Reevaluation of the prognosis of patients with LAD--RBBB

[Historical development of diagnosis of bradyarrhythmias : The early years of clinical electrophysiology in Germany]

The introduction of His bundle electrography by Benjamin Scherlag (New York) in 1969, together with programmed stimulation of the heart by Philip Coumel (Paris) in 1967, and Hein Wellens (Amsterdam) in 1972, were decisive turning points on the way to invasive electrophysiology and the development of an independent, now distinctly interventional subspecialty of cardiology. The main topic of the 1970s was bradycardic arrhythmias, promoted by pacemaker therapy, which had been introduced just over 10 years earlier. The recording of the potentials of the bundle of His and other recording locations in the atria and ventricles allowed a differentiated assessment of the excitation process and the refractory periods. High-rate atrial stimulation to determine sinus node recovery time and premature stimulation to determine sinoatrial conduction time were developed to analyze sinoatrial node function. This article describes the introduction of His bundle electrography in a gradually increasing number of centers in Germany and their scientific contribution.

All-Cause Mortality for Life Insurance Applicants with the Presence of Bundle Branch Block

Objective.-To determine the all-cause mortality of life insurance applicants who have a bundle branch block. Background.-Bundle branch block is an electrocardiographic pattern that has variable prognostic implications. Research studies have shown that both left and right bundle branch block are associated with increased mortality among cases that have heart disease. In the general population and life insurance applicant population, the prevalence of bundle branch block is relatively low, and its effects on long-term prognosis are not as well established. Methodology.-Life insurance applicants with reported bundle branch block were extracted from data covering United States residents between October 2009 and October 2016. Information about these applicants was matched to the Social Security Death Master (SSDMF) file for deaths occurring from 2009 to 2012 and to another commercially available death source file (Other Death Source, ODS) for deaths occurring from 2009 to 2016 to determine vital status. Actual to expected (A/E) mortality ratios were calculated using the Society of Actuaries 2015 Valuation Basic Table (2015VBT), select and ultimate table (age last birthday). All expected bases were not smoker distinct. Confidence bands around these mortality ratios were calculated. The variables of interest were applicant age, gender, location of the bundle branch block, and the presence of cardiac or cardiovascular conditions. Results.-There were 258,529.85 person-years exposure for applicants with bundle branch block. Of the applicants, 57.2% had right bundle branch block. Of person-years exposure, 11.5% had a cardiac condition along with the bundle branch block, and 4.4% had an underlying cardiovascular condition. Female mortality ratios were higher than those for males, but due to the low number of deaths, this difference was not significant. Left bundle branch block mortality ratios (1.01) were 1.4 times higher than those with right (0.74). Those applicants with a cardiac condition along with their bundle branch block had between 1.6 to 1.8 times the mortality ratio depending on the bundle branch block location, and those with a cardiovascular condition had between 1.5 to 1.7 times the mortality ratio over those applicants with just bundle branch block alone. Conclusion.-The presence of bundle branch block in an insurance applicant may be associated with increased all-cause mortality. In this study, life insurance applicants overall had a mortality slightly lower than the expected mortality based on the 2015 VBT. However, applicants with bundle branch block and a cardiac or cardiovascular comorbid condition had a significantly higher mortality ratio.

Association of cardiac implantable electronic devices with survival in bifascicular block and prolonged PR interval on electrocardiogram

PURPOSE

Bifascicular block and prolonged PR interval on the electrocardiogram (ECG) have been associated with complete heart block and sudden cardiac death. We sought to determine if cardiac implantable electronic devices (CIED) improve survival in these patients.

METHODS

We assessed survival in relation to CIED status among 636 consecutive patients with bifascicular block and prolonged PR interval on the ECG. In survival analyses, CIED was considered as a time-varying covariate.

RESULTS

Average age was 76 ± 9 years, and 99% of the patients were men. A total of 167 (26%) underwent CIED (127 pacemaker only) implantation at baseline (n = 23) or during follow-up (n = 144). During 5.4 ± 3.8 years of follow-up, 83 (13%) patients developed complete or high-degree atrioventricular block and 375 (59%) died. Patients with a CIED had a longer survival compared to those without a CIED in the traditional, static analysis (log-rank p < 0.0001) but not when CIED was considered as a time-varying covariate (log-rank p = 0.76). In the multivariable model, patients with a CIED had a 34% lower risk of death (hazard ratio 0.66, 95% confidence interval 0.52-0.83; p = 0.001) than those without CIED in the traditional analysis but not in the time-varying covariate analysis (hazard ratio 1.05, 95% confidence interval 0.79-1.38; p = 0.76). Results did not change in the subgroup with a pacemaker only.

