Left ventricular diastolic pulsus alternans in hypertrophic cardiomyopathy

Summary We examined left ventricular (LV) diastolic pulsus alternans associated with systolic pulsus alternans in a patient with hypertrophic cardiomyopathy. Alternation in abnormal LV diastolic pressure waveforms persistently declining into mid-diastole (incomplete relaxation) and normal diastolic pressure were noted. Diastolic pulsus alternans was not corrected by isoproterenolol and may possibly be independent of systolic pulsus alternans.     

Noninvasive findings in patients with hypertrophic and dilative cardiomyopathy: a combined echocardiographic and radionuclide angiographic study

Fifteen patients with hypertrophic (HCM) and 15 with dilative cardiomyopathy (DCM) were examined with radionuclide angiography and M-mode echocardiography to evaluate the combination of two noninvasive methods for measuring left ventricular performance. The patients with HCM had delayed myocardial relaxation and rapid filling time with preserved peak rate of early ventricular filling. DCM patients, on the contrary, had low values of left ventricular systolic performance and low peak filling rate. Myocardial relaxation and rapid filling time, however, were short, indicating compensatory mechanisms in the failing ventricle improving rapid filling.     

Clinical significance of early diastolic time intervals for the differentiation of idiopathic dilative cardiomyopathy from ischemic cardiomyopathy

In order to differentiate idiopathic dilative cardiomyopathy from ischemic cardiomyopathy noninvasively, systolic time intervals (STIs) and early diastolic time intervals were investigated in patients with idiopathic dilative cardiomyopathy (n = 11), patients with ischemic cardiomyopathy (n = 8), and normal controls (n = 17). Minimal left ventricular pressure and pulmonary capillary wedge pressure (PCWP) were also measured to clarify the relationship between early diastolic time intervals and early diastolic hemodynamics. Cardiac function estimated by STIs was markedly depressed both in idiopathic dilative cardiomyopathy and ischemic cardiomyopathy, and there was no difference between the two diseases. In early diastolic time intervals, IIA-O time (the interval from the aortic component of the second heart sound to the O point of apexcardiogram) was significantly prolonged both in idiopathic dilative cardiomyopathy (144 +/- 31 (SD); p less than 0.01) and ischemic cardiomyopathy (153 +/- 15; p less than 0.01) compared to normal controls (126 +/- 11). IIA-MVO time (the interval from IIA to the mitral valve opening) in idiopathic dilative cardiomyopathy (49 +/- 23) was significantly shorter than that in normal controls (70 +/- 8; p less than 0.05). On the contrary, IIA-MVO time in ischemic cardiomyopathy (126 +/- 11) was markedly prolonged compared with normal controls (p less than 0.01) and idiopathic dilative cardiomyopathy (p less than 0.01). MVO-O time was significantly prolonged in idiopathic dilative cardiomyopathy (94 +/- 18; p less than 0.01). However, it was conversely shortened in ischemic cardiomyopathy (25 +/- 15) compared with normal controls (54 +/- 7; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise-induced quantitative microvolt T-wave alternans in hypertrophic cardiomyopathy

Background/Purpose

Patients with hypertrophic cardiomyopathy (HCM) have elevated risk for sudden cardiac death (SCD). Our study aimed to quantitatively characterize microvolt T-wave alternans (TWA), a potential arrhythmia risk stratification tool, in this HCM patient population.

扩张型心肌病患者微伏级T波电交替检测分析

目的研究扩张型心肌病患者微伏级T波电交替(MTWA)的发生情况及与心率的关系。方法对31例扩张型心肌病患者用频谱法检测MTWA,分析扩张型心肌病MTWA的阳性率及不确定结果的原因,静息和运动时MTWA的发生情况,心率与交替压(Valt)的关系。结果①扩张型心肌病患者MTWA的阳性率为35.48%;②扩张型心肌病者,运动时的心率大于静息时,运动时各导联的Valt值大于静息时(P均<0.01)。静息时MTWA阳性2例,运动时MTWA阳性11例,运动时MTWA的阳性率高于静息时(35.48%vs 6.45%,P<0.01);③心率与综合导联Valt呈正相关,随心率的增加,Valt增大(r=0.984,P<0.01)。结论①扩张型心肌病患者MTWA阳性率高于正常人;②MTWA的发生与心率相关,随心率增快,Valt增大,MTWA阳性检出率增加。     

