Thursday, March 31, 2005
Why do I care about this? Guess who has LBBB - and in fact, said LBBB was noticed almost 10 years ago, when I was getting my gall bladder removed, and had an EKG. At the time, the doctors thought nothing much of it except that I should remember to mention it before any future EKGs or surgery; in and of itself, LBBB is not supposed to be dangerous. (Sort of like those prolapsed mitral valves aren't supposed to be too bad if that's all that's wrong...) And then, the partial fix for this is the 3-lead pacemaker... that would be the one they couldn't do on me, I have the pacemaker but they couldn't implant the third lead, something weird about the veins back there. Bleah.
Oh well. I've still got other factors in my favor, including having lost lots of weight.
Most of these articles are pretty technical; if you follow the links, be prepared for some very medical-research-y wordiness.
http://www.eurheartj.org/cgi/content/full/25/1/97
Mortality in congestive heart failure complicated by atrial fibrillation
... It is interesting that the proportion of patients with ischaemic heart disease (IHD) was found to be higher (53.3%) in group A (no LBBB or AF) than in the groups of patients with LBBB, AF or both (33.3–35.4%). This suggests that LBBB and AF are more commonly found in association with non-ischaemic cardiomyopathy, and secondly, patients with non-ischaemic cardiomyopathy have a worse prognosis than their counterparts with IHD. The aetiology of CHF may therefore be a confounding factor in this analysis, and it would be interesting to see the effect of AF and LBBB analysed separately for the ischaemic and non-ischaemic subgroups of patients. ...
http://www.eurheartj.org/cgi/content/abstract/23/21/1692
Cumulative effect of complete left bundle-branch block and chronic atrial fibrillation on 1-year mortality and hospitalization in patients with congestive heart failure. A report from the Italian network on congestive heart failure (in-CHF database)
Abstract
Background Many clinical variables have been proposed as prognostic factors in patients with congestive heart failure. Among these, complete left bundle-branch block and atrial fibrillation are known to impair significantly left ventricular performance in patients with congestive heart failure. However, their combined effect on mortality has been poorly investigated. The aim of this study was to determine whether left bundle-branch block associated with atrial fibrillation had an independent, cumulative effect on mortality for congestive heart failure.
Methods and Results We analysed the Italian Network on congestive heart failure (IN-CHF) Registry that was established by the Italian Association of Hospital Cardiologists in 1995. One-year follow-up data were available for 5517 patients. Complete left bundle-branch block and atrial fibrillation were associated in 185 (3·3%) patients. In this population the cause of congestive heart failure was dilated cardiomyopathy (38·4%), ischaemic heart disease (35·1%), hypertensive heart disease (17·3%), and other aetiologies (9·2%). This combination of electrical defects was associated with an increased 1-year mortality from any cause (hazard ratio, HR: 1·88; 95% CI 1·37–2·57) and sudden death (HR: 1·89; 95% CI 1·17–3·03) and 1-year hospitalization rate (HR: 1·83; 95% CI 1·26–2·67).
Conclusions In patients with congestive heart failure, the contemporary presence of left bundle-branch block and atrial fibrillation was associated with a significant increase in mortality. This synergistic effect remained significant after adjusting for clinical variables usually associated with advanced heart failure. We can conclude that this combination of electrical disturbances identifies a congestive heart failure specific population with a high risk of mortality. Copyright 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved
http://adam.about.com/reports/000013_4.htm
...Conditions Associated with Left-Side Heart Failure and Their Effect on Severity
Left-side heart failure tends to be more severe than right-side heart failure, particularly when it is associated with the following conditions:
- Coronary artery disease.
- HIV infection.
- Amyloidosis.
- Chemotherapy with doxorubicin.
The outlook is better in patients with left-side heart failure associated with the following: - Idiopathic cardiomyopathy (the cause is unknown).
- Heart failure due to childbirth.
...Other Conditions Associated with Increased Severity in Heart Failure
Weight Issues. If heart failure patients are overweight to begin with, their condition tends to be more severe. Once heart failure develops, however, an important indicator of a worsening condition is the occurrence of cardiac cachexia, which is unintentional rapid weight loss (a loss of at least 7.5% of normal weight within six months).
Impaired Kidney Function. In one study of patients with advanced heart failure, impaired kidney function was the most important indicator for a poor outlook, even more so than heart function itself. (In the study, impaired kidney function was not associated with heart failure.)
Congestion (Fluid Buildup). According to one study, patients with severe symptoms who have congestion (fluid buildup) have poorer survival rates than those without fluid build up. In fact, two-year survival rates are 87% in those who were congestion-free compared to 41% to 67% in patients with various signs of congestion (e.g., swelling, difficulty breathing when lying down, weight gain from fluid buildup).
Atrial Fibrillation. This abnormal rhythm is a rapid quivering beat in the upper chambers of the heart. It is a major cause of stroke and very dangerous in people with heart failure.
