Dilated cardiomyopathy: functional status, hemodynamics, arrhythmias, and prognosis

Arrhythmic risk stratification in non-ischaemic dilated cardiomyopathy beyond ejection fraction

Sudden cardiac death and arrhythmia-related events in patients with non-ischaemic dilated cardiomyopathy (NICM) have been significantly reduced over the last couple of decades as a result of evidence-based pharmacological and non-pharmacological therapeutic strategies. Nevertheless, the arrhythmic stratification in patients with NICM remains extremely challenging, and the simple indication based on left ventricular ejection fraction appears to be insufficient. Therefore, clinicians need to go beyond the current criteria for implantable cardioverter-defibrillator implantation in the direction of a multiparametric evaluation of arrhythmic risk. Several parameters for arrhythmic risk stratification, ranging from electrocardiographic, echocardiographic, imaging-derived and genetic markers, are crucial for proper arrhythmic risk stratification and a multiparametric evaluation of risk in patients with NICM. In particular, integration of cardiac magnetic resonance parameters (mostly late gadolinium enhancement) and specific genetic information (ie, presence of LMNA, PLN, FLNC mutations) appears fundamental for proper implementation of the current arrhythmic risk stratification. Finally, a novel approach focused on both arrhythmic risk and prediction of left ventricular reverse remodelling during follow-up might be useful for effective multiparametric and dynamic arrhythmic risk stratification in NICM. In the future, a complete and integrated evaluation might be mandatory to implement arrhythmic risk prediction in patients with NICM and to discriminate the competing risk between heart failure-related events and life-threatening arrhythmias.

Are nonsustained ventricular tachycardias predictive of major arrhythmias in patients with dilated cardiomyopathy on optimal medical treatment?

BACKGROUND

To evaluate the role of nonsustained ventricular tachycardias (NSVT) for the prediction of major ventricular arrhythmias (MVA) in patients with idiopathic dilated cardiomyopathy (DCM) after optimization of medical treatment.

METHODS AND RESULTS

Three hundred nineteen consecutive DCM patients were evaluated after adequate stabilization on optimal angiotensin-converting enzyme (ACE) inhibitor (88%) and beta-blocker (82%) therapy. Frequency, length, and rate of NSVT at 24-hour Holter monitoring were analyzed to assess their values in predicting MVA (unexpected sudden death, SVT, ventricular fibrillation, and appropriate implantable cardioverter defibrillator interventions). During follow-up (median 96 months, 1(st)-3(rd) interquartile range 52-130), MVA incidence was low, and not statistically different between patients with and without NSVT (3 and 2 per 100 patient-years, respectively, P = nonsignificant [NS] at log-rank analysis). At multivariable analysis, the number of NSVT was predictive of MVA only if left ventricular ejection fraction (LVEF) was > 0.35 (two NSVT/day vs no NSVT/day: hazard ratio [HR] 5.3, 95% confidence interval [CI] 1.59-17.85 in LVEF > 0.35 vs HR 0.93, 95% CI 0.3-2.81 in LVEF < or = 0.35). Consequently, in patients with LVEF < or = 0.35, MVA incidence rates were similar regardless of NSVT (3.6 and 4.1 patient-years, respectively, in those with and without NSVT, P = NS), while in patients with LVEF > 0.35, MVA incidence (3.1 per 100 patient-years vs 0.9 per 100 patient-years, P = 0.003) was significantly higher when NSVT were present.

CONCLUSIONS

After medical stabilization, NSVT did not increase the risk of MVA in patients with DCM and LVEF < or = 0.35. Conversely, the number and length of NSVT runs were significantly related to the occurrence of MVA in the patients with LVEF > 0.35.

Gene expression analysis of ischemic and nonischemic cardiomyopathy: shared and distinct genes in the development of heart failure

