Prognostic differences between different types of bundle branch block during the early phase of acute myocardial infarction: insights from the Hirulog and Early Reperfusion or Occlusion (HERO)-2 trial

AIMS

Bundle branch block (BBB) early during acute myocardial infarction (AMI) is often considered high risk for mortality. Little is known about how different BBB types influence prognosis.

METHODS AND RESULTS

The HERO-2 trial recruited 17 073 patients with ischaemic symptoms lasting >30 min and either ST elevation with or without right bundle branch block (RBBB) or presumed-new left bundle branch block (LBBB). Electrocardiograms were performed before and 60 min after the start of fibrinolytic therapy. Using patients with normal intraventricular conduction as a reference, odds ratios (ORs) for 30-day mortality were calculated for different BBB types (LBBB, RBBB with anterior AMI, and RBBB with inferior AMI) present at randomization and/or 60 min, with adjustment for recruitment region, pre-infarction characteristics, time to randomization, hemodynamics, and Killip class. At randomization, the 873 patients (5.11%) with BBB had worse baseline characteristics than patients without BBB. In patients presenting with LBBB (n=300), the ORs for 30-day mortality were 1.90 (95% CI 1.39-2.59) before and 0.68 (0.48-0.99) after adjustment for other prognosticators. In patients presenting with RBBB (n=415) and anterior AMI, the ORs were 3.52 (2.82-4.38) before and 2.48 (1.93-3.19) after adjustment. In patients presenting with RBBB and inferior AMI (n=158), the ORs were 1.74 (1.06-2.86) before and 1.22 (0.71-2.08) after adjustment. Within 60 min, 143 patients (0.92%) developed new BBB. The adjusted ORs for 30-day mortality were 2.97 (1.16-7.57) in the 25 patients with new LBBB, 3.84 (2.38-6.22) in the 100 with new RBBB and anterior AMI, and 2.23 (0.54-9.21) in the 18 with new RBBB and inferior AMI.

CONCLUSION

RBBB accompanying anterior AMI at presentation and new BBB (including LBBB) early after fibrinolytic therapy are independent predictors of high 30-day mortality. These electrocardiographic features should be considered in risk stratification to identify high-risk patients.

Bundle-branch block in middle-aged men: risk of complications and death over 28 years

AIMS

To investigate the long-term fate of men with bundle-branch block (BBB) from a general population sample.

METHODS AND RESULTS

Data were derived from 7392 men without a history of myocardial infarction or stroke, born between 1915 and 1925 and investigated between 1970 and 1973. All participants were followed from the date of their baseline examination until 1998. We identified 70 men with right-BBB and 46 men with left-BBB at baseline. In men with right-BBB, there was no increased risk of myocardial infarction, coronary death, heart failure, or all-cause mortality during follow-up. The multiple-adjusted hazard ratio for progression to high-degree atrioventricular block was 3.64 (99% confidence interval 0.79-16.72). In men with left-BBB, the hazard ratio for high-degree atrioventricular block was 12.89 (4.13-40.24). However, hazard ratio for all-cause mortality was 1.85 (1.15-2.97) when compared with men without BBB, mostly due to outside hospital coronary deaths, whose hazard ratio was 4.22 (1.90-9.34).

CONCLUSION

The presence of BBB was strongly associated with future high-degree atrioventricular block that was more pronounced for left-BBB. Men with left-BBB have a substantially increased risk of coronary death, mainly due to sudden death outside the hospital setting.

Cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) addresses abnormal left ventricular (LV) activation that produces detrimental effects on cardiac systolic and diastolic function. CRT improves symptoms and ventricular performance, promotes reverse remodeling, and decreases mortality and hospitalization in patients with congestive heart failure (CHF). Atrial-synchronized biventricular stimulation reverses many of the temporal delays in mechanical activation associated with LV dysfunction and conduction system disease. The therapy evolved from anecdotal application through surgical implantation of LV pacing leads to transvenous delivery of LV pacing leads for use with dedicated CRT devices. The controlled clinical trials included specific patient groups, and provided data leading to widely adopted indications for the therapy. Current indications exclude the use of CRT in patients with permanent atrial fibrillation, although small series suggest a benefit of the therapy in these patients. The role of cardiac imaging with echocardiography to detect cardiac dyssynchrony promises to improve patient selection by not only excluding likely nonresponders, but also extending the therapy to those with dyssynchrony in the absence of QRS prolongation. Expanded indications under evaluation include the role of CRT in patients with mildly symptomatic CHF, mild to moderate LV dysfunction, dyssynchrony in the absence of QRS prolongation, and dyssynchrony induced by right ventricular pacing.

