Arrhythmia risk stratification in idiopathic dilated cardiomyopathy based on echocardiography and 12-lead, signal-averaged, and 24-hour holter electrocardiography

Arrhythmias and cardiac MRI associations in patients with established cardiac dystrophinopathy

AIMS

Some patients with cardiac dystrophinopathy die suddenly. Whether such deaths are preventable by specific antiarrhythmic management or simply indicate heart failure overwhelming medical therapies is uncertain. The aim of this prospective, cohort study was to describe the occurrence and nature of cardiac arrhythmias recorded during prolonged continuous ECG rhythm surveillance in patients with established cardiac dystrophinopathy and relate them to abnormalities on cardiac MRI.

METHODS AND RESULTS

A cohort of 10 patients (36.3 years; 3 female) with LVEF<40% due to Duchenne (3) or Becker muscular (4) dystrophy or Duchenne muscular dystrophy-gene carrying effects in females (3) were recruited, had cardiac MRI, ECG signal-averaging and ECG loop-recorder implants. All were on standard of care heart medications and none had prior history of arrhythmias.No deaths or brady arrhythmias occurred during median follow-up 30 months (range 13-35). Self-limiting episodes of asymptomatic tachyarrhythmia (range 1-29) were confirmed in 8 (80%) patients (ventricular only 2; ventricular and atrial 6). Higher ventricular arrhythmia burden correlated with extent of myocardial fibrosis (extracellular volume%, p=0.029; native T1, p=0.49; late gadolinium enhancement, p=0.49), but not with LVEF% (p=1.0) on MRI and atrial arrhythmias with left atrial dilatation. Features of VT episodes suggested various underlying arrhythmia mechanisms.

CONCLUSIONS

The overall prevalence of arrhythmias was low. Even in such a small sample size, higher arrhythmia counts occurred in those with larger scar burden and greater ventricular volume, suggesting key roles for myocardial stretch as well as disease progression in arrhythmogenesis. These features overlap with the stage of left ventricular dysfunction when heart failure also becomes overt. The findings of this pilot study should help inform the design of a definitive study of specific antiarrhythmic management in dystrophinopathy.

TRIAL REGISTRATION NUMBER

ISRCTN15622536.

Sudden cardiac death markers in non-ischemic cardiomyopathy

Heart failure is an increasingly prevalent disease associated with high morbidity and mortality. In 30-40% of patients, the etiology is non-ischemic. In this group of patients, the implantable cardioverter-defibrillator (ICD) prevents sudden death and decreases total mortality. However, due to burden of cost, the fact that many ICD patients will never need any therapy, and possible complications involved in implant and follow-up, the device should not be implanted in every patient with non-ischemic heart failure. There is an urgent need to adequately identify patients with highest sudden death risk, in whom the implant is most cost-effective. In the present paper, the authors discuss current available tests for risk stratification of sudden cardiac death in patients with non-ischemic heart failure.

Current status of primary prevention of sudden cardiac death with implantable cardioverter defibrillator in patients with chronic heart failure--a report from the CHART-2 Study

BACKGROUND

The current status of primary prevention of sudden cardiac death (SCD) with implantable cardioverter defibrillator (ICD) in patients with heart failure with reduced ejection fraction remains to be fully elucidated in Japan.

METHODS AND RESULTS

In the chronic heart failure (CHF) cohort study, the CHART-2 Study, we enrolled 2,778 consecutive patients with NYHA class II-III. According to the Japanese Circulation Society guideline of prophylactic ICD, we divided them into 3 groups: group A, class I indication; B, class IIa; and C, no indication. During the (median) 3.2-year follow-up, 79 fatal arrhythmic events (FAE), defined as composite of sudden cardiac/arrhythmic death, ventricular tachycardia/fibrillation and appropriate ICD therapy, occurred. In the groups A, B and C, the prevalence of FAE was 16.1%, 8.9% and 1.9%, respectively; the use of prophylactic ICD among those with FAE, however, was only 44%, 9% and 6%, respectively. In the groups A and B combined, chronic atrial fibrillation (cAF) and left ventricular end-diastolic dimension (LVDd) ≥ 65 mm were independent predictors of FAE, and, when combined, their prognostic impact was highly significant (hazard ratio, 7.01; P<0.001).