Cardiomyopathy can be initiated by many factors, but the pathways from unique inciting mechanisms to the common end point of ventricular dilation and reduced cardiac output are unclear. We previously described a microarray-based prediction algorithm differentiating nonischemic (NICM) from ischemic cardiomyopathy (ICM) using nearest shrunken centroids. Accordingly, we tested the hypothesis that NICM and ICM would have both shared and distinct differentially expressed genes relative to normal hearts and compared gene expression of 21 NICM and 10 ICM samples with that of 6 nonfailing (NF) hearts using Affymetrix U133A GeneChips and significance analysis of microarrays. Compared with NF, 257 genes were differentially expressed in NICM and 72 genes in ICM. Only 41 genes were shared between the two comparisons, mainly involved in cell growth and signal transduction. Those uniquely expressed in NICM were frequently involved in metabolism, and those in ICM more often had catalytic activity. Novel genes included angiotensin-converting enzyme-2 (ACE2), which was upregulated in NICM but not ICM, suggesting that ACE2 may offer differential therapeutic efficacy in NICM and ICM. In addition, a tumor necrosis factor receptor was downregulated in both NICM and ICM, demonstrating the different signaling pathways involved in heart failure pathophysiology. These results offer novel insight into unique disease-specific gene expression that exists between end-stage cardiomyopathy of different etiologies. This analysis demonstrates that transcriptome analysis offers insight into pathogenesis-based therapies in heart failure management and complements studies using expression-based profiling to diagnose heart failure of different etiologies.

Prognostic value of ambulatory electrocardiography monitoring in patients with dilated cardiomyopathy

BACKGROUND

Performance of ambulatory electrocardiography (AECG) may provide data useful for counseling patients regarding prognosis and for selecting potential patients for defibrillator implantation, but this practice remains controversial.

METHODS

We reviewed clinical and AECG data on 355 patients diagnosed with dilated cardiomyopathy (DCM). Predictors of survival were identified in a multivariable analysis using a Cox proportional hazard model. Ability of the derived model to predict outcomes was tested using a second cohort of 144 patients.

RESULTS

Nonsustained ventricular tachycardia (NSVT) was present on AECG in 31% of the subjects. Ambulatory electrocardiography provided 3 independent predictors of mortality: NSVT (relative risk [RR], 1.63; 95% confidence interval [CI], 1.06-2.51; P = .02), mean heart rate (RR, 1.03; 95% CI, 1.02-1.04; P = .0001), and heart rate range (RR, 0.990; 95% CI, 0.982-0.997; P = .008). Performance of the multivariable model was validated (area under the curve = 0.83) on a second cohort of patients.

CONCLUSION

Ambulatory electrocardiography provides useful prognostic information in patients with DCM, identifying 3 independent predictors of mortality.

[Perioperative implications of heart transplant]

Over the past 30 years, heart transplantation has evolved into a definitive therapy for patients with end-stage cardiomyopathy. However, perioperative management of patients undergoing heart transplantation remains a challenge for anesthesiologists. The presence of biventricular failure, arrhythmias and associated multisystem organ dysfunction may contribute to significant intraoperative hemodynamic instability prior to the initiation of cardiopulmonary bypass (CPB). Even after an uneventful transplantation, weaning from CPB may be difficult. Acute right ventricular failure can develop in the recipient secondary to pre-existing pulmonary hypertension. Treatment options frequently focus on therapeutic interventions directed towards decreasing pulmonary vascular resistance and improving right ventricular contractility. Intraoperative use of transesophageal echocardiography (TEE) enables the anesthesiologist to diagnose acute right ventricular failure early on and guide therapy. Concurrent pathology including kinking of the pulmonary artery anastomosis or valvular insufficiency in the transplanted heart can also be recognized and addressed. The number of patients undergoing cardiac transplantation is continually increasing. In addition, the use of more effective immunosuppressive agents has curtailed transplant rejection and permitted longer survival. Consequently, heart transplant recipients are more frequently presenting for non-cardiac surgical procedures. Thus, an understanding of physiological and pharmacological implications associated with heart transplantation is crucial for managing these patients in the perioperative period.

Deceleration time of early filling in patients with left ventricular systolic dysfunction: functional and prognostic independent value

BACKGROUND

Although diastolic function parameters have been mentioned as significant predictors of functional capacity and prognosis in patients with left ventricular (LV) systolic dysfunction, it has not been fully elucidated whether they keep an independent predictive value when multiple parameters from a wide variety of examinations are considered.

METHODS

We prospectively studied 60 patients with New York Heart Association (NYHA) class II-IV chronic heart failure symptoms and LV ejection fraction <0.4. At the time of entry into the study, demographic data and functional class were obtained, and usual Doppler echocardiographic, radionuclide ventriculographic, cardiopulmonary exercise testing and hemodynamic variables were determined. Deceleration time of early filling (DT) and NYHA functional class were the only independent predictors of functional capacity as assessed by means of peak oxygen uptake (peak VO2). Mean follow-up was 21 +/- 6 months, and event-free survival was defined as the absence of cardiac death, urgent cardiac transplantation, or hospital admission requiring inotropic or mechanical support.