Comparative analysis of myocardial enzyme activities of the energy-supplying metabolism in patients with dilative cardiomyopathies and valve diseases

We determined representative enzyme activities of glycogenolysis (glycogen phosphorylase) glycolysis (d-glyceraldehyde-3-phosphate dehydrogenase, GAPDH), beta oxidation of free fatty acids (1-3-hydroxyacyl CoA dehydrogenase, HADH), citric acid cycle (citrate synthase, CS), lactate fermentation (lactate dehydrogenase LDH), and creatine phosphate metabolism (creatine kinase, CK) in left ventricular samples of 36 patients to investigate if the metabolic capacities of the energy-supplying pathways are differently affected in different heart diseases. There were 17 patients with mitral valve diseases (MVD), 8 patients with aortic valve diseases (AVD), and 11 patients who suffered from dilative cardiomyopathies (DCM). The main metabolic characteristic on the level of enzymatic organization in patients with DCM was an increased ratio of GAPDH/HADH activities and a decreased ratio of HADH/CS activities compared to the valve-diseased patients. This result indicates that the capacity of glucose oxidation is enhanced at the expense of fatty acid metabolism in patients with DCM. Furthermore, we determined significantly lower myocardial CK activities in this group of patients, most probably reflecting a diminished content of myofibrils. Citrate synthase activity was lowest in patients with AVD. Although we cannot rule out that the impaired left ventricular function is in part responsible for the shift of the capacities of the energy-supplying metabolism in patients with DCM, we favor the assumption that it is a specific feature of this myocardial disease.     

Quantitative assessment of microvolt T-wave alternans in patients with congestive heart failure

INTRODUCTION: T-wave alternans has been shown to be linked to the genesis of ventricular tachyarrhythmias. Currently, only qualitative assessment of microvolt T-wave alternans (MTWA) is recommended in clinical practise. Whether quantitative assessment of MTWA yields complementary information is unknown. METHODS AND RESULTS: Noninvasive MTWA determination was performed in 204 consecutive patients with ischemic or nonischemic cardiomyopathy. Of those, 100 tested MTWA positive. In these recordings, MTWA magnitude was quantitatively assessed (alternans voltage, V(alt)). Patients were followed for a mean of 17 months. Ventricular tachyarrhythmic events constituted the study endpoint. Patients with nonischemic cardiomyopathy had a higher V(alt) than patients with ischemic cardiomyopathy (10.3 +/- 9.2 [median 7.2] vs 6.2 +/- 3.2 [median 4.6] microV; P = 0.007). The number of MTWA-positive ECG leads was also higher in patients nonischemic cardiomyopathy (7.3 +/- 2.4 [median 8] vs 6.0 +/- 2.5 [median 6]; P = 0.016). Patients who suffered an arrhythmic event during follow-up had higher MTWA voltages (10.8 +/- 10.0 [median 8.8] vs 7.4 +/- 5.7 [median 6.4] microV; P = 0.05) a higher number of MTWA-positive ECG leads (7.6 +/- 2.4 [median 8] vs 6.4 +/- 2.5 [median 6]; P = 0.05) compared to patients with an uncomplicated course. CONCLUSION: Patients with nonischemic cardiomyopathy and patients with tachyarrhythmic complications have more extensive MTWA possibly reflecting more extensive myocardial damage and a higher arrhythmia propensity.     