Comparison of the prognostic effect of left versus right versus no bundle branch block on presenting electrocardiogram in acute myocardial infarction patients treated with primary angioplasty in the primary angioplasty in myocardial infarction trials

The presence of bundle branch block (BBB) has been associated with poor outcomes in patients who have acute myocardial infarction. Whether this is true in the angioplasty era is not known. We sought to evaluate the outcome of patients with acute myocardial infarction and BBB who were treated with primary angioplasty. We evaluated 3,053 patients who underwent emergency catheterization in the PAMI trials. Patients who had left BBB (n = 48, 1.6%) on presenting electrocardiogram were compared with patients who had right BBB (n = 95, 3.1%) or no BBB (n = 2,910, 95.3%). Patients who had BBB were older and more frequently had diabetes mellitus, peripheral vascular disease, and previous coronary artery bypass grafting. They had lower ejection fraction and more multivessel disease. There were no significant differences in door-to-balloon time, final Thrombolysis In Myocardial Infarction flow grade or stent use. In-hospital major adverse cardiac events (death, ischemic target vessel revascularization, and reinfarction) were higher in patients who had BBB due primarily to increased in-hospital death (left BBB 14.6%, right BBB 7.4%, no BBB 2.8%, p < 0.0001). In multivariate logistic regression analysis, left BBB was an independent predictor of in-hospital death (odds ratio 5.53, 95% confidence interval 1.89 to 16.1, p = 0.002). In conclusion, patients who have acute myocardial infarction and BBB have increased co-morbidities and higher mortality rates despite treatment with primary angioplasty. Despite early identification of multivessel disease with triage to angioplasty or coronary artery bypass grafting, if necessary, similar treatment times, and final Thrombolysis In Myocardial Infarction grade 3 flow, the presence of left BBB on admission electrocardiogram in patients who have acute myocardial infarction is an independent predictor of in-hospital mortality. Because 85% of deaths in patients who have left BBB occur within the first week, these patients should be recognized early and receive prompt and aggressive treatment.

Bundle branch block patterns, age, renal dysfunction, and heart failure mortality

BACKGROUND

The determinants of bundle block patterns and their relationship to mortality in heart failure patients is not completely understood.

METHODS

We evaluated 2907 consecutive patients admitted to an intensive care unit with decompensated heart failure over 8 years. Clinical and echocardiographic factors were analyzed using multivariate techniques. All-cause mortality was available on greater than 99.0% of patients at a median of 23 months after discharge.

RESULTS

Right and left bundle branch blocks occurred in 211 (7.3%) and 386 (13.2%), p<0.0001. Older age, decreased left ventricular ejection fraction, and renal dysfunction were all found to be independently associated with bundle branch block patterns. Mortality rates for the subgroups of QRS<120 ms, right bundle branch block and left bundle branch block, over a mean follow-up of 23.4+/-2.6 months were 46.1%, 56.8% and 57.7%, p<0.0001 for comparison of QRS<120 ms versus either bundle pattern. Cox proportional hazards model adjusting for age, sex, ejection fraction, and renal function demonstrated graded decrements in survival in those with QRS<120 ms, right bundle branch block and left bundle branch block, p=0.03.

CONCLUSIONS

In patients hospitalized with severe heart failure, age, left ventricular dysfunction, and renal dysfunction are associated with bundle branch block patterns. When controlling for these factors, bundle branch block patterns are independently associated with slightly higher all cause mortality after discharge.