RESULTS

Multivariate Cox analysis showed that DT (P =.008), peak VO2 (P =.01), and NYHA class (P =.02) were independent predictors of event-free survival at 1 year. Patients in the lowest tertile of DT (<130 ms) had a significantly lower event-free survival than patients in the intermediate (44% vs 80%, P =.03) and in the highest tertile (44% vs 83%, P =.02). Patients with both a DT <130 milliseconds and a peak VO2 <14 mL/kg/min had the highest rate of events at 1 year (83% vs 22% for the remaining patients, relative risk 3.75, P <.001).

CONCLUSIONS

In patients with LV systolic dysfunction, DT is a powerful independent predictor of functional capacity and prognosis among a wide variety of variables. A shortened DT (<130 ms) identifies a subgroup of patients with a worse outcome, especially when combined with a reduced peak VO2 (<14 mL/kg/min).

Results of ambulatory electrocardiography in overtly healthy Doberman Pinschers with echocardiographic abnormalities

OBJECTIVE

To identify, by means of 24-hour ambulatory electrocardiography, electrocardiographic abnormalities in overtly healthy Doberman Pinschers in which results of echocardiography were abnormal.

DESIGN

Clinical case series.

ANIMALS

56 (35 male, 21 female) overtly healthy Doberman Pinschers with echocardiographic evidence of cardiomyopathy on initial examination that subsequently died of cardiomyopathy.

PROCEDURE

Twenty-four-hour ambulatory electrocardiographic (Holter) recordings obtained at the time of initial examination were reviewed. For all dogs, scan quality was > 90%.

RESULTS

Initial Holter recordings of all 56 dogs contained ventricular premature contractions (VPC). Thirty-six (65%) dogs had > 1,000 VPC/24 h, 17 (31%) had > 5,000 VPC/24 h, and 11 (19%) had > 10,000 VPC/24 h. Fifty-four (96%) dogs had couplets of VPC, 37 (66%) had triplets of VPC, and 36 (64%) had episodes of nonsustained (< 30 seconds) ventricular tachycardia. Number of VPC/24 h during the initial Holter recordings was positively correlated with numbers of couplets and triplets of VPC and number of ventricular escape beats and negatively correlated with left ventricular fractional shortening. Twenty-eight dogs died suddenly prior to the putative onset of congestive heart failure.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that along with echocardiography, 24-hour ambulatory electrocardiography can be used to help identify overtly healthy Doberman Pinschers with cardiomyopathy.

Arrhythmias in heart failure: current concepts of mechanisms and therapy

About one half of deaths in patients with heart failure are sudden, mostly due to ventricular tachycardia (VT) degenerating to ventricular fibrillation or immediate ventricular fibrillation. In severe heart failure, sudden cardiac death also may occur due to bradyarrhythmias. Other dysrhythmias complicating heart failure include atrial and ventricular extrasystoles, atrial fibrillation (AF), and sustained and nonsustained ventricular tachyarrhythmias. The exact mechanism of the increased vulnerability to arrhythmias is not known. Depending on the etiology of heart failure, different preconditions, including ischemia or structural alterations such as fibrosis or myocardial scarring, may be prominent. Reentrant mechanisms around scar tissue, afterdepolarizations, and triggered activity due to changes in calcium metabolism significantly contribute to arrhythmogenesis. Furthermore, alterations in potassium currents leading to action potential prolongation and an increase in dispersion of repolarization play a significant role. Treatment of arrhythmias is necessary either because patients are symptomatic or to reduce the risk for sudden cardiac death. The individual history, left ventricular function, electrophysiologic testing, and the signal-averaged ECG give useful information for identifying patients at risk for sudden cardiac death. The implantable cardioverter defibrillator (ICD) has evolved as a promising therapy for life-threatening arrhythmias. A potential role may exist for antiarrhythmic drugs, mainly amiodarone. There is growing evidence that patients with sustained VT or a history of resuscitation have the best outcome with ICD therapy regardless of the degree of heart failure. Many of these patients require additional antiarrhythmic therapy because of AF or nonsustained VTs that may activate the device. Catheter ablation or map-guided endocardial resection are additional options in selected patients but seldom represent the only therapeutic strategy.

