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Objectives. Risk stratification in acute congestive heart failure (ACHF) is poorly defined. The aim of the present study was to assess the impact of right bundle brunch block (RBBB) on long-term mortality in patients presenting with ACHF.
Methods and results. The initial 12-lead electrocardiogram was analysed for RBBB in 192 consecutive patients presenting with ACHF to the emergency department. The primary endpoint was all-cause mortality during 720-day follow-up. This study included an elderly cohort (mean age 74 years) of ACHF patients. RBBB was present in 27 patients (14%). Age, sex, B-type natriuretic peptide levels and initial management were similar in patients with RBBB when compared with patients without RBBB. However, patients with RBBB more often had pulmonary comorbidity. A total of 84 patients died during follow-up. Kaplan–Meier analysis revealed that mortality at 720 days was significantly higher in patients with RBBB when compared with patients without RBBB (63% vs. 39%, P = 0.004). In Cox proportional hazard analysis, RBBB was associated with a two-fold increase in mortality (hazard ratio 2.18, 95% CI 1.26–3.66; P = 0.003). This association persisted after adjustment for age and comorbidity.
Conclusions. RBBB is a powerful predictor of mortality in patients with ACHF. Early identification of this high-risk group may help to offer tailored treatment in order to improve outcome.
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The epidemic of heart failure (HF) is a major public health problem. HF is the most frequent cause of hospitalizations in patients more than 65 years of age and these hospitalizations contribute significantly to the enormous cost of the disease [1, 2]. In contrast to chronic HF, risk stratification and initial management is poorly validated in patients presenting with acute congestive heart failure (ACHF). Hence, current American College of Cardiology/American Heart Association (ACC/AHA) and European Society for Cardiology (ESC) initiatives call for more research targeting ACHF [1, 2].
The electrocardiogram (ECG) has been a cornerstone in clinical medicine for more than six decades. In contrast to current belief, additional diagnostic and prognostic applications continue to emerge each year [3, 4]. Twelve-lead ECG is an important tool in the diagnosis of ACHF, particularly in the identification of the cause of acute decompensation including tachyarrhythmia and myocardial infarction [1, 2]. It is unknown, whether electrocardiography also provides prognostic information in patients with ACHF. This would be very attractive, as electrocardiography is routinely performed, easy, safe and inexpensive. Whilst no data are available for ACHF, a large retrospective cohort study including patients with acute myocardial infarction reported that patients with right bundle brunch block (RBBB) had an increased risk of in-hospital death compared with patients with no BBB. RBBB seemed to predict in-hospital death at least as powerful as left bundle brunch block (LBBB) .
We hypothesized that RBBB may be a marker of pulmonary artery hypertension and/or right ventricular dysfunction  and may therefore be associated with increased mortality in patients with ACHF.
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This study included an elderly cohort (mean age 74 years) of ACHF patients. Nearly half of patients were women, and comorbidity including pulmonary disease was extensive (Table 1). RBBB was present in 27 patients (14%) and LBBB in 32 patients (17%). Baseline demographic, clinical, and laboratory characteristics including BNP levels and left ventricular ejection fraction (LVEF) were very similar in patients with RBBB when compared with patients without RBBB. In the BNP group, in those with RBBB no patient had a BNP < 100 pg mL−1 and 64% had a BNP > 500 pg mL−1. In those without RBBB, 5% had a BNP < 100 pg mL−1 and 66% had a BNP > 500 pg mL−1 (P = NS). Differences amongst groups were restricted to a higher incidence of pulmonary disease, tachypnea, and wheezing in patients with RBBB. In addition, concomitant left axis deviation with left anterior fascicular block was more frequent in patients with RBBB when compared with patients without RBBB (37% vs. 8%, P < 0.001). Initial management including hospitalization rate and admission to intensive care were similar amongst groups. Discharge medication was comparable in both groups with the exception of calcium channel blockers, which were prescribed more often to patients with RBBB (33% vs. 13%, P = 0.009). This difference was already present on admission.