CONCLUSIONS

Primary prevention of SCD with ICD in CHF patients is validated but is still underused in Japan, and the combination of cAF and LVDd ≥ 65 mm may be a useful indication of prophylactic ICD implantation.

Stratification of the risk of sudden death in nonischemic heart failure

Despite significant therapeutic advancements, heart failure remains a highly prevalent clinical condition associated with significant morbidity and mortality. In 30%-40% patients, the etiology of heart failure is nonischemic. The implantable cardioverter-defibrillator (ICD) is capable of preventing sudden death and decreasing total mortality in patients with nonischemic heart failure. However, a significant number of patients receiving ICD do not receive any kind of therapy during follow-up. Moreover, considering the situation in Brazil and several other countries, ICD cannot be implanted in all patients with nonischemic heart failure. Therefore, there is an urgent need to identify patients at an increased risk of sudden death because these would benefit more than patients at a lower risk, despite the presence of heart failure in both risk groups. In this study, the authors review the primary available methods for the stratification of the risk of sudden death in patients with nonischemic heart failure.

The Relationship between Left Atrial Volume and Ventricular Arrhythmias in the Patients with Dilated Cardiomyopathy

BACKGROUND

The present study aimed to investigate the relationship between Left Atrial Volume (LAV), a marker of diastolic dysfunction, and the frequency of malignant ventricular arrhythmia in the patients with left ventricular dysfunction and a previously implanted Implantable Cardioverter Defibrillator (ICD) device.

METHODS

This cross-sectional study was conducted on 32 patients with ischemic or idiopathic dilated cardiomyopathy, each having had an ICD device implanted at least 1 year beforehand. The ventricular arrhythmia episodes which were detected and stored by the device were retrieved and evaluated. In addition to routine echocardiographic measurements, all the patients had their LAV and LAV indexes calculated. After all, student's t-test, Mann-Whitney U test, and Pearson correlation were used to analyze the data. Besides, P value < 0.05 was considered as statistically significant.

RESULTS

This study was conducted on 4 female and 28 male patients with the mean age of 58.41 ± 9.97 years. Among the study patients, 21 had at least one previous myocardial infarction. In addition, 17 patients had experienced sustained VT or VF within the last year. No significant difference was found between the patients with and without malignant ventricular arrhythmias (sustained VT or VF) regarding LAV (17 patients with arrhythmia (68 + 23.39 mL) vs. 15 patients without arrhythmia (55.13 ± 20.41 mL); P = 0.100). However, the LAV index was significantly higher in the patients with arrhythmia compared to those without arrhythmia (39.27 ± 12.19 mL / m2 vs. 25.18 ± 7.45 mL / m2; P = 0.004). Both LAV (73.33 ± 17.64 mL and 57.52 ± 23.15 mL, respectively; P = 0.040) and LAV index (40.86 ± 8.47 mL / m2 and 28.20 ± 11.77 mL / m2, respectively; P = 0.010) were significantly greater in the patients with ICD shock therapy within the last year compared to the others. However, both groups were similar regarding Left Ventricular Volume (LVV), LVV index, and ejection fraction.

CONCLUSIONS

The study findings demonstrated that LAV and LAV index could be used in detecting the patients who are at high risk of malignant ventricular arrhythmias.

Primary prevention of sudden cardiac death in a nonischemic dilated cardiomyopathy population: reappraisal of the role of programmed ventricular stimulation

BACKGROUND

We considered the role of programmed ventricular stimulation in primary prevention of sudden cardiac death in an idiopathic dilated cardiomyopathy population.