Prognostic implication of activated partial thromboplastin time after reteplase or half-dose reteplase plus abciximab: results from the GUSTO-V trial

AIMS

To evaluate the relationship between activated partial thromboplastin time (aPTT) and clinical outcomes in the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO-V) trial comparing standard-dose reteplase to half-dose reteplase and abciximab.

METHODS AND RESULTS

We analysed data on 11,420 patients receiving unfractionated heparin. Peak aPTT levels recorded during the hospitalization were correlated with clinical outcomes. Multivariable logistic regression models examined the relationship between peak aPTT levels and (i) moderate-to-severe bleeding, (ii) intracerebral haemorrhage, (iii) reinfarction, and (iv) 30-day mortality. Non-linear relationships were explored in the models using cubic spline functions. Higher rates of significant complications were seen in both groups when aPTT levels were <50 s or when levels were >70 s. In the combination therapy group, the relationship between aPTT levels and bleeding appeared accentuated. Reinfarction rates increased gradually as aPTT levels were >70 s in both groups, but the relationships were not statistically significant. Peak aPTT levels <50 s were associated with increased 30-day mortality even after multivariable adjustment.

CONCLUSION

Peak aPTT levels <50 s and >70 s are associated with worse clinical outcomes in the modern era of fibrinolytic therapy; these relationships are different in patients receiving standard reteplase vs. combination therapy.

Surgical epicardial left ventricular lead versus coronary sinus lead placement in biventricular pacing☆

OBJECTIVE

Biventricular pacing has demonstrated improvement in cardiac function in treating congestive heart failure (CHF). Two different operative strategies (coronary sinus vs. epicardial stimulation) for left ventricular (LV) pacing were compared.

METHODS

Since April 1999, a total of 86 patients (pts, age: 63+/-10 years) with depressed systolic LV function (mean ejection fraction 24+/-9%), left bundle-branch-block (mean QRS 182+/-22 ms) and congestive heart failure NYHA III or higher were enrolled. For biventricular stimulation coronary sinus (CS) leads were placed in 79 pts. Nine of these devices were converted to surgical epicardial LV-leads, because of CS-lead failure. In 7 patients epicardial LV-leads were initially implanted surgically, accounting for a total of 16 pts with surgical placed epicardial steroid-eluting LV-leads. For these, a limited left-lateral thoracotomy (7+/-4 cm) was used. Thirty-three (38%) pts had an indication for a defibrillator. The mean follow-up time was 16.4+/-15.4 months (0.1-45 months), representing 107.1 patient-years.

RESULTS

In the biventricular pacing mode, QRS duration decreased to 143+/-16 ms (P<0.001). Threshold capture of the CS-leads increased significantly compared to surgically placed epicardial leads (18 month control: 2.2+/-1.4V/0.5 ms vs. 0.7+/-0.3V/0.5 ms), which had no increase in threshold (P<0.001). At the 18 month follow-up 7 CS-leads had a threshold of >4V/0.5 ms vs. epicardial leads which were under 1.1V/0.5 ms, except for one (1.8V/0.5 ms). After CS-lead implantation 25 LV-lead related complications occurred, (failed implantation, CS-dissection, loss of pacing capture, diaphragm stimulation or lead dislodgment), vs. one dislodgement after surgical epicardial lead placement (P<0.05). Correct lead positioning (obtuse marginal branch area) was achieved in all surgical epicardial placements but only in 70% with CS-leads (P<0.03). In the follow up period, 9 pts died (4 cardiac related). Heart transplantation was necessary in 4 pts due to deterioration of the cardiomyopathy.

CONCLUSIONS

Surgical epicardial lead placement revealed excellent long-term results and a lower LV-related complication rate compared to CS-leads. Although, the approach via limited thoracotomy for biventricular pacing is associated with 'more surgery', it is a safe and reliable technique and should be considered as an equal alternative.

The interaction among sex, hemoglobin and outcomes in a specialty heart failure clinic

PURPOSE

Although anemia has recently been demonstrated to be a marker for poor outcomes in patients with congestive heart failure (CHF), the impact of sex on the prevalence and prognostic impact of anemia has not been adequately explored. Accordingly, the relationship among sex, anemia and outcomes in CHF was analyzed.