The myocardial oxygen supply/demand ratio in patients with and without coronary artery disease

This study was performed to assess the relationship between coronary sinus blood flow (by thermodilution) and myocardial oxygen demand (heart rate-systolic arterial pressure double product) during atrial pacing in patients with and without coronary artery disease. In 11 individuals with coronary artery disease, pacing was performed to ischemia, as reflected by electrocardiographic changes or lactate production; 8 patients without coronary artery disease served as controls. Coronary sinus blood flow (in ml/min) was similar for the two groups at rest. However, the increase in coronary blood flow from rest to peak pacing was less (P = 0.025) in those with coronary artery disease (50 ± 26 ml/min) than in controls (79 ± 26 ml/min). The ratio of coronary sinus blood flow to double product was the same at rest in both groups (11.1 ± 2.2 × 10^?3 controls, 11.6 ± 2.7 × 10^?3 coronary artery disease; NS). At peak pacing, it was unchanged in the controls (10.4 ± 2.0 × 10^?3) but fell in those with coronary artery disease (9.0 ± 2.5 × 10^?3; P = 0.002). The aortic-coronary sinus oxygen content difference was similar at rest in both groups and did not change in response to pacing in either group. Thus, in response to augmented myocardial oxygen demand, patients without coronary artery disease have an appropriate increase in coronary blood flow and myocardial oxygen supply, while in those with coronary artery disease who develop ischemia the increment in myocardial blood flow (and oxygen supply) is inappropriately low.     

Linkage between mechanical and electrical alternans in patients with chronic heart failure

INTRODUCTION: Progressive heart failure and ventricular fibrillation are major causes of death in patients with chronic heart failure. Mechanical alternans (pulsus alternans) has been observed in patients with severe congestive heart failure. Visible T wave alternans occasionally is a precursor of ventricular fibrillation. We investigated the occurrence of both cardiac alternans in 94 patients with chronic heart failure. Methods AND RESULTS: Mean left ventricular ejection fraction (LVEF) of the study population was 35 +/- 10%. Mechanical alternans was detected in left ventricular pressure during diagnostic cardiac catheterization. Only sustained mechanical alternans was included in the study. Visible T wave alternans, not microvolt alternans, was noted on standard surface ECG. Cardiac alternans was examined at rest, during physiologic tachycardia, and during stepwise dobutamine loading (2-4-8 microg/kg/min). Prevalences of mechanical and electrical alternans were 19.1% and 4.4% at rest, 45.5% and 8.0% during physiologic tachycardia, and 62.1% and 9.5% under dobutamine loading. Overall, 70 patients (74.5%) showed mechanical alternans and 10 patients (10.6%) showed T wave alternans. T wave alternans always appeared with large mechanical alternans. Among patients with mechanical alternans, cases with T wave alternans showed lower LVEF than those without (27.5 +/- 4.4 and 35.1 +/- 10.2, P < 0.002). CONCLUSION: Visible T wave alternans was detectable in patients with chronic heart failure, especially under tachycardia or catecholamine exposure. Investigating mechanical and mechanoelectrical alternans may bring new insights into the management of patients with chronic heart failure.     

Predictive value of microvolt T-wave alternans for cardiac death or ventricular tachyarrhythmic events in ischemic and nonischemic cardiomyopathy patients: a meta-analysis

Background: Microvolt T‐wave alternans (MTWA) has been proposed as a predictor of the risk of ventricular tachyarrhythmias (VT) and sudden cardiac death (SCD). Aim of this study was to perform a systematic review of the literature and a meta‐analysis of MTWA in primary prevention patients with ischemic and nonischemic cardiomyopathy. Methods: The positive predictive value (PPV), negative predictive value (NPV), and relative risk (RR) of MTWA in predicting death, cardiac death, and SCD during follow‐up were reported. Results: Fifteen studies involving 5681 patients (mean age 62 years, mean ejection fraction 32%) were included. The summary PPV during the average 26‐month follow‐up was 14% (95% CI: 13–15); NPV was 95% (95% CI: 94–96), and the univariate RR was 2.35 (95% CI: 1.68–3.28). The predictive value of MTWA was similar in patients with ischemic and nonischemic cardiomyopathy. The average RR for SCD or VT events of an abnormal MTWA was 2.40, similar to that for cardiac death. When we grouped the studies together depending upon whether beta‐blockers were withheld prior to MTWA screening, the beta‐blockers group showed an RR of 5.88. By contrast, the group in which beta‐blocker therapy was withheld had an RR of 1.63. Conclusion: A positive MTWA determined an approximately 2.5‐fold higher risk of cardiac death and life‐threatening arrhythmia and showed a very high NPV both in ischemic and nonischemic patients. An abnormal MTWA test was associated with a 5‐fold increased risk for cardiac mortality in the low‐indeterminate group and about a 6‐fold increased risk in beta‐blockers group. Ann Noninvasive Electrocardiol 2011;16(4):388–402     