Myocardial contractile reserve on dobutamine echocardiography predicts late spontaneous improvement in cardiac function in patients with recent onset idiopathic dilated cardiomyopathy

OBJECTIVES

The purpose of this study was to determine whether identification of contractile reserve with dobutamine would predict recovery of myocardial function during follow-up in patients with recent onset idiopathic dilated cardiomyopathy (IDC).

BACKGROUND

The prognosis of patients presenting with new onset IDC is variable and difficult to predict.

METHODS

Twenty-two patients (17 men, 5 women, 46 +/- 14 years) with recently diagnosed IDC (4 +/- 3 months) underwent dobutamine echocardiography. Left ventricular ejection fraction (LVEF) and LV sphericity before and at peak dobutamine infusion (30 +/- 11 microg/kg/min) were determined. A follow-up echocardiographic assessment was done at 6 +/- 4 months.

RESULTS

The LVEF on dobutamine was directly related to baseline LV mass expressed as g/ml (Pearson r = 0.65, p = 0.0003). Baseline variables that were significantly predictive of follow-up LVEF were deceleration time (r = 0.69, p = 0.0006), wall motion score index (WMSI) (r = -0.63, p = 0.002), LV mass (r = 0.56, p = 0.008) and LVEF on dobutamine (r = 0.84, p = 0.0001). When either deceleration time or WMSI or LV mass was entered into a regression equation to predict follow-up LVEF, the LVEF on dobutamine added significantly to predictive power. However, if LVEF on dobutamine was entered first, none of the other three variables added significantly to prediction. Baseline LV sphericity at end diastole (ED) (r = 0.13, p = 0.6) did not correlate with follow-up LV sphericity in ED, whereas LV sphericity in ED on dobutamine (ED [r = 0.70, p = 0.0004]) correlated with LV sphericity in ED on follow up.

CONCLUSIONS

This study demonstrates that dobutamine-induced improvement in baseline LVEF and LV sphericity identifies patients with IDC who exhibit substantial improvement in LV function and geometry over time.

Treatment of end stage dilated cardiomyopathy

Patients should be referred for cardiac transplantation only after all other means of management of congestive heart failure have been attempted and have been unsuccessful (table 3). An adequate therapeutic trial of conventional and experimental agents including beta blockade and vesnarinone should be completed and be shown to be unsuccessful before transplantation is considered in patients in NYHA class III. Prospective clinical trials need to be completed to define the role of newer therapeutic options. The scarcity of donor organs will probably preclude the use of cardiac transplantation in all patients who may benefit. Alternative methods of cardiac replacement (such as dynamic cardiomyoplasty, permanent implantable mechanical circulatory assistance, and xenografting) must be developed. These methods coupled with better pharmacological treatment will greatly improve the outcome of patients with dilated cardiomyopathy.

Dilated cardiomyopathy in children: clinical course and prognosis

The clinical profile of 19 patients with dilated cardiomyopathy ages 2-18 years (mean 13.4 +/- 4 years) was reviewed to detect any factors that might be predictive for their survival. Follow-up range from 5 to 105 months (mean 39 +/- 33 months). Routine treatment consisted of digitalis and diuretics: 14 patients received antiarrhythmics, 6 received vasodilators, and 12 were managed with immunosuppression. There were 12 survivors and 7 nonsurvivors: The 1-year mortality was 21.2% and the 2-year mortality 35.8%. All deaths were within first 2 years. Of the 12 patients who survived 2 years, a significant improvement was noticed in 9. In 3 patients tachycardia-induced cardiomyopathy was diagnosed, and abolition of supraventricular tachycardia was followed by improvement and regression of cardiomegaly. Endomyocardial biopsy was performed in 16 patients. Four with a histologic diagnosis of active myocarditis survived, and in 3 of them a considerable improvement was noticed. Of the 12 patients with nonspecific histologic findings, 6 died (p < 0.05). There were no significant differences between survivors and nonsurvivors for any of the following parameters: incidence of severe heart failure (NYHA class III-IV) and severe ventricular arrhythmias (Lown class III-V), relative heart volume, echocardiographic left ventricular diastolic diameter and shortening fraction, and the hemodynamic parameters of cardiac index, left ventricular ejection fraction, left ventricular end-diastolic pressure, and left ventricular end-diastolic volume index.