SUBJECTS

Patients seen at a specialty CHF clinic from 1989 to 2001.

METHODS

A retrospective analysis of prospectively collected data was performed using chi2 and Student's t tests to determine the association between anemia and mortality. Multivariate Cox proportional hazards models were used to measure the independent association of anemia with mortality in men and women. The World Health Organization definition of anemia (less than 130 g/L for men; less than 120 g/L for women) and the Centers for Disease Control and Prevention definition of anemia (less than 135 g/L for men, less than 120 g/L for women) were used, and hemoglobin was assessed as a continuous variable.

RESULTS

There were 791 patients with CHF seen over a 12-year period (median age 69 years, median hemoglobin of 131 g/L [interquartile range 119 to 144 g/L]) and 34% were women. The demographics and treatments were similar for men and women, except that women were older (69 years versus 65 years, P<0.001), more likely to have a nonischemic etiology of CHF (P<0.001) or diastolic dysfunction (P<0.001), and lower creatinine clearances (P<0.001). Forty per cent of men and 35% of women were anemic using the World Health Organization definition. Anemia was associated with a one-year and five-year excess mortality in men (adjusted OR 1.7 [1.1 to 2.5] and 1.76 [1.2 to 2.7], respectively), but this was not observed in women (adjusted OR 1.2 [0.7 to 2.2] and 1.2 [0.7 to 2.1], respectively).

CONCLUSIONS

Anemia is prevalent in heart failure and predicts mortality in men but not in women. Given this result, the authors recommend that randomized trials evaluating novel therapies for the correction of anemia in patients with heart failure should stratify their randomization by sex.

Assessment of Markers for Identifying Patients at Risk for Life-Threatening Arrhythmic Events in Brugada Syndrome

INTRODUCTION

Risk stratification for life-threatening arrhythmic events in Brugada syndrome is not yet established. The aim of the present study was to examine the usefulness of various markers in predicting life-threatening arrhythmic events in the Brugada syndrome.

METHODS AND RESULTS

Forty-six patients with Brugada-type ECGs were categorized into the symptomatic (n=28) and asymptomatic (n=18) groups. Statistical analyses were performed with respect to the usefulness of the following markers: SCN5A mutation, pharmacologic challenge, ventricular fibrillation (VF) inducibility by programmed electrical stimulation, and late potential (LP) by signal-averaged ECG (SAECG). Comparison between the two groups revealed a significant difference only in LP positivity (92.6% vs 47.1%, P=0.0004). The symptomatic group had significantly lower RMS40, longer LAS40, and longer fQRSd compared with the asymptomatic group. A significant difference was noted, especially RMS40. The positive predictive value, negative predictive value, and predictive accuracy when setting a cutoff value of 15 microV were 92.0%, 78.9%, and 86.4%, respectively. Furthermore, patients with an RMS40 value <15 microV (n=25) showed significantly higher rates of VF recurrence compared with patients with an RMS40 value > or = 15 microV (n=19, P=0.047).

CONCLUSION

Regarding risk stratification for identifying high-risk patients in Brugada syndrome, only LP by SAECG was shown to be useful, suggesting the importance of RMS40 in predicting the history of life-threatening arrhythmic events and the recurrence of VF.

Mortality rates in patients with ST-elevation vs. non-ST-elevation acute myocardial infarction: observations from an unselected cohort

AIMS

Acute myocardial infarction (AMI) is categorized, according to the presenting electrocardiogram, into non-ST-elevation myocardial infarction (non-STEMI), ST-elevation myocardial infarction (STEMI), or bundle branch block myocardial infarction (BBBMI). Data on the prognostic significance of these categories mainly originate from voluntary based registries or large-scale clinical trials and may be hampered by selection and information bias. The aim of this historical cohort study was to evaluate the prognostic significance of different categories of AMI in an unselected cohort.