METHODS AND RESULTS

One hundred fifty-eight patients with idiopathic dilated cardiomyopathy underwent programmed ventricular stimulation. Ventricular tachycardia/ventricular fibrillation was triggered in 44 patients (group I, 27.8%) versus 114 patients (group II), where ventricular tachycardia/ventricular fibrillation was not induced. Sixty-nine patients with idiopathic dilated cardiomyopathy underwent implantable cardioverter-defibrillator (ICD) implantation: 41/44 in group I and 28/114 in group II. The major end points of the study were overall mortality and appropriate ICD activation. Overall mortality during the 46.9 months of mean follow-up was not significantly different between the 2 groups. Patients with left ventricular ejection fraction ≤35% (n=119) demonstrated a higher overall mortality rate compared with the patients with left ventricular ejection fraction >35% (n=39; 16.8% versus 10.3%, log-rank P=0.025). Advanced New York Heart Association class (III and IV versus I and II) was the single independent and strongest prognostic factor of overall mortality (hazard ratio, 11.909; P<0.001; confidence interval, 3.106-45.65), as well as of cardiac mortality (hazard ratio, 14.787; P=0.001; confidence interval, 2.958-73.922). Among ICD recipients, ICD activation rate was significantly higher in group I compared with group II (30 of 41 patients-73.2% versus 5 of 28 patients-17.9%; log-rank P=0.001), either in the form of antitachycardia pacing (68.3% versus 17.9%; log-rank P=0.001) or in the shock delivery form (51.2% versus 17.9%; log-rank P=0.05). Induction of ventricular tachycardia/ventricular fibrillation during programmed ventricular stimulation in contrast to left ventricular ejection fraction was the single independent prognostic factor for future ICD activation (hazard ratio, 4.195; P=0.007; confidence interval, 1.467-11.994).

CONCLUSIONS

Inducibility of ventricular tachycardia/ventricular fibrillation was associated with an increased likelihood of subsequent ICD activation and sudden cardiac death surrogate.

Effect of corticosteroid therapy on ventricular arrhythmias in patients with cardiac sarcoidosis

BACKGROUND

Ventricular arrhythmias are one of the main causes of sudden death in cardiac sarcoidosis (CS). Little is known about the efficacy of corticosteroid therapy for ventricular arrhythmias in CS.

METHODS

Thirty-one CS patients presenting premature ventricular contractions (PVCs, ≥300/day) were investigated. Fourteen patients had nonsustained ventricular tachycardia (NSVT). All of patients were treated with corticosteroid, and the initial dosage is 30 mg/day of prednisone, which was tapered over a period of 6 months to a maintenance dosage of 10 mg/day. Twenty-four hour Holter monitoring, signal averaged electrocardiography (SAECG), echocardiography, gallium-67 scintigraphy, serum angiotensin converting enzyme (ACE) and plasma B-type natriuretic peptide (BNP) concentrations were assessed before and after corticosteroid therapy.

RESULTS

As a whole, there were no significant differences in the number of PVCs and in the prevalence of NSVT before and after steroid therapy. However, the less advanced LV dysfunction patients (EF ≥ 35%, n = 17) showed significant reduction in the number of PVCs (from 1820 ± 2969 to 742 ± 1425, P = 0.048) and in the prevalence of NSVT (from 41 to 6%, p = 0.039). Late potentials on SAECG were abolished in 3 patients. The less advanced LV dysfunction group showed a significantly higher prevalence of gallium-67 uptake compared with the advanced LV dysfunction group (EF < 35 %, n = 14). In the advanced LV dysfunction patients, there were no significant differences in these parameters.

CONCLUSIONS

Corticosteroid therapy may be effective for ventricular arrhythmias in the early stage, but less effective in the late stage.

The management of myocarditis

Despite considerable advances in our understanding of myocarditis pathogenesis, the clinical management of myocarditis has changed relatively little in the last few years. This review aims to help bridge the widening gap between recent mechanistic insights, which are largely derived from animal models, and their potential impact on disease burden. We illustrate the pathogenetic mechanisms that are prime targets for novel therapeutic interventions. Pathway and pathogen-specific molecular diagnostic tests have expanded the role for endomyocardial biopsy. State of the art cardiac magnetic resonance imaging can now provide non-invasive tissue characterization and localize inflammatory infiltrates but imaging techniques are misleading if infectious agents are involved. We emphasize the gaps in our current clinical knowledge, particularly with respect to aetiology-based therapy, and suggest opportunities for high impact, translational investigations.

[Long term electrocardiography (Holter monitoring)]

During the past almost 50 years Holter monitoring has become an established non-invasive diagnostic tool in clinical electrophysiology. It allows ECG recording independent of stationary monitoring facilities during daily life and, therefore, contains much information. In the beginning the main interest was directed towards quantitative and qualitative assessment of arrhythmias, their circadian behaviour, and the circadian behaviour of the heart rate. With advances in technology the analysis spectrum of Holter monitoring expanded, and it was used also for detection of silent myocardial ischaemia. New digital recorders and computers with large capacities made it possible to measure every single heart beat very accurately, which was a prerequisite for heart rate variability and QT-interval analysis, which provided new knowledge about the autonomic modulation of the heart rate and the circadian dynamicity of the QT interval, respectively. Beyond arrhythmia analysis Holter monitoring was increasingly used to assess prognosis in different cardiac conditions. It can also be valuable in assessing transient symptoms possibly related to arrhythmias or device dysfunction, which will not necessarily be revealed by simple device control.