Restrictive left ventricular filling pattern in dilated cardiomyopathy assessed by Doppler echocardiography: clinical, echocardiographic and hemodynamic correlations and prognostic implications. Heart Muscle Disease Study Group

OBJECTIVES

This study was undertaken to evaluate the frequency of restrictive left ventricular filling pattern in dilated cardiomyopathy, as well as its clinical and hemodynamic correlations and prognostic implications.

BACKGROUND

In dilated cardiomyopathy, as in other heart diseases, different left ventricular filling patterns were observed on Doppler echocardiography. Some patients showed a "restrictive filling pattern," similar to that associated with restrictive cardiomyopathy, characterized by predominant E waves and a shortened E deceleration time.

METHODS

Pulsed Doppler transmitral curves were analyzed in 79 consecutive patients with dilated cardiomyopathy assigned to two study groups according to E deceleration time: group 1 (n = 36) had a restrictive left ventricular filling pattern (E deceleration time < 115 ms); group 2 (n = 43) had an E deceleration time > or = 115 ms.

RESULTS

Patients in group 1 were significantly younger, in a higher New York Heart Association functional class, more frequently had a third heart sound and had a higher left ventricular filling pressure at catheterization. In addition, they showed more severe left and right ventricular dysfunction and dilation, a larger left atrium and more severe mitral regurgitation. A restrictive filling pattern was associated at Doppler study with a higher E wave velocity, lower A wave velocity and higher E/A ratio. During a follow-up interval of 22 +/- 14 months, all 14 patients who subsequently died or required heart transplantation showed a restrictive left ventricular filling pattern. At multivariate analysis, E deceleration time was the most powerful independent prognostic indicator of poor outcome or transplantation.

CONCLUSIONS

Restrictive left ventricular filling pattern is frequent in dilated cardiomyopathy, is associated with more severe disease and is a powerful indicator of increased mortality risk and need for heart transplantation.

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).

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.

Clinical and pathologic study of familial dilated cardiomyopathy

To evaluate the occurrence of familial cases of dilated cardiomyopathy (DC), 165 consecutive patients were studied. Diagnosis of myocardial disease was based on clinical, hemodynamic, bioptic, postmortem or a combination of these criteria. Twelve patients (7% of cases) showed evidence of myocardial disease in greater than or equal to 1 relative; 27 patients with myocardial disease were detected in the 12 families, but a suspected history of myocardial involvement was present in a further 16 cases. In 6 families proband and relatives were affected by DC (total 14 cases); in 1 of these families the disease began with an atrioventricular block. In 4 families the relatives showed the presence of myocarditis at the endomyocardial biopsy. In 2 families the relatives presented a right ventricular cardiomyopathy. The mode of inheritance was autosomal dominant in 7 families, recessive in 4; X-linked pattern may be hypothesized in 1. Nine patients died under the age of 45 years: 2 of sudden death, 6 of chronic heart failure and 1 of cerebral embolism. Familial transmission is not rare. Different modes of genetic transmission (autosomal dominant, recessive and X-linked) and different forms of myocardial disease suggest that familial DC may be a multifactorial disease.

Mildly dilated congestive cardiomyopathy. Use of prospective diagnostic criteria and description of the clinical course without heart transplantation

Prognosis in classically described dilated congestive cardiomyopathy has been reported to be related to ventricular size. Mildly dilated congestive cardiomyopathy (MDCM) has been defined as end-stage heart failure of unknown etiology (New York Heart Association class IV, left ventricular ejection fraction less than 30%), occurring with neither typical hemodynamic signs of restrictive myopathy nor significant ventricular dilatation (less than 15% above normal range). The present study includes follow-up in 12 nontransplant patients. In the first 4 months after diagnosis, two patients improved and are living, and two showed cardiac dilation and clinical deterioration and died. Six of the remaining eight with persistent MDCM died (four with intractable heart failure and two, sudden deaths) without change in ventricular size before death, despite medical therapy over 20 +/- 8 months. Eight comparable transplanted patients with persistent MDCM demonstrated improved total survival by life table analysis (p less than 0.05). A family history of congestive cardiomyopathy was found in nine of 16 patients (56%) with persistent MDCM. Nontransplant patients were older (p less than 0.02), but other findings were similar in the two groups. Endomyocardial biopsies available in 14 of 16 cases showed little or no myofibrillar loss in spite of severe hemodynamic impairment. The degree of myofibrillar loss did not correlate with hemodynamic parameters but showed good correlation with left ventricular size, that is, five of six patients with no myofibrillar loss had normal ventricular size, whereas all eight patients with mild myofibrillar loss had mild cardiomegaly (p less than 0.002). Our current experience suggests a somewhat variable but negative prognosis after prospective diagnosis of MDCM, with poor survival in patients with persistence of the original diagnostic features during follow-up. Preservation of heart size in MDCM is probably related to lack of significant myofibrillar loss. Thus, irrespective of heart size or myofibrillar preservation on biopsy, heart transplantation should be strongly considered in MDCM if signs of severe cardiac dysfunction persist despite therapy.