Table 1. Patient characteristics
| ||All patients (n = 192)||RBBB (n = 27)||No RBBB (n = 165)||P value|
|Age (years)||74 ± 11||76 ± 11||74 ± 11||0.480|
|Female sex||86 (45)||9 (33)||77 (47)||0.197|
| Coronary artery disease||135 (70)||20 (74)||115 (70)||0.644|
| Arterial hypertension||125 (65)||18 (67)||107 (65)||0.854|
| COPD||43 (22)||9 (33)||34 (21)||0.141|
| Asthma||4 (2)||0||4 (2)||1.000|
| Previous pneumonia||23 (12)||6 (22)||17 (10)||0.077|
| Previous pulmonary embolism||6 (3)||2 (7)||4 (2)||0.200|
| Other pulmonary or pleural diseasea||14 (7)||5 (19)||9 (6)||0.031|
| Any pulmonary disease||77 (40)||16 (59)||61 (37)||0.028|
| Diabetes mellitus||65 (34)||12 (44)||53 (32)||0.210|
| Chronic kidney disease||75 (39)||12 (44)||63 (38)||0.536|
| Paroxysmal nocturnal dyspnoea||93 (48)||15 (56)||78 (47)||0.425|
| Nycturia||77 (40)||15 (56)||62 (38)||0.077|
| Weight gain||32 (17)||7 (26)||25 (15)||0.164|
| Systolic blood pressure (mmHg)||148 ± 32||149 ± 26||148 ± 33||0.853|
| Diastolic blood pressure (mmHg)||88 ± 22||86 ± 21||89 ± 22||0.498|
| Heart rate (per min)||98 ± 62||90 ± 17||100 ± 27||0.091|
| Temperature (°C)||37.2 ± 0.9||37.3 ± 1.0||37.2 ± 0.9||0.796|
| Tachypnoea (>20 per min)||87 (45)||17 (63)||70 (42)||0.047|
| Elevated JVP||41 (21)||6 (22)||35 (21)||0.905|
| Hepatojugular reflux||30 (16)||5 (19)||25 (15)||0.655|
| Rales||117 (61)||16 (59)||101 (61)||0.835|
| Wheezing||26 (14)||7 (26)||19 (12)||0.042|
| Hyper-resonant percussion||13 (7)||3 (11)||10 (6)||0.399|
| Lower-extremity oedema||86 (45)||11 (41)||75 (46)||0.648|
| Creatinine clearance (mL min−1/1.73 m2)||54 ± 29||51 ± 26||55 ± 29||0.545|
| Haemoglobin (g dL−1)||12.9 ± 2.4||12.4 ± 2.3||13.0 ± 2.4||0.201|
| Serum albumin (g L−1)||33 ± 6||32 ± 5||33 ± 6||0.461|
| Troponin I (μg L−1)||0.5 (0.3–2.4)||1.0 (0.3–6.3)||0.5 (0.3–2.3)||0.380|
| B-type natriuretic peptide (pg mL−1)||840 (355–1300)||847 (210–1300)||840 (372–1300)||0.545|
| Left ventricular ejection fraction (%)b||40 (30–55)||40 (22–60)||40 (30–53)||0.810|
|Medication at admission|
| ACE-inhibitor or angiotensin receptor blocker||92 (47)||16 (57)||76 (45)||0.221|
| Beta-blocker||71 (36)||9 (32)||62 (37)||0.658|
| Diuretics||125 (63)||19 (68)||106 (62)||0.576|
| Nitroglycerin||40 (20)||8 (29)||32 (19)||0.234|
| Digoxin||27 (14)||7 (25)||20 (12)||0.059|
| Calcium channel blocker||31 (16)||9 (32)||22 (13)||0.010|
| Aspirin||89 (45)||15 (54)||74 (44)||0.322|
| Anticoagulation||58 (29)||13 (46)||45 (27)||0.032|
| Oral steroids||18 (9)||7 (25)||11 (7)||0.002|
| Inhaled bronchodilators||18 (9)||5 (18)||13 (8)||0.145|
|Medication at dischargec|
| ACE-inhibitor or angiotensin receptor blocker||143 (79)||20 (83)||123 (78)||0.756|
| Beta-blocker||113 (62)||14 (58)||99 (63)||0.656|
| Diuretic||158 (87)||23 (96)||135 (86)||0.177|
| Nitroglycerin||66 (37)||8 (33)||58 (37)||0.732|
| Digoxin||19 (11)||3 (13)||16 (10)||0.722|
| Calcium channel blocker||28 (16)||8 (33)||20 (13)||0.009|
| Aspirin||89 (49)||13 (54)||76 (48)||0.599|
| Anticoagulation||90 (50)||12 (50)||78 (50)||0.977|
| Oral steroids||15 (8)||3 (13)||12 (8)||0.425|
| Inhaled bronchodilators||28 (16)||5 (21)||23 (15)||0.543|
| Hospitalization||171 (89)||26 (96)||145 (88)||0.194|
| Intensive care admission||53 (28)||8 (30)||45 (27)||0.800|
| Time to discharge (days)||11 (5–19)||14 (7–19)||10 (4–20)||0.313|
| 30-day mortality (%)||24 (13)||7 (26)||17 (10)||0.023|
| 720-day mortality (%)|| ||63.3 ± 9.4||38.6 ± 3.8||0.004|
