only one patient, and sustained arrhythmias in none.(ABSTRACT TRUNCATED AT 250 WORDS)

Stretch-induced arrhythmias in the isolated canine ventricle. Evidence for the importance of mechanoelectrical feedback

Alterations in loading conditions and muscle length influence the electrophysiology of ventricular myocardium and may play a role in arrhythmogenesis in globally dilated or dyskinetic ventricles. To test the hypothesis that stretch can initiate arrhythmias in normal myocardium, the response to graded mechanical stretch was studied in seven isolated blood-perfused canine ventricles. After eight conditioning contractions produced by His bundle pacing (2 Hz), global stretch of the ventricle was produced by a servocontrolled pump that abruptly increased ventricular volume by a precise amount (delta V) during early diastole and then returned ventricular volume to the initial holding volume (Vi). Ventricular premature contractions were readily produced; ventricular couplets and short runs of ventricular tachycardia were occasionally elicited. The probability of a stretch-induced arrhythmia was determined from multiple alternating sequences in which a stretch of known amplitude (delta V) or no stretch was delivered. As delta V was increased, the probability of a stretch-induced arrhythmia was low initially, increased sharply after a threshold was exceeded, and approaching 100% with physiological volumes. With Vi set to a standard value of 20 ml, corresponding to end-diastolic pressure of 5.3 +/- 5.2 mm Hg (mean +/- SD), the delta V resulting in a 50% chance of a stretch-induced arrhythmia (delta V50) was 15.0 +/- 1.6 ml. A decline in delta V50 was consistently observed when Vi was increased. While delta V50 values were remarkably similar (10.7% coefficient of variation), the pressure at the time the ventricular premature depolarization was triggered was highly variable for different ventricles; this finding suggests that myocardial strain is more important than absolute level of wall stress in the initiation of these arrhythmias. These results demonstrate that myocardial stretch predictably initiates arrhythmias and that the susceptibility to stretch-induced arrhythmias is enhanced by ventricular dilatation. Thus, ventricular ectopy in patients with regionally or globally dilated hearts may arise, in part, by a mechanism of myocardial stretch.

Antiarrhythmic drug therapy for congestive heart failure with focus on moricizine

Many patients who have serious ventricular arrhythmia requiring antiarrhythmic drug therapy have congestive heart failure (CHF). However, the pharmacokinetic and pharmacodynamic properties of the antiarrhythmic drugs are altered in the presence of CHF. It has been reported that some adverse effects, primarily aggravation of arrhythmia and CHF occur more frequently in patients with a history of left ventricular (LV) dysfunction. Moreover, antiarrhythmic drugs are less effective in patients with a history of CHF and a reduced LV ejection fraction (LVEF). Moricizine, a new antiarrhythmic drug, has been undergoing clinical trials for over 13 years in the United States. The data base involving 1,072 patients was analyzed to establish the effect of this agent in patients with CHF. The presence of CHF does not alter the absorption, half-life and clearance of moricizine. The incidence of CHF exacerbation definitely related to moricizine was low (2%) and occurred primarily in patients with a history of CHF. Aggravation of arrhythmia and conduction abnormalities also occurred more often in patients with prior CHF. However, the incidence of all other adverse effects involving other organ systems was the same in patients with and without CHF and was also unrelated to the baseline LVEF. The effect of moricizine for suppressing spontaneously occurring ventricular ectopy was also similar in patients with and without CHF and was independent of LVEF. However, the drug is less effective in preventing sustained ventricular arrhythmia in patients with CHF.

Angiographic and electrophysiologic substrates of ventricular tachycardia in chronic Chagasic myocarditis

Forty-three consecutive symptomatic patients with chronic Chagasic myocarditis and ventricular tachycardia (VT) underwent clinical evaluation, 24-hour Holter monitoring, left ventricular angiography and electrophysiologic testing including programmed ventricular stimulation at 3 drive cycle lengths at 2 sites in the right ventricle. The mean ejection fraction was 42 +/- 10%. Sixteen patients had clinical sustained VT and 27 nonsustained VT. VT was reproducibly initiated in 13 of 16 (81%) patients with sustained VT and in 14 of 27 (52%) patients with nonsustained VT. Electrocardiographic conduction disturbances were seen in 15 of 16 (94%) patients with sustained VT and in 17 of 27 (63%) patients with nonsustained VT (p less than 0.05). Five of 16 (31%) sustained VT and none of nonsustained VT patients had left ventricular aneurysms (p less than 0.05). These data indicate that VT is frequently inducible in patients with sustained VT and nonsustained VT and chronic Chagasic myocarditis. An association appears to be present between conduction disturbances on the electrocardiogram, left ventricular aneurysms and development of sustained ventricular arrhythmias.