Disopyramide improves the balance between myocardial oxygen supply and demand in patients with hypertrophic obstructive cardiomyopathy

Summary We evaluated the effects of disopyramide in terms of the balance between myocardial oxygen supply and demand in patients with hypertrophic obstructive cardiomyopathy (HOCM). The myocardial oxygen supply was evaluated by measuring coronary flow velocity and the myocardial oxygen demand was assessed by the pressure-volume area (PVA). The time velocity integral of coronary flow did not change significantly (20±6 to 21±8 cm), but the peak left ventricular pressure and left ventricular external work decreased significantly (206±44 to 157±37 mmHg,P<0.001; 1.09±0.33 to 0.80±0.23 J/beat,P<0.001) after disopyramide administration. From theoretical analysis using these data, we concluded that disopyramide improves the myocardial oxygen supply-demand balance in patients with HOCM.     

急性心肌梗死后患者不同时间的微伏级T波电交替

目的观察急性心肌梗死(简称心梗)后不同时间的微伏级T波电交替(MTWA)。方法用带有TWA移动平均修正技术(TWA MMA)的动态心电图检测系统,以时域法检测45例急性心梗后患者小于1个月、6个月时MTWA。判断标准是:在V3导联Val≥t47μV为阳性,Val≤t47μV为阴性。2次检测均为阴性的归为A组;2次检测,其中1次为阳性的归为B组。结果小于1个月时MTWA阴性占80%,阳性占20%;6个月时MTWA阴性占60%,阳性占40%;6个月时有11例(24.4%)MTWA由阴性转变为阳性,有3例(6.7%)由阳性转变为阴性。这两个时期检测MTWA,结果一致的病人有29例,符合率为64.4%。阴性转阳性患者左室射血分数降低多于持续阴性患者。结论急性心梗后6个月内MTWA处于动态变化之中,对急性心梗后6个月内,MTWA阴性的患者应予更多的关注。     

Microvolt T-wave alternans for risk stratification of cardiac events in ischemic cardiomyopathy: A meta-analysis

Background

The ability of microvolt T-wave alternans (MTWA) for risk stratification of cardiac events in patients with ischemic cardiomyopathy (ICM) has not been well established.

Methods

The authors systematically reviewed current literature and carried out a meta-analysis to determine the ability of MTWA to predict the outcome severity after ICM. Major endpoints include composite endpoint of cardiac mortality and severe arrhythmic events in primary prevention of patients with ICM, as well as all-cause mortality (cardiac death, and/or non-cardiac death).

Results

Seven trials were included by using MTWA for risk stratification of cardiac events in 3385 patients with ICM. All patients were distributed into two groups according to the results of MTWA tests: non-negative group included positive and indeterminate, and negative group. Compared with the negative group, non-negative group showed increased rates of cardiac mortality or severe arrhythmic events (RR = 1.65, 95%CrI = 1.32, 2.071), sudden cardiac death (SCD) (RR = 2.04 95%CrI = 1.11, 3.75), and all-cause mortality (RR = 2.11, 95%CrI = 1.60, 2.79). The funnel plot revealed that there might be bias within current publications. The fail-safe number of composite endpoint and all-cause mortality was 14.42 and 18.93, respectively (when P = 0.01). The fail-safe number of SCD was 1.07 (when P = 0.05), which may be caused by the small case number of included studies and some patients with ICD included.

Conclusions

The non-negative group of MTWA had a nearly double risk of severe outcomes compared with the negative group. Therefore, MTWA represents a potential useful tool for judging the severity of ICM.     