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.

Elevated B-type natriuretic peptide levels in patients with nonischemic cardiomyopathy predict occurrence of arrhythmic events

BACKGROUND

Patients with nonischemic cardiomyopathy (DCM) are at high risk for sudden cardiac death (SCD). However, the predictive value of prophylactic implantation of implantable cardioverter defibrillators (ICD) in this patient cohort is yet unclear.

METHODS AND RESULTS

Whether NT pro BNP levels and/or reproducible non sustained ventricular tachycardias (NSVTs) are predictive for SCD was prospectively tested in 30 patients with DCM and LVEF </= 40%. All patients received Holter-recordings (HR) on three consecutive days and baseline NT-pro BNP levels were determined. Patients were followed for occurrence of ventricular tachyarrhythmias or unexplained syncope. A great degree of variability was found regarding the occurrence of NSVTs (10% had NSVTs in two consecutive HR, 10% in three consecutive HR, 30% in one HR and 50% had no NSVTs). Patients with NSVTs in more than one HR had significantly higher NT-pro BNP levels (first quartile: 715 pg/ml, median 2,176 pg/ml, third quartile 5,755 pg/ml vs. first quartile 273 pg/ml, median 566 pg/ml, third quartile 1,350 pg/ml, P = 0.0388). During a mean follow-up of 21.6 +/- 1.2 months patients with an arrhythmic event had significantly higher NT-pro BNP levels than patients without event (first quartile: 1,002 pg/ml, median 4,075 pg/ml, third quartile 7,777 pg/ml vs. first quartile 173 pg/ml, median 267 pg/ml, third quartile 1,220 pg/ml, P = 0.0135). NT-pro BNP levels of 2,259 pg/ml were identified as optimal cut-off value for the prediction of arrhythmic events (P = 0.0313). In contrast reproducible NSVTs were not predictive for arrhythmic events (P = 0.0960).

CONCLUSION

The present study demonstrates that in patients with DCM the value of reproducible NSVTs in predicting arrhythmic events is low. In contrast raised NT-pro BNP levels significantly correlated with occurrence of symptomatic ventricular arrhythmias. Larger prospective trials are required to confirm these results.

Influence of antiarrhythmia therapy on survival times of 19 clinically healthy Doberman pinschers with dilated cardiomyopathy that experienced syncope, ventricular tachycardia, and sudden death (1985-1998)

Overtly healthy Doberman pinschers, having moderate to severe myocardial failure secondary to dilated cardiomyopathy, which experienced ventricular tachycardia, syncope or collapse, and sudden death were studied to determine the effect of antiarrhythmic medication on their clinical outcome. Antiarrhythmia drug therapy may have retarded sudden death in 13 treated dogs compared to the six dogs not administered antiarrhythmia drugs.

Prophylactic implantable cardioverter defibrillator therapy in dilated cardiomyopathy: Impact of left ventricular function

BACKGROUND

The value of an implantable cardioverter defibrillator (ICD) for primary prevention in dilated cardiomyopathy (DCM) is unclear, as randomized trials could not show a survival benefit compared to drug therapy. It has not been investigated if patients with a very poor left ventricular function (LVEF) could profit from an ICD.

METHODS

Consecutive patients with DCM who received an ICD between December 1996 and November 2003 were included in this analysis. Patients were divided in group A (secondary prevention) and group B (primary prevention). Both groups were stratified in subgroups with left ventricular ejection fraction (LVEF) below and above 20%.

RESULTS

Fifty eight patients were included (male 50, age 56.4+/-12.7 years). Follow-up was 34+/-19 months. There was no difference regarding death (18% vs. 11%), but significant differences (p value <0.05) regarding any adverse events (55% vs. 22%), any ICD intervention (48% vs. 17%) and ICD interventions for life-threatening arrhythmias (27% vs. 0%) between group A and B. LVEF was not predictive for events in group A, whereas in group B only patients with a LVEF <20% had events (p value 0.02). Over time there was an increase of the LVEF of more than 15% determined by echocardiography in 36% of patients, significantly more often in group B.