A total of 84 patients (44%) died during follow-up. Median duration of follow-up until patient death or last contact was 686 days. No patient was lost to follow-up within the first 12 months. Kaplan–Meier analysis (Fig. 1) revealed that mortality at 720 days was significantly higher in patients with RBBB when compared with patients without RBBB (63% vs. 39%, P = 0.004). In Cox proportional hazard analysis, RBBB was associated with a two-fold increase in mortality (hazard ratio 2.18, 95% CI 1.26–3.66; P = 0.003). As shown in Table 2, this association persisted after multivariable adjustment in several models. After adjusting for age, history/comorbidity, physical examination, vital signs, laboratory tests routinely available in the ED, and discharge medication, the predictive value of RBBB was no longer statistically significant (P = 0.090). In patients with RBBB, concomitant left ventricular systolic dysfunction (LVEF < 50%) did not further impact on the risk of death (P = 0.8).
Figure 1. Survival rates in patients with right bundle branch block (RBBB) when compared with patients without RBBB.
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Table 2. Univariate and multivariate analysis of right bundle brunch block (RBBB) as a predictor of all-cause mortality
|HR (95% CI)||2.18 (1.26–3.66)|
| Multivariate P||0.012|
| HR (95% CI)||1.96 (1.16–3.31)|
| Multivariate P||0.041|
| HR (95% CI)||1.82 (1.03–3.24)|
| Multivariate P||0.090|
| HR (95% CI)||1.79 (0.91–3.51)|
In contrast to the findings regarding RBBB, mortality at 720 days was similar in patients with LBBB when compared with patients without LBBB (Fig. 2).
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In patients presenting with ACHF to the ED, the ECG offers unique diagnostic and prognostic information. The major finding of this analysis was that RBBB – but not LBBB – is a powerful predictor of long-term mortality in unselected consecutive patients. This finding has important clinical implications. First, patients with ACHF have a very high mortality rate. Despite this, there are little data regarding long-term outcome of patients with ACHF [1, 2]. Therefore, risk stratification in patients with ACHF is by far less well validated than in patients with chronic HF. Secondly, RBBB can easily be assessed from the 12-lead ECG immediately on presentation. Thirdly, rapid initiation of intensive care and several specific therapeutic interventions possibly including levosimendan  or selective PDE5 inhibition  may particularly benefit high risk patients identified by RBBB [1, 2]. Fourthly, as the presence of RBBB not only increased 30-day mortality but also long-term mortality, patients with RBBB may benefit from more intense follow-up [1, 2]. Of note, the incidence of RBBB in ACHF was twice the incidence observed in patients with moderate to severe chronic HF .
This study complements and extends previous studies on the impact of RBBB in other patient settings. Go et al.  examined patients with acute myocardial infarction and found that patients with RBBB had an increased risk of in-hospital death when compared with patients without BBB. RBBB seemed to predict in-hospital death at least as powerful as LBBB. Wong et al.  confirmed this observation by showing that RBBB accompanying anterior acute myocardial infarction is an independent predictor of 30-day mortality [12, 13]. Similar findings were reported in patients referred for symptom-limited nuclear exercise testing. Complete RBBB and LBBB were independent predictors of all-cause mortality risk even after adjustment for exercise capacity, nuclear perfusion defects, and other risk factors . Together with these reports, our data strongly contradict the dogma that RBBB heralds a much more favourable cardiovascular prognosis than LBBB . Instead, our data highlight the fact that the prognostic impact of RBBB depends on the clinical setting in which it is recorded.