Dilated cardiomyopathy and myocarditis: natural history, etiology, clinical manifestations, and management

This monograph begins and ends with a statement of uncertainty regarding many aspects of dilated cardiomyopathy. Natural history studies identify patients with widely differing outcomes. A host of prognostic factors have emerged, yet it would appear that the major determinants of survival are as yet unrecognized. The diagnosis remains primarily one of exclusion, and management is largely nonspecific and supportive. The frequency of sudden cardiac death is well documented, but the ability to accurately identify patients at risk and the efficacy of antiarrhythmic therapy is unestablished. The emerging success of cardiac transplantation is a source of encouragement. The causes of dilated cardiomyopathy remain a source of intense investigation. Accumulating evidence (much of it circumstantial) does, however, implicate a viral etiology and perhaps altered function of the immunoregulatory system. However, the disparity between the severity of functional disturbance with the relative lack of histologic markers of cellular necrosis implies a disturbance at a cellular level. The etiology or etiologies remain elusive. Future investigation directed at fundamental aspects of cardiac cellular biology may provide the answers.

Ventricular arrhythmias in dilated cardiomyopathy: efficacy of amiodarone

Sixty-five patients with dilated cardiomyopathy were studied by means of 24-hour ECG monitoring. Ventricular arrhythmias were present in 62 (95.4%), of whom 52 (80%) showed a complex form (multiform ventricular extrasystoles, pairs, and ventricular tachycardia). Forty-one patients, presenting with complex ventricular arrhythmias, received antiarrhythmic treatment with amiodarone (600 mg/day in the first week, 400 mg/day in the second week, and 200 to 400 mg/day chronically), and were then controlled with periodic 24-hour ambulatory monitoring. A significant reduction in the number of ventricular extrasystoles was seen in over 70% of patients during a 3-year period. There was also a significant decrease in the incidence of complex ventricular arrhythmias (particularly of ventricular tachycardia). Adverse effects were noted in 23 patients, but only four had to stop treatment. During the follow-up period, 19 patients died: 14 of heart failure, four of sudden death, and one of a noncardiac cause; all patients who died suddenly were not treated with amiodarone (p = 0.022). Complex ventricular arrhythmias are frequent in dilated cardiomyopathy and it is suggested that amiodarone is effective in short- and long-term control of these arrhythmias.

Hormone-electrolyte interactions in the pathogenesis of lethal cardiac arrhythmias in patients with congestive heart failure. Basis of a new physiologic approach to control of arrhythmia

Congestive heart failure is the most arrhythmogenic disorder in cardiovascular medicine. As left ventricular performance deteriorates and symptoms of dyspnea and fatigue become progressively more severe, nearly all patients with heart failure experience frequent and complex ventricular tachyarrhythmias and nearly half die suddenly during long-term follow-up. This imminent risk of sudden death appears to be present for all patients with congestive heart failure; ambulatory electrocardiographic monitoring and programmed electrical stimulation are not useful in distinguishing patient subsets that are particularly predisposed to fatal arrhythmic events. Although conventional antiarrhythmic agents are widely prescribed as a nonspecific approach to prevent sudden death in these patients, there is little evidence to indicate that these drugs possess clinically important antiarrhythmic activity in patients with congestive heart failure, and these agents frequently serve to exacerbate the heart failure state and the underlying ventricular tachyarrhythmia. A useful approach to the prevention of sudden death in patients with congestive heart failure addresses the reversible causes of lethal ventricular arrhythmias in these individuals. Both experimental and clinical evidence indicates that circulating neurohormones and electrolyte deficits (particularly of potassium and magnesium) interact to provoke malignant ventricular ectopic rhythms and that the prevention of electrolyte depletion and the use of neurohormonal antagonists may exert clinically important antiarrhythmic actions. This physiologic approach may prove to be a more effective means of ameliorating the problem of sudden death than the empiric administration of conventional antiarrhythmic drugs.