CONCLUSIONS

Indication for primary prevention with an ICD in DCM should be made with caution. Larger studies are needed to determine if patients with LVEF of <20% might benefit from an ICD.

Long-term continuous external electrocardiographic recording: a review

Ambulatory electrocardiographic (AECG) monitoring is an essential tool in the diagnostic evaluation of patients with cardiac arrhythmias. Recent advances in solid-state technology have improved the quality of the ECG signals and new dedicated algorithms have expanded the clinical application of software-based AECG analysis systems. These advances, in addition to the availability of inexpensive large storage capacities, and very long-term continuous high-quality AECG monitoring, have opened new potential uses for AECG. New digital recorders have the capability of multichannel simultaneous recordings (from 3 to 12 leads) and for telemetred signal transduction. These possibilities will expand the traditional uses of AECG for arrhythmia detection, as arrhythmia monitoring to assess drug and device efficacies has been further defined by new studies. The analysis of transient ST-segment deviation still remains controversial, but considerably more data are now available, especially about the prognostic value of detecting asymptomatic ischaemia. Heart rate variability analysis has shown promise for predicting mortality rates in cardiac patients at high risk. We review recent advances in this field of non-invasive cardiac testing.

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.

T wave spectral variance for noninvasive identification of patients with idiopathic dilated cardiomyopathy prone to ventricular fibrillation even in the presence of bundle branch block or atrial fibrillation

Conventional methods using Holter ECG recordings for noninvasive risk stratification are limited in patients with idiopathic dilated cardiomyopathy (IDC) prone to ventricular fibrillation (VF) having atrial fibrillation (AF) or bundle branch block (BBB). We therefore investigated, whether spectral assessment of beat-to-beat alternations of repolarization is associated with VF in these patients. Twenty-four-hour Holter ECG recordings in 462 patients with IDC were used. The VF group comprised of 64 consecutive patients who survived cardiac arrest, the no VF group consisted of 398 consecutive patients without a history of malignant ventricular arrhythmia. One hundred patients with ischemic cardiomyopathy (ICM) served as a control group. In each patient, 1,024 consecutive T waves were aligned using cross correlation methods. Two-dimensional Fourier transform (2D FFT) used the data matrix of 1,024 consecutive 200-ms segments centered to the T wave peak. Power spectra of the 2D FFT revealed the frequency content of the T wave in the first dimension and the periodicity of this frequency content in the second dimension. The ratio between periodic frequency contents and the sum of nonperiodic and periodic frequency contents between 0.5 and 50 Hz is equal to the T wave spectral variance (TWSV) index. Thus, TWSV index = 0 would mean that all 1,024 T waves are identical and TWSV index = 1 would mean that the 1,024 T waves are totally variable. The TWSV index was significantly higher in the VF group (0.93 +/- 0.14) than in the no VF group (0.53 +/- 0.13, P < 0.01). The best cutoff between the VF and the no VF group was achieved by using a TWSV index of 0.75 (sensitivity = 89%, specificity = 78%). No significant differences were observed between patients with and without AF or with and without BBB, and between patients with IDC and ICM. Even in the presence of BBB or AF spectral assessment of T wave alternations by TWSV index using 2D FFT in Holter ECG recordings, allows the identification of patients with IDC at risk for VF.

Cholinergic stimulation with pyridostigmine reduces ventricular arrhythmia and enhances heart rate variability in heart failure

BACKGROUND

Increased ventricular arrhythmia density and reduced heart rate variability are associated with risk of death in patients with heart failure. Cholinesterase inhibition with pyridostigmine bromide increases heart rate variability in normal subjects, but its effect on patients with heart failure is unknown. In this study, we tested the hypothesis that short-term administration of pyridostigmine bromide, a cholinesterase inhibitor, reduces ventricular arrhythmia density and increases heart rate variability in patients with congestive heart failure.