CONCLUSIONS

Bifascicular block and prolonged PR interval on ECG are associated with a high incidence of complete atrioventricular block and mortality. However, CIED implantation does not have a significant influence on survival when time-varying nature of CIED implantation is considered.

Mitochondrial DNA deletion diagnosed by analysis of an endomyocardial biopsy specimen from a patient with Kearns-Sayre syndrome and complete heart block

Defects of mitochondrial DNA have been found at necropsy in the myocardium of patients with Kearns-Sayre syndrome. A patient with characteristics typical of Kearns-Sayre syndrome and a complete heart block is described. Southern blot analysis showed a deletion of 3.3 kb in the mitochondrial DNA in an endomyocardial biopsy specimen and in skeletal muscle. The deletion led to the disappearance of the genes for four transfer RNAs and four subunits of complex I (NADH:ubiquinone oxidoreductase) in the mitochondrial respiratory chain. The defect could not be demonstrated in whole blood despite amplification of the mitochondrial DNA region of interest by the polymerase chain reaction technique. There can be heteroplasmy--that is, normal and abnormal mitochondrial DNA populations in one cell--in different tissues, and the degree of heteroplasmy may be crucial in the development of organ-specific symptoms. This patient raises the possibility that some tissues can be specifically enriched with mitochondria with DNA defects and emphasises the need for elective sampling of the target tissue and polymerase chain reaction technique to exclude these defects. The role of mitochondrial DNA defects in idiopathic cardiomyopathies could perhaps be studied by analysis of mitochondrial DNA from endomyocardial biopsy specimens.

Excess mortality and morbidity associated with right bundle branch and left anterior fascicular block

Excess mortality and morbidity associated with right bundle branch and left anterior fascicular block were evaluated in 108 patients with block (age 74 +/- 10 years, 69% male) and 108 age- and sex-matched control patients with normal conduction. Clinical characteristics were similar initially except for more congestive heart failure in patients with block. Life table analysis revealed a higher 12 year mortality with block, even after omitting patients with moderate or severe congestive heart failure (risk ratio 1.47, p less than 0.05). Compared with control subjects, the group of patients with block had more sudden death and deaths of unknown cause, but a similar number of noncardiac and diagnosed cardiac deaths. More patients with block developed new second and third degree atrioventricular block or new overt coronary artery disease, but this finding did not support prophylactic pacing in asymptomatic patients. The importance of internal controls in assessing the natural history of clinical and electrocardiographic abnormalities is emphasized.

Should this patient be paced? An indication for His bundle study: syncope, a normal P-R interval and a narrow QRS

This report describes a patient who presented with transient central nervous system symptoms of unknown etiology with an electro-cardiogram exhibiting a narrow QRS complex and normal. P-R interval. The decision to implant a permanent VII pacemaker was made on the basis of a His bundle study that revealed significant prolongation of the HV interval. The successful clinical outcome re-emphasizes the clinical usefulness of electrophysiological investigation in patients with syncope of undetermined etiology.

Myocardial ultrastructure and the development of atrioventricular block in Kearns-Sayre syndrome

A right ventricular endomyocardial biopsy specimen from a 30-year-old male with chromic progressive external ophthalmoplegia, retinal pigmentation and complete atrioventricular block (Kearns-Sayre syndrome) was examined in the electron microscope. There was a proliferation of mitochondria between the myofibrils and beneath the sarcolemma. Many of the mitochondria showed morphologic abnormalities not previously described in this condition. There were associated accumulations of glycogen. A similarly affected female with left anterior hemiblock developed complete atrioventricular block at age 26 years, Despite the ultrastructural changes, clinically detectable myocardial disease is not a feature of Kearns-Sayre syndrome. However, intraventricular conduction defects show an unusually rapid progression to potentially fatal complete atrioventricular block and are an indication for prophylactic cardiac pacing.