METHODS AND RESULTS

From 1 November 1999 to 31 October 2001, patient records were reviewed from all admissions to hospitals serving a study region with 139,000 inhabitants. An Endpoint Committee determined whether patients fulfilled the European Society of Cardiology criteria of AMI. A total of 654 patients with AMI were identified. The proportion having non-STEMI, STEMI, and BBBMI was 54, 39 and 6%, and the associated 1 year mortality was 31, 21, and 55%, respectively (log rank 54, P<0.001). The more favourable outcome observed in patients with STEMI remained significant according to multivariable analysis (P=0.044).

CONCLUSION

In an unselected cohort of patients admitted with AMI, the mortality was considerably higher than expected from voluntary-based registries and large-scale clinical trials. The most favourable outcome is observed in patients with STEMI.

Comorbidity and Myocardial Dysfunction Are the Main Explanations for the Higher 1-Year Mortality in Acute Myocardial Infarction With Left Bundle-Branch Block

BACKGROUND

The purpose of this study was to assess the independent contribution of left bundle-branch block (LBBB) on cause-specific 1-year mortality in a large cohort with acute myocardial infarction (MI).

METHODS AND RESULTS

We studied a prospective cohort of 88,026 cases of MI from the Register of Information and Knowledge about Swedish Heart Intensive care Admissions in 72 hospitals in 1995 to 2001. Long-term mortality was calculated by Cox regression analysis, adjusted for multiple covariates that affect mortality by calculation of a propensity score. LBBB was present in 9% (8041 of 88,026) of the MI admissions. Patients with LBBB were older and had a higher prevalence of comorbid conditions than patients with no LBBB. The unadjusted relative risk of death within 1 year was 2.16 (95% CI, 2.08 to 2.24; P<0.001) for LBBB (42%, 3350 of 8041) compared with those with no LBBB (22%, 17,044 of 79,011). After adjustment for a propensity score that takes into account differences in risk factors and acute intervention, LBBB was associated with a relative risk of death of 1.19 (95% CI, 1.14 to 1.24; P<0.001). In a subgroup of 11,812 patients for whom left ventricular ejection fraction was available and could be added to the analysis, the contributing relative risk of LBBB for death was only 1.08 (95% CI, 0.93 to 1.25; P=0.33). The most common cause of death in both groups was ischemic heart disease.

CONCLUSIONS

MI patients with LBBB have more comorbid conditions and an increased unadjusted 1-year mortality. When adjusted for age, baseline characteristics, concomitant diseases, and left ventricular ejection fraction, LBBB does not appear to be an important independent predictor of 1-year mortality in MI.

Cardiac resynchronization therapy in congestive heart failure: Ready for prime time?

OBJECTIVES/BACKGROUND

The aim of this article is to critically review the data accumulated to date on the application of cardiac resynchronization therapy (CRT) via biventricular pacing techniques to manage patients with advanced heart failure. The data from studies evaluating the effects of long-term right ventricular (RV) pacing are also briefly reviewed.

METHODS

MEDLINE and selective journal searches of English-language reports and a search of references of relevant papers were conducted.

RESULTS

Cardiac dyssynchrony as reflected by a prolonged QRS complex, often in the form of left bundle branch block, is encountered in about 30% of patients with moderate-to-advanced heart failure. Among these patients, 10% to 15% are candidates for CRT via biventricular pacing. Accumulated evidence from randomized controlled studies over the last few years has indicated a significant hemodynamic and clinical improvement conferred by CRT to class III or IV heart failure patients with idiopathic or ischemic dilated cardiomyopathy having a low left ventricular ejection fraction (</=35%) and a wide QRS complex (>/=120-150 ms). Newer data suggest a significant reduction in overall mortality and heart failure hospitalization, particularly when CRT is combined with automatic defibrillator backup. Technical advances with percutaneous methods accessing the tributaries of the cardiac veins have raised the success rate of implantation of left ventricular leads to >90%. Further confirmation from ongoing trials is awaited, and more data from cost-effectiveness studies are needed before CRT is considered for prime time therapy in the heart failure population. If the data confirm a survival benefit from CRT, use of this electrical therapy at earlier stages of heart failure might be contemplated. New evidence from recent studies suggests a deleterious effect of the long-standing practice of producing an iatrogenic left bundle branch block by conventional RV apical pacing in patients receiving permanent pacemakers. Thus, having already become poignantly aware of the harmful effects of spontaneous left bundle branch block, this emerging new evidence about RV apical pacing would dictate a change of attitude and direct our attention to alternate sites of pacing, such as the left ventricle and/or the RV outflow tract, if not for all patients then at least for those with left ventricular dysfunction.