微伏极T波电交替对心肌梗死急性期患者发生恶性心律失常的预测价值

目的评估微伏极T波电交替（MTWA）能否预测急性心肌梗死早期患者恶性心律失常的发生。方法起病7d内的急性ST段抬高型心肌梗死患者175例入选,根据起病12h内有无行直接经皮冠脉介入治疗（PCI）分为两亚组：Ia组（n=68行直接PCI）,Ib组（n=107未行直接PCI）。另选无心肌梗死来我院健康体检者82例作为对照组。所有入选者均做动态心电图用时域分析法检测MTWA最大值,用超声心动图检测左心室射血分数（LVEF）,用心室晚电位分析仪检测心室晚电位,观察住院期间有无恶性心律失常发生,并比较上述这些指标组间有无差异,用Logistic回归分析筛选恶性心律失常的预测因子。结果心肌梗死组合并糖尿病者高于对照组,Ib组合并糖尿病者高于Ia组。急性心肌梗死组恶性心律失常发生率、心室晚电位阳性率和MTWA最高值均高于对照组,而LVEF值低于对照组。急性心肌梗死两亚组间比较,Ib组恶性心律失常发生率、心室晚电位阳性率和MTWA最大值均高于Ia组,而LVEF值低于Ia组。Logistic回归分析结果显示MTWA最大值、LVEF、心室晚电位阳性率和有无糖尿病是患者是否发生恶性心律失常的独立预测因子,相关系数R分别为0．34、0．29、0．21、0．13,相对危险度（OR）分别为2．82、1．55、1．36、0．87,MTWA的相关性最强（R=0．34）,相对危险度最高（OR=2．82）。当LVEF和心室晚电位进入回归方程时,决定系数R^20．448,增加MTWA最大值进入回归方程后,决定系数R^2显著增加至0．628。结论MTWA最大值、LVEF和心室晚电位是早期急性心肌梗死患者恶性心律失常发生的预测因子,MTWA的预测价值优于LVEF和心室晚电位。如果三者联合运用能更好地预测早期急性心肌梗死患者恶性心律失常发生。     

Non-compaction cardiomyopathy associated with myocardial bridging: A frequently overlooked or misdiagnosed cardiomyopathy

Isolated ventricular non-compaction (IVNC) is an unclassified cardiomyopathy which occurs due to a morphogenetic abnormality involving an arrest of compaction of the loose myocardial meshwork during fetal ontogenesis. Despite recent advances in knowledge, diagnosis remains problematic because of its similarity to other diseases of the myocardium and endocardium. In this report, we describe a case of IVNC and myocardial bridging. The patient had been misdiagnosed with apical hypertrophic cardiomyopathy 2 years earlier. The correct diagnosis was established by transthoracic echocardiography and confirmed by cardiac catheterization and angiocardiography.     

Treadmill exercise test in children with cardiomyopathy and postmyocarditic myocardial hypertrophy

Summary The treadmill exercise test with the Bruce protocol was performed in three patients with postmyocarditic myocardial hypertrophy (PMH) and ten patients with cardiomyopathy, including three with dilated cardiomyopathy (DCM), five with hypertrophic obstructive cardiomyopathy (HOCM), and two with hypertrophic and nonobstructive cardiomyopathy (HCM). The endurance time was below the normal level in all but one case and was normal or near normal in the three cases with PMH. ST depression was observed in five cases, none of which were of HCM. A marked increase in amplitude of the negative phase of the P wave in V₁ was observed in one patient with DCM. The response of blood pressure during the exercise was abnormal in patients with DCM and HCM but was normal in PMH.     

Effect of bundle branch block on microvolt T-wave alternans and electrophysiologic testing in patients with ischemic cardiomyopathy