METHODS

Patients with heart failure and in sinus rhythm participated in a double-blind, cross-over protocol, randomized for placebo and pyridostigmine (30 mg orally 3 times daily for 2 days). Twenty-four hour electrocardiographic recordings were performed for arrhythmia analysis and for the measurement of time domain indices of heart rate variability. Patients were separated into 2 groups, according to their ventricular arrhythmia density. The arrhythmia group (n = 11) included patients with >10 ventricular premature beats (VPBs) per hour (VPBs/h), and the heart rate variability group (n = 12) included patients with a number of VPBs in 24 hours not exceeding 1% of the total number of R-R intervals.

RESULTS

For the arrhythmia group, pyridostigmine resulted in a 65% reduction of ventricular ectopic activity (placebo 266 +/- 56 VPBs/h vs pyridostigmine 173 +/- 49 VPBs/h, P =.03). For the heart rate variability group, pyridostigmine administration increased mean R-R interval (placebo 733 +/- 22 ms vs pyridostigmine 790 +/- 33 ms, P =.01), and in the time domain indices of heart rate variability root-mean-square of successive differences (placebo 21 +/- 2 ms vs pyridostigmine 27 +/- 3 ms, P =.01) and percentage of pairs of adjacent R-R intervals differing by >50 ms (placebo 3% +/- 1% vs pyridostigmine 6% +/- 2%, P =.03).

CONCLUSION

In patients with heart failure, pyridostigmine reduced ventricular arrhythmia density and increased heart rate variability, most likely due to its cholinomimetic effect. Long-term trials with pyridostigmine in heart failure should be conducted.

Prognostic significance of heart rate turbulence following ventricular premature beats in patients with idiopathic dilated cardiomyopathy

Heart Rate Turbulence in Dilated Cardiomyopathy.

INTRODUCTION

The aim of this study was to investigate the prognostic significance of heart rate turbulence (HRT) characterized by HRT onset and slope after ventricular premature beats in patients with idiopathic dilated cardiomyopathy (IDC).

METHODS AND RESULTS

Blinded HRT analysis was performed in 242 patients with IDC who were enrolled in the Marburg Cardiomyopathy database between 1992 and 2000. During 41 +/- 23 months of follow-up, 54 patients (22%) died or underwent heart transplant. On Cox univariate regression analysis, abnormal HRT onset, HRT slope, HRT onset combined with HRT slope, left ventricular (LV) ejection fraction, LV size, and New York Heart Association (NYHA) functional class III showed a significant association with total mortality or the need for heart transplant. On multivariate analysis, abnormal HRT onset identified patients without transplant-free survival, as did LV size and NYHA class III heart failure. Major arrhythmic events were observed in 42 patients (17%) during follow-up. On univariate analysis, abnormal HRT onset, HRT onset combined with HRT slope, male sex, NYHA class III, LV ejection fraction, and LV size were associated with a higher incidence of major arrhythmic events. On multivariate analysis, only LV ejection fraction remained as a significant arrhythmia risk predictor, with a relative risk of 2.2 per 10% decrease in ejection fraction (95% confidence interval 1.5-3.2).

CONCLUSION

In this selected patient population with IDC, HRT onset is a significant predictor of transplant-free survival, as are LV size and NYHA class. For arrhythmia risk stratification, however, only LV ejection fraction remained a significant risk predictor on multivariate analysis.

Implantable defibrillator event rates in patients with idiopathic dilated cardiomyopathy, nonsustained ventricular tachycardia on Holter and a left ventricular ejection fraction below 30%

OBJECTIVES

This study investigated the incidence of appropriate implantable cardioverter defibrillator (ICD) interventions for ventricular tachycardia (VT) or ventricular fibrillation (VF) in patients with idiopathic dilated cardiomyopathy (IDC) and nonsustained VT in the presence of a left ventricular ejection fraction below 30%, versus in patients with syncope and patients with a history of VT or VF.

BACKGROUND

To date, only limited information is available about the prophylactic use of ICDs in patients with IDC.

METHODS

From January 1993 to July 2000, 101 patients with IDC underwent implantation of ICDs with electrogram storage capability at our institution. Patients were placed into one of three groups according to their clinical presentation: asymptomatic or mildly symptomatic nonsustained VT in the presence of a left ventricular ejection fraction < or = 30% (49 patients, prophylactic group), unexplained syncope or near syncope (26 patients, syncope group) and a history of sustained VT or VF (26 patients, VT/VF group).