CONCLUSIONS

CRT offers hemodynamic and clinical improvement to patients with moderate-to-advanced heart failure, and it might significantly prolong survival in selected patients, particularly if devices with defibrillation backup are used. Further confirmatory data from randomized mortality trials are needed, and issues of cost efficacy must be resolved before this vital therapeutic alternative is ready for prime time therapy of heart failure patients.

Clinical Characteristics of Subjects with the Brugada-Type Electrocardiogram:. A Case Control Study

INTRODUCTION

The Brugada-type ECG, a terminal r' wave accompanied by ST segment elevation in the right precordial leads, is not a very rare condition. Most of the cases are men in Japan and elsewhere; however, information about the clinical features of these cases is lacking. The aim of this study was to determine the clinical characteristics of subjects with the Brugada-type ECG, specifically Japanese men.

METHODS AND RESULTS

We extracted male Brugada-type ECG cases from 3,374 men followed biennially from 1958 through 2001 in Nagasaki, Japan, and compared the clinical characteristics at diagnosis between these cases and four age-matched male controls for each case. A total of 34 cases with the Brugada-type ECG were observed during follow-up. Body mass index (BMI) at diagnosis was significantly lower in Brugada-type ECG cases than in 136 controls (20.2 +/- 2.1 kg/m(2) vs 21.8 +/- 2.8 kg/m(2), P = 0.003). The BMI trend in cases was always lower than that in controls throughout the 8-year observation period (from 4 years before diagnosis to 4 years after diagnosis). Pulse rate at diagnosis was also somewhat lower in Brugada-type ECG cases than in controls (68.9 +/- 7.7 beats/min vs 72.7 +/- 11.1 beats/min, P = 0.038). The significance disappeared after controlling for BMI (P = 0.131) or body weight (P = 0.153).

CONCLUSION

The cases with the Brugada-type ECG had lower BMI than controls, leading to a clue to possible basic mechanisms of the Brugada-type ECG with a focus on this association.

Prevalence and prognosis of subjects with Brugada-type ECG pattern in a young and middle-aged Finnish population

AIMS

The purpose of this study was (1) to determine the prevalence of Brugada syndrome ECG abnormalities ("Brugada sign") in two Finnish populations and (2) to evaluate the natural course of subjects with the "Brugada sign".

METHODS AND RESULTS

The study population consisted of 2479 healthy male Air Force applicants (age 18-30 years), and 542 healthy middle-aged subjects (age 40-60 years). All subjects underwent a thorough physical examination and 12-lead ECG in 1980-1990 (first population) and in 1991-1992 (second population). The ECG criteria suggested by the European Society of Cardiology were used to identify subjects with the "Brugada sign". Fifteen (0.61%) subjects in the first population and three subjects in the second population (0.55%) fulfilled the ECG criteria for type 2 or 3 Brugada syndrome, i.e., they had J-point elevation and a saddleback-type ST-segment configuration in the right precordial leads. Type 1 Brugada ECG abnormality (coved ST-segment elevation) was not seen in any subject. No mortality or life-threatening ventricular arrhythmias occurred in either study population during follow-up (19+/-2 years and 11+/-1 years, respectively).

CONCLUSION

The benign natural course of the patients with the "Brugada sign" suggests that in asymptomatic subjects without a family history of sudden cardiac death, type 2 or 3 Brugada ECG pattern is a normal variant rather than a specific predictor of life-threatening ventricular arrhythmias.