BACKGROUND: T-wave alternans (TWA) and electrophysiology study (EPS) are used for risk stratification for sudden death. OBJECTIVE: The purpose of the study was to determine the effect of bundle branch block or intraventricular conduction delay on TWA and EPS. METHODS: 386 patients with coronary artery disease, nonsustained ventricular tachycardia, and left ventricular ejection fraction < or =40% underwent TWA and EPS, and were followed for 40 +/- 19 months. RESULTS: Patients with wide QRS were more likely than narrow QRS patients to have nonnegative TWA (77% vs 63%, P <.01) or positive EPS (60% vs 48%, P = .03). Nonnegative TWA predicted the combined endpoint of ventricular tachyarrhythmia or death in narrow QRS (HR = 1.64, P = .04) but not wide QRS patients (HR = 1.04, P = .91). Similarly, positive EPS predicted the combined endpoint in narrow QRS (HR = 2.28, P <.001) but not wide QRS patients (HR = 0.94, P = .84). In multivariate analysis, QRS width and TWA, as well as QRS width and EPS, were independent predictors of events. There was no TWA- or EPS-based difference in arrhythmia-free survival within any specific wide QRS morphology. CONCLUSION: TWA and EPS are more often abnormal in patients with a wide QRS than in those with a narrow QRS. In patients with narrow QRS, both TWA and EPS stratify patients according to their risk of ventricular tachyarrhythmia or death. However, among patients with a wide QRS, regardless of specific QRS morphology, the risk is high and comparable regardless of TWA or EPS results. Therefore, the only truly low-risk group consists of those patients with negative test results and a narrow QRS.     

Asynergy and left ventricular performance in dilative cardiomyopathy

The purpose of this work was to evaluate the presence and importance of asynergy in dilative cardiomyopathy. A semiautomatized analysis of left ventriculograms was performed in 18 cases, the morphology of longitudinal and transverse axes time-length curves was evaluated, and mathematical indices of asynchrony and hypokinesis were defined. Ten normal subjects and 9 patients affected by aortic regurgitation were used as controls. In dilative cardiomyopathy, anomalous (polyphasic) time-length curves were present in 55% of the cases, while they were absent in aortic regurgitation and in all normal subjects but one. In addition, the asynchrony index was slightly increased and the hypokinesis index significantly increased (28.8 +/- 7.2% vs. 17.8 +/- 7.1%, p less than 0.001). A negative correlation existed between the asynchrony index and the ejection fraction (r = -0.483, p less than 0.05) and both the ejection fraction and the maximum normalized velocity of contraction were reduced in the patients with the anomalous curves (29.7 +/- 6.9% vs. 46.0 +/- 11.5%, p less than 0.01; 1.66 +/- 0.52 s-1 vs. 2.86 +/- 1.33 s-1, p less than 0.02). It was concluded that asynergy, and especially asynchrony, is frequent in dilative cardiomyopathy and it is strongly associated with a major impairment of overall left ventricular function.     

Left ventricular pulsus alternans in patients with hypertrophic cardiomyopathy and severe obstruction to left ventricular outflow

Left ventricular pulsus alternans (LVPA), a rhythmic beat to beat variation in left ventricular systolic pressure and outflow gradient, was noted in 35 of 200 ventricular systolic pressure and outflow gradient, was noted in 35 of 200 patients with hypertrophic cardiomyopathy undergoing hemodynamic study. LVPA was not associated with significant systemic pulsus alternans nor right ventricular pulsus alternans. All patients with LVPA had severe outflow gradients at rest or during provocation. Of 61 patients with severe basal outflow gradients (greater than 80 mm Hg), 12 demonstrated LVPA at rest. Eight of these patients underwent ventricular septal myotomy-myectomy; all had successful abolition of basal outflow gradient. Of the seven of these eight patients who underwent postoperative hemodynamic study and who were in sinus rhythm, none demonstrated LVPA. Eleven of 60 patients with basal outflow gradients ranging from 10 to 70 mm Hg demonstrated LVPA during maneuvers provocative for outflow gradients (mean gradient 90 +/- 37 mm Hg). Two of these patients underwent ventricular septal myotomy-myectomy; neither had a gradient nor LVPA during provocation postoperatively. Twelve additional patients with basal outflow gradients ranging from 0 to 115 mm Hg had LVPA after ectopic beats, generally occurring during maneuvers provocative for outflow gradients, associated with severe outflow gradients (mean gradient 130 +/- 39 mm Hg) during the postextrasystolic beat. None of the 41 patients without an outflow gradient, basal or during provocation, was found to have LVPA. Thus LVPA is commonly seen in during provocation, was found to have LVPA. Thus LVPA is commonly seen in patients with hypertrophic cardiomyopathy and severe left ventricular outflow gradients and may represent inadequate left ventricular contractile function in the presence of high left ventricular systolic pressures.