Left Bundle Branch Block. Left bundle-branch block is an abnormality in electrical conduction in the heart. It develops in about 30% of heart failure patients and is a major risk factor for serious adverse heart events.
Sleep Apnea. With this disorder a person stops breathing during the night, perhaps hundreds of times, usually for periods of 10 seconds or longer. It is a very strong risk factor for heart failure, and patients with apnea have a higher mortality rate than those without it.
Depression. The presence of depression indicates a poorer outlook. Studies indicate that depression may have adverse biologic effects on the immune and nervous systems, blood clotting, blood pressure, blood vessels, and heart rhythms.
Seasonal and Daily Patterns. More emergency room visits and higher mortality rates have been observed during winter months and on Mondays in patients with heart failure. One factor in this higher risk may be sudden and strenuous exertion, particularly snow-shoveling, which is associated with a risk for heart attack in people with heart problems.
This one's an explanation of what LBBB is and why bi-ventricular pacing may help: http://www.brighamandwomens.org/cvcenter/Patient/crt.asp
... Some patients with cardiomyopathy and CHF have an abnormality of the electrical system. The most common abnormality is a delay in electrical conduction through the left bundle branch. This is known as left bundle branch block (LBBB). Because the electrical signal to the left ventricle is delayed by left bundle branch block, the right ventricle begins to contract a fraction of a second before the left ventricle instead of simultaneously. The result is an asynchronous, or uncoordinated contraction of the ventricles. This uncoordinated ventricular contraction further reduces the pumping efficiency of an already weakened heart muscle in CHF patients. It is estimated that up to 40% of patients with cardiomyopathy and CHF have an uncoordinated ventricular contraction caused by electrical delay, most often LBBB. This electrical delay is visible on an electrocardiogram (ECG) as widening of the QRS complex and helps to identify patients who might benefits from CRT. (figure 3)... What is cardiac resynchronization therapy?
The idea behind CRT is simple: restoration of the normal coordinated pumping action of the ventricles by overcoming the delay in electrical conduction caused by bundle branch block (also called resynchronization).This is accomplished by means of a unique type of cardiac pacemaker. Common pacemakers are typically used to prevent symptoms associated with excessively slow heartbeats. The pacemaker continuously monitors the patient's heartbeat and delivers a tiny, imperceptible electrical charge to stimulate the heartbeat when necessary. Most pacemakers typically have 2 electrodes (or leads) one in the right atrium and one in the right ventricle, which permits the pacemaker to maintain the normal coordinated pumping relationship between top and bottom of the heart. These leads are connected to a battery pack (pulse generator) placed under the skin in the upper chest. In addition to the 2 leads (right atrium and right ventricle) used by a common pacemaker, CRT pacemakers have a 3rd lead that is positioned in a vein on the outer surface of the left ventricle. (figure 4) ...What to expect from CRT?
The response to CRT may vary greatly between patients. Scientific study involving more than 2,000 patients worldwide have consistently demonstrated modest improvements in exercise tolerance, CHF class and quality of life in most patients. Though these improvements may be noticed almost immediately in many patients, they may not be fully realized for weeks or months in others. Unfortunately, there are a small number of CHF patients who do not benefit from CRT therapy. Further research is needed to identify those patients who are mot likely to benefit.
And off on a tangent,
http://circ.ahajournals.org/cgi/content/full/103/3/375Clinical Investigation and Reports Sex Differences in the Prognosis of Congestive Heart Failure Results From the Cardiac Insufficiency Bisoprolol Study (CIBIS II)
Abstract
Background—Whether female sex is associated with a better prognosis in patients with congestive heart failure (CHF) remains uncertain. The Cardiac Insufficiency Bisoprolol Study (CIBIS) II showed that bisoprolol reduced all-cause mortality and morbidity rates in CHF patients treated with diuretics and ACE inhibitors. We examined whether survival was different in men (n=2132) and women (n=515) enrolled in CIBIS II. Methods and Results—Women differed from men with regard to age, NYHA functional classification, primary cause of CHF, and risk factors such as left bundle-branch block. After adjustment for baseline differences, the probability of all-cause mortality was significantly reduced by 36% in women compared with that in men (hazard ratio 0.64, 95% CI 0.47 to 0.86, P=0.003). Women also had a 39% reduction in cardiovascular deaths (hazard ratio 0.64, 95% CI 0.45 to 0.91, P=0.01) and a 70% reduction in deaths from pump failure (hazard ratio 0.30, 95% CI 0.13 to 0.70, P=0.005) compared with men. Kaplan-Meier survival analysis revealed a significant reduction in all-cause mortality among women treated with bisoprolol compared with men (6% versus 12% P=0.01) but not among women treated with placebo (13% versus 18%, P=0.10). However, this sex/ß-blocker effect was not significant in multivariate analysis. Conclusions—These results indicate that regardless of ß-blocker treatment and baseline clinical profile, female sex is a significant independent predictor of survival in patients with CHF.