Brugada syndrome--an under-recognized electrical disease in patients with sudden cardiac death

In 1992, Brugada and Brugada described 8 patients with a history of aborted sudden death and a distinct ECG pattern of right bundle-branch block with ST segment elevation in leads V1-V3 and normal QT interval in the absence of any structural heart disease. It is called Brugada syndrome now and is believed to be responsible for 4-12% of all sudden deaths and around 20% of deaths in patients with structurally normal hearts. Although this syndrome is observed worldwide and the exact prevalence is unknown, it is more common in the Southeast Asian countries. Repeated syncope, ventricular fibrillation, and sudden cardiac death have been reported in patients with Brugada syndrome. The clinical presentation of Brugada syndrome is distinguished by a male predominance and the appearance of arrhythmic events at an average age of 40 years. The Brugada syndrome is inherited in an autosomal dominant manner with incomplete penetrance and an incidence ranging between 5 and 66 per 10,000. The surface ECG manifestations of the syndrome can transiently disappear, but can be unmasked by potent sodium channel blockers in some cases. Mutations of the cardiac sodium channel SCN5A have been detectable in <20% of patients with Brugada syndrome. Recent genetic studies have confirmed the genetic heterogeneity of the disorder. Antiarrhythmic drugs appear to be of little use in prolonging survival and in preventing recurrences of ventricular arrhythmias. To date, implantable cardioverter defibrillator remains the best therapy to prevent sudden death in these patients.

Cardiac resynchronisation may reduce all-cause mortality: meta-analysis of preliminary COMPANION data with CONTAK-CD, InSync ICD, MIRACLE and MUSTIC

Landmark trials have demonstrated that biventricular pacing (also called cardiac resynchronisation therapy or CRT) in chronic heart failure due to left ventricular dysfunction improves symptomatic status, exercise capacity and quality of life. Yet critically, all-cause mortality has not been demonstrated to be reduced in any of the four randomised controlled trials with mortality data (CONTAK-CD, InSync implantable-cardioverter defibrillator (ICD), MIRACLE and MUSTIC). With the much larger COMPANION study now terminated, however, the currently available pooled data from all five trials shows a significant reduction in all-cause mortality, odds ratio (OR), 0.74: 95% confidence interval (CI) 0.56-0.97. This may now establish biventricular pacing as a standard therapy for a specific subset of patients with chronic heart failure and LBBB.

Prediction of mortality in patients with right bundle branch block referred for pharmacologic stress echocardiography

Right bundle branch block (RBBB) is independently associated with all-cause mortality in patients referred for noninvasive evaluation of coronary artery disease. However, further stratification of risk in these patients has not been specifically addressed. The aim of this study was to risk stratify patients with RBBB who were referred for stress echocardiography. The study population was comprised of 343 patients (267 men; age 66 +/- 9 years) with RBBB who underwent pharmacologic stress echocardiography (231 dipyridamole, 112 dobutamine) for evaluation of suspected or known coronary artery disease. Overall mortality was the only end point. Stress echocardiography was positive for ischemia in 109 patients (32%). During follow-up (38 +/- 32 months), 36 deaths occurred. Seventy-three patients underwent revascularization and were censored. Ischemia at stress echocardiography (hazard ratio [HR] 2.9, 95% confidence interval [CI] 1.5 to 5.5, p=0.002), left anterior fascicular block (LAFB) (HR 2.8, 95% CI 1.4 to 5.6, p = 0.002), age >65 years (HR 2.1, 95% CI 1.0 to 4.3, p=0.047), and wall motion score index at rest (HR 2.5, 95% CI 1.0 to 6.5, p=0.057) were multivariate predictors of mortality. On the basis of stress echocardiographic result and presence and/or absence of LAFB, 3 levels of risk were identified: (1) low-risk, in cases of no ischemia and no LAFB (49% of the entire study population); (2) intermediate-risk, in cases of ischemia or LAFB only; and (3) high-risk, in cases of ischemia and LAFB. Clinical data, electrocardiography at rest, and stress echocardiographic results can provide effective stratification of risk in patients with RBBB.

ECG abnormalities in the elderly: prevalence, time and generation trends and association with mortality

BACKGROUND AND AIMS

Electrocardiographic (ECG) abnormalities are often found in older patients but relatively few epidemiological studies have been performed. This study describes: a) cross-sectional differences in ECG abnormalities among three 70-year-old cohorts born over a period of 30 years; b) longitudinal changes in ECG abnormalities from the age of 70 to 85; and c) the relationship between ECG abnormalities at age 70 and subsequent 10- and 15-year mortality in men and women.