Ventricular ectopic activity: prevalence and risk

Ambulatory electrocardiographic monitoring and the frequent use of stress electrocardiography have been important tools in characterizing the prevalence and prognostic importance of ventricular ectopic activity in both healthy persons and patients with organic heart disease. These studies have demonstrated that ventricular ectopy is not uncommon in persons with no evidence of heart disease. However, it is rarely of high density or repetitive, and even when frequent or repetitive, or both, carries little, if any, risk of sudden death in patients without syncope. However, in patients with organic heart disease and in certain clinical settings, frequent and repetitive ventricular ectopy identifies a population at high risk for arrhythmia-induced syncope or sudden death. These rhythm disturbances have particular prognostic importance in ischemic heart disease with depressed left ventricular function and hypertrophic cardiomyopathy. Patients with presyncope or syncope and structural heart disease who demonstrate frequent and repetitive ventricular ectopy are also a high-risk group. Therefore, individual risk stratification is important in deciding whether and how to treat patients with ventricular ectopy.

Predictors of total mortality and sudden death in mild to moderate heart failure. Captopril-Digoxin Study Group

The relation between baseline clinical variables and subsequent mortality was examined in 295 patients with mild to moderate heart failure who participated in a multicenter trial comparing the effect on treadmill exercise tolerance of captopril, digoxin and placebo given in addition to a diuretic drug. At baseline study, all patients had a left ventricular ejection fraction less than or equal to 40%; 81% were in New York Heart Association functional class II. The etiology of heart failure was ischemic in 62% and nonischemic in 38%. During an average follow-up period of 16 months, 47 patients (16%) died and 24 deaths were classified as sudden. By univariate analysis, left ventricular ejection fraction, ventricular premature beat frequency, couplet frequency, ventricular tachycardia frequency, functional class, treadmill exercise time and nonischemic heart disease were statistically associated with mortality. With multiple logistic regression analysis, left ventricular ejection fraction was identified as the variable most closely associated with total mortality (p = 0.006). Twenty-seven percent of patients with an ejection fraction less than or equal to 20% died compared with 7% with an ejection fraction greater than or equal to 30%. Ventricular tachycardia frequency on Holter monitoring was independently associated with both total mortality (p = 0.008) and sudden death (p = 0.003). Patients with a ventricular tachycardia frequency of greater than 0.088 events/h had a mortality rate of 34% compared with 12% in those without ventricular tachycardia. In the multivariate model, functional class (p = 0.02) and etiology of nonischemic heart disease (p = 0.04) remained as independent predictors of mortality, whereas treadmill exercise duration did not.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular arrhythmias in congestive heart failure

Despite advances in the treatment of congestive heart failure (CHF), the mortality rate continues to be high. A large number of the deaths are sudden, presumably due to ventricular arrhythmias. Complex ventricular arrhythmias are recorded in as many as 80% of patients with CHF, with nonsustained ventricular tachycardia occurring in 40%. The latter appears to be an independent predictor of mortality. Chronic structural abnormalities responsible for CHF may be the basis for the capability of a ventricle to support life-threatening arrhythmias, which are triggered by premature ventricular contractions. The pathogenesis of arrhythmias is multifactorial. Electrolyte abnormalities, ischemia, catecholamines, inotropic and antiarrhythmic drugs may worsen arrhythmias and increase susceptibility of a ventricle to sustained arrhythmias. Beta-adrenergic blockers and angiotensin-converting enzyme inhibitors have a beneficial effect. The role of various drugs in the pathogenesis and treatment of ventricular arrhythmias is discussed. The efficacy of antiarrhythmic therapy targeted to asymptomatic nonsustained ventricular tachycardia, in order to prevent sudden death, is controversial. Pharmacotherapy guided by electrophysiologic testing is the treatment of choice for patients who have manifest sustained ventricular tachycardia, but patients resuscitated from ventricular fibrillation may require automatic implantable cardioverter defibrillator.

Potentially lethal ventricular arrhythmias: from mundane to esoteric

Patients with potentially lethal ventricular arrhythmias (VAs) represent a heterogenous group with frequent and high grade ventricular arrhythmias (including couplets and runs of nonsustained ventricular tachycardia), structural heart disease and decreased left ventricular function. This is a group at intermediate risk of sudden death, with risks varying from 10% to 38%. The electrical and mechanical risks of patients with potentially lethal VA is discussed in relation to their ability of promoting sudden death. The studies reviewing the impact of antiarrhythmic treatment on survival of patients with potentially lethal VA is discussed.