Why does RBBB predict mortality in ACHF?
By its observational design, our study can only partly elucidate the links between RBBB and mortality. RBBB may result from various disorders affecting the right heart including pulmonary comorbidity. RBBB indicates structural changes in the right ventricle and may highlight that pulmonary hypertension and/or right ventricular dysfunction has complicated the clinical course of the primarily left heart disease resulting in ACHF. In this regard, ACHF seems to have some pathophysiological details in common with acute anterior myocardial infarction [11, 13]. Both are disorders primarily involving the left ventricle where secondary pulmonary hypertension due to severe left ventricular dysfunction or confounding right ventricular disease may impact on outcome. Supporting this concept and data from Wong et al. , a large cohort study demonstrated that RBBB increased in-hospital and 1-year mortality rates in patients with acute anterior myocardial infarction . Moreover, recent studies have shown that right ventricular systolic function as quantified by either echocardiography or right heart catheterization is an independent predictor of death in patients with chronic HF [4, 16–18]. In ACHF, RBBB may result from right ventricular pressure overload induced by the combination of passive transduction of increased left atrial pressure and hypoxia-triggered increase in pulmonary vascular resistance [1, 2]. Therefore, selective PDE5 inhibition might be a potential therapeutic strategy in ACHF patients with RBBB . Obviously, further clinical studies are necessary to test this hypothesis. Concomitant left axis deviation with left anterior fascicular block was more frequent in patients with RBBB when compared with patients without RBBB. This finding is supported by previous studies and suggests the concept of ventricular dyssynchrony as reason for worse outcome [19–21]. Moreover, detailed investigations of the impact of RBBB on ventricular interdependence seem warranted .
How to detect right ventricular dysfunction in ACHF
Obviously, echocardiography and right heart catheterization provide more detailed information regarding right ventricular dysfunction than the ECG. However, logistic and practical considerations limit the use of echocardiography and right heart catheterization in patients presenting with ACHF to the ED. Respiratory distress, tachypnoea, inability to maintain the supine position are major limitations on the patient side. In addition, echocardiography and right heart catheterization require expertise and devices often not available on a 24-h basis in the ED. In contrast, the ECG is simple, inexpensive, readily available in an ED, and can be interpreted with high accuracy by emergency or internal medicine specialists working in the ED.
Why does LBBB not predict mortality in ACHF?
Left bundle brunch block indicates structural changes in the left ventricle and has consistently been shown to be a powerful predictor of cardiovascular disease and mortality in the general population [11, 12, 23]. In patients with acute myocardial infarction, LBBB identifies a high-risk group with increased comorbidity, less likely to receive therapy, and increased risk for in-hospital death . Moreover, LBBB seems to be a predictor of mortality in stable outpatients with chronic HF . Therefore, at first glance it is surprising that LBBB does not predict mortality in ACHF. The following consideration may explain this observation. By definition, the vast majority of patients with ACHF do have advanced cardiac disease involving the left ventricle that is severe enough to cause ACHF. Therefore, LBBB as an indicator of left ventricular disease does not provide additional prognostic information in a cohort of patients with severe left ventricular disease resulting in ACHF.
Our analysis has three particular strengths. First, it included a large contemporary cohort of consecutive patients. Secondly, the study population was highly representative of the elderly population of patients with ACHF in clinical practice [1, 2]. Thirdly, it is one of the first studies of patients with ACHF providing long-term follow-up data [2, 9].
Potential limitations of the present study merit consideration. First, this was a post-hoc analysis of a randomized controlled trial. However, as the BASEL study recruited consecutive patients, we are not aware of any bias potentially confounding our results. Secondly, echocardiography was performed during hospitalization in two-thirds of patients. However as common in clinical routine, this assessment did not include standardized measurement of right ventricular ejection fraction. Additional studies seem warranted to evaluate whether measurement of right ventricular ejection fraction provides additional prognostic information to that obtained by the simple identification of RBBB in the ECG of patients with ACHF. Thirdly, the onset of RBBB as well as potential disappearance during follow-up was unknown in our cohort. Systematic ECG follow-up might reveal whether patients have improved outcome once RBBB disappears.