RESULTS

During 36 +/- 22 months follow-up, 18 of 49 patients (37%) in the prophylactic group received appropriate shocks for VT or VF, compared with 8 of 26 patients (31%) in the syncope group and with 9 of 26 patients (35%) of the VT/VF group. Multivariate Cox analysis of baseline clinical variables identified left ventricular ejection fraction, atrial fibrillation and a history of sustained VT or VF as predictors for appropriate ICD interventions during follow-up.

CONCLUSIONS

Patients with IDC and prophylactic ICD implantation for nonsustained VT in the presence of a left ventricular ejection fraction < or = 30% had an incidence of appropriate ICD interventions similar to that of patients with a history of syncope or sustained VT or VF. These findings indicate that ICDs may have a role in not only secondary but also primary prevention of sudden death in IDC.

Onset heart rate of microvolt-level T-wave alternans provides clinical and prognostic value in nonischemic dilated cardiomyopathy

OBJECTIVES

This study was designed to determine the prognostic value of onset heart rate (OHR) in T-wave alternans (TWA) in patients with nonischemic dilated cardiomyopathy (DCM).

BACKGROUND

One of the current major issues in DCM is to prevent sudden cardiac death (SCD). However, the value of the OHR of TWA as a prognostic indicator in DCM remains to be elucidated.

METHODS

We prospectively investigated 104 patients with DCM undergoing TWA testing. The end point of this study was defined as SCD, documented sustained ventricular tachycardia/ventricular fibrillation. Relations between clinical parameters and subsequent outcome were evaluated.

RESULTS

Forty-six patients presenting with TWA were assigned to one of the following two subgroups according to OHR for TWA of < or = 100 beats/min: group A (n = 24) with OHR < or = 100 beats/min and group B (n = 22) with 100 < OHR < or = 110 beats/min. T-wave alternans was negative in 37 patients (group C) and indeterminate in 21 patients. The follow-up result comprised 83 patients with determined TWA. During a follow-up duration of 21 +/- 14 months, there was a total of 12 arrhythmic events, nine of which included three SCDs in group A, two in group B and one in group C. The forward stepwise multivariate Cox hazard analysis revealed that TWA with an OHR < or = 100 beats/min and left ventricular ejection fraction were independent predictors of these arrhythmic events (p = 0.0001 and p = 0.0152, respectively).

CONCLUSIONS

The OHR of TWA is of additional prognostic value in DCM.

Cardiomyopathies: from genetics to the prospect of treatment

Cardiomyopathies are defined as diseases of the myocardium associated with cardiac dysfunction ranging from lifelong symptomless forms to major health problems such as progressive heart failure, arrhythmia, thromboembolism, and sudden cardiac death. They are classified by morphological characteristics as hypertrophic (HCM), dilated (DCM), arrhythmogenic right ventricular (ARVC), and restrictive cardiomyopathy (RCM). A familial cause has been shown in 50% of patients with HCM, 35% with DCM, and 30% with ARVC. In HCM, nine genetic loci and more than 130 mutations in ten different sarcomeric genes and in the gamma 2 subunit of AMP-activated protein kinase (AMPK) have been identified, suggesting impaired force production associated with inefficient use of ATP as the crucial disease mechanism. In DCM, 16 chromosomal loci with defects of several proteins also involved in the development of skeletal myopathies have been detected. These mutated cytoskeletal and nuclear transporter proteins may alter force transmission or disrupt nuclear function, resulting in cell death. Further DCM mutations have also been identified in sarcomeric genes, which indicates that different defects of the same protein can result in either HCM or DCM. In ARVC, six genetic loci and mutations in the cardiac ryanodine receptor, which controls electromechanical coupling, and in plakoglobin and desmoglobin (molecules involved in desmosomal cell-junction integrity), have been identified. Yet, no genetic linkage has been shown in RCM. Apart from disease-causing mutations, other factors, such as environment, genetic background, and the recently identified modifier genes of the renin-angiotensin, adrenergic, and endothelin systems are likely to result in the wide variety of RCM clinical presentations. Treatment options are symptomatic and are mainly focused on treatment of heart failure and prevention of thromboembolism and sudden death. Identification of patients with high risk for major arrhythmic events is important because implantable cardioverter defibrillators can prevent sudden death. Clinical and genetic risk stratification may lead to prospective trials of primary implantation of cardioverter defibrillators in people with hereditary cardiomyopathy.