METHODS

Trends in the prevalence of ECG abnormalities were investigated among 2100 70-year olds (994 men, 1106 women) from three cohorts born in 1901/02 (I), 1911/12 (III) and 1930 (VI). Longitudinal changes and mortality risks were investigated among 973 70-year olds (449 men and 524 women) from cohort I, which was followed from 1971 until 2001.

RESULTS

In both sexes, the prevalence of ECG abnormalities was significantly lower in the later-born cohorts. From age 70 to 85, there was an increase in both men and women of large or intermediate Q-waves, left axis deviation, negative T-waves (0-5 mm), complete right bundle branch block (RBBB), and atrial fibrillation or flutter. Compared with those with no ECG abnormalities, the mortality risk was higher among individuals with large and intermediate Q-waves and negative T-waves (> or = 1 mm) in both sexes, and STJ depression > or = 0.5 mm and complete LBBB together with complete RBBB and intraventricular block; QRS > or = 0.12 sec in men only.

CONCLUSIONS

ECG abnormalities are frequent in the elderly, they increase with age, and are associated with increased mortality.

Window to the heart: the value of a native and paced QRS duration. Current perspective and review

Given the technological advances and reliance upon expensive testing for guiding therapy, it is surprising how an inexpensive, low tech electrocardiogram can provide a wealth of information pertaining to the underlying cardiovascular status of a patient. In this article we review the changes in hemodynamics, prognosis and guidance of therapeutic options associated with a prolonged QRS duration.

[The importance of left bundle branch block in the diagnosis of acute myocardial infarction]

Electrocardiographic (ECG) evidence of cardiac ischemia or infarction is difficult to detect in the presence of left bundle branch block (LBBB). Traditional ECG indicators of ischemia, such as ST- segment elevation, are common in LBBB and may not indicate acute ischemia. Proper evaluation of the initial ECG is crucial in selecting candidates for early thrombolysis, because the earlier reperfusion treatment is administred, the better are the results. Individuals with LBBB are particularly important stratum of patients to identify. This is true not only because they have a high baseline mortality and receive the greatest incremental improvement in survival when given thrombolytic agents but also because it is tendency to undertreat them. The criteria of Sgarbosa are too insensitive to be used as screening (roule out) test to determine which patients with an LBBB do not have an AMI. The Sgarbosa criteria are, however, highly specific and can be used reliably as confirmatory test to rule in AMI in patients with LBBB. ECG alone doesn't support the diagnosis of AMI. Elevated value of biochemical markers of myocardial necrosis in the presence of LBBB confirms the diagnosis. Despite the recently updated joint practical guidelines of American Heart Association (AHA) and American College of Cardiology (ACC) which defines that all patients having symptoms consistent with acute MI and LBBB should be treated like ST-segment elevation, only minority of them receive thrombolytic therapy, particularly the elderly (only 4%). In the absence of definitive diagnosis of AMI doctors withhold from decision to administer thrombolytic treatment because of risk of haemorrhagic complications. There are not perfect diagnostic tools allowing early diagnostic of AMI in patients having LBBB. Currently the best justified strategy is to follow AHA/ACC recommended guidelines to administer thrombolysis to all patients with LBBB presenting with chest pain, particularly if serum biomarkers are elevated.

T-Wave Alternans in Patients with Right Ventricular Tachycardia

Microvolt T-wave alternans has been proposed as a new risk marker for ventricular arrhythmias. However, the clinical significance of T-wave alternans in patients with ventricular tachycardia (VT) originating from the right ventricle has been unknown. The study population consisted of 20 patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) or idiopathic VT. T-wave alternans was measured during bicycle exercise testing using the CH 2000 system. Of the 7 patients with ARVC, 6 (86%) were positive for T-wave alternans. On the other hand, only 1 (8%) of 13 patients with idiopathic VT originating from the right-ventricular outflow tract was positive for T-wave alternans.