The ventriculophasic response: relationship to sinus arrhythmia and the duration of interposed QRS complexes.

BACKGROUND: The ventriculophasic response (VR) refers to shortening of sinus cycle length during heart block when a QRS complex is interposed between 2 P waves. Our purpose was to analyze its relationship to respiratory sinus arrhythmia (SA) and to compare VR in relation to paced versus intrinsic QRS complexes. METHODS: Patients with advanced heart block had their pacer devices temporarily programmed to ventricular inhibited mode at 30 ppm. In 35 subjects, we analyzed VR and SA before, during and after 3 cycles of deep breathing. In 16 other patients we compared VR in the presence of paced versus narrower intrinsic QRS complexes. RESULTS: The magnitude of P-P interval shortening surrounding QRS complexes during inspiration correlated with SA (r = 0.36, P = 0.03). The prevalence of VR increased from 37% at baseline to 77% of subjects during deep breathing (P = 0.02). The mean P-P interval shortening was greater surrounding intrinsic QRS complexes than paced QRS complexes (3.6 ± 3.6% vs. 1.4 ± 1.1%, P = 0.02). The prevalence of VR increased from 25% during paced rhythm to 56% when intrinsic complexes were present. CONCLUSION: VR, like SA, increases with deep breathing and likely reflects intact parasympathetic nervous system function. Its increase in the presence of narrower beats suggests it may reflect ventricular synchrony.

Prognostic value of cardiopulmonary exercise testing in cardiac patients with atrial fibrillation.

Parameters obtained from cardiopulmonary exercise testing (CPX) are recognized for their high prognostic value in predicting future cardiac events in cardiac patients. Our group compared the prognostic value of CPX parameters between patients with sinus rhythm (SR) and patients with atrial fibrillation (AF).Peak O2 uptake (VO2), the ratio of the increase in VO2 to the increase in work rate (ΔVO2/ΔWR), and the slope of the increase in ventilation to the increase in CO2 output (VE-VCO2 slope) were obtained from CPX in 72 AF patients and 478 SR patients. The prognostic values of these indices were compared between the two groups.Six cardiac deaths and 25 cardiac events were observed in the AF group and 9 cardiac deaths and 96 cardiac events were observed in the SR group, over a prospective follow-up period of 1,192 days. The percentages of cardiac deaths and cardiac events were higher in the AF group than in the SR group. In a multivariate Cox proportional hazards analysis, peak VO2 was identified as a sole significant predictor of cardiac death and cardiac events in SR patients and VE-VCO2 slope was identified as a sole significant predictor of cardiac death and cardiac events in AF patients.Our results suggest that the VE-VCO2 slope is strongly predictive of future cardiac events in patients with AF and that peak VO2 is strongly predictive of future cardiac events in SR patients.

Pacemaker therapy for early and late sinus node dysfunction in orthotopic heart transplant recipients: a single-center experience.

BACKGROUND: Sinus node dysfunction (SND) is a well-known early complication of orthotopic heart transplantation (OHT). Its incidence over the lifetime of transplant recipients is less well characterized. The goal of this study was to determine the incidence and timing of SND treated with a permanent pacemaker in a large cohort of OHT recipients. METHODS: The databases of the Yale University Heart Transplant and Electrophysiology Services were reviewed and cross referenced. Patients who received pacemakers for SND were identified for analysis. A total of 241 patients underwent OHT using biatrial anastamoses from 1984 to 2006. Two hundred sixteen patients, 149 men and 55 women, mean age 50.2 +/- 11.6 years, survived > 5 days post-OHT. These, minus 12 lost to follow-up, were included in the analysis. RESULTS: These 204 patients were followed in the Yale Heart Transplant Clinic and had yearly electrocardiograms and 24-hour ambulatory monitoring. Of these patients, 24 (four female, 20 male, mean age at transplant 49 +/- 12 years) were felt to have clinically significant SND and received a pacemaker. Fourteen patients received pacemakers within 30 days of OHT; 10 patients received pacemakers 45 to 4,329 days after OHT. CONCLUSIONS: Although frequently seen as an early complication of OHT, SND remains a risk throughout the lifetime of OHT recipients. Its mechanism is likely multifactorial, and whether this risk can be mitigated over the long term by newer techniques such as bicaval anastamoses remains to be established.

Atrial vs. dual-chamber cardiac pacing in sinus node disease: a register-based cohort study.

AIMS: In patients with sinus node disease, dual-chamber pacing (DDD) possibly results in adverse effects on the ventricular function. We have compared the incidence of cardiovascular morbidity and mortality in patients with sinus node disease and with atrioventricular (AV) synchronous pacemakers, DDD vs. atrial pacing (AAI). METHODS AND RESULTS: A nation-wide population-based cohort of 8777 patients with AAI- or DDD-mode pacemakers was followed during 12 years. The cohort was linked to national healthcare and census registers. Patients with DDD pacing and without any pre-implant admission for atrial fibrillation or flutter had an increased risk of post-implant fibrillation or flutter, in relation to corresponding AAA patients [hazard ratio (HR) = 1.30; 95% confidence interval (CI) 1.10-1.52]. A slight increase in the risk of any cardiovascular disease (HR = 1.07; CI, 1.00-1.15), and all-cause mortality (HR = 1.12; CI, 1.00-1.25), was seen among DDD patients, in relation to AAI patients, but there was no significant difference in the risk of ischaemic or unspecified stroke (HR = 1.14; CI, 0.94-1.37). Among DDD patients, the all-cause mortality did not differ from the general population [standardized mortality ratio (SMR) = 1.04; CI, 0.98-1.11]. Patients with AAI, however, had a decreased all-cause mortality risk (SMR = 0.89; CI, 0.82-0.97). CONCLUSION: Our results support AAI as the preferred mode of pacing in patients with sinus node disease, and a normal AV node function.

[Female gender is an independent predictor of in-hospital mortality in patients with ST segment elevation acute myocardial infarction treated with primary angioplasty]. / El género femenino es un predictor independiente de la mortalidad intrahospitalaria en pacientes con infarto agudo de miocardio con elevación del segmento ST revascularizado mediante una angioplastia primaria.

OBJECTIVE: The aim of this study was to determine the influence of gender on in hospital outcome in patients with ST-segment elevation myocardial infarction (STEMI) who underwent primary angioplasty (PA). DESIGN AND SCOPE: Prospective study of a cohort of patients consecutively admitted to the Coronary Unit of a tertiary hospital in the period of January to October 2004 with the diagnoses of IAMEST and treated with PA. PATIENTS: Consecutive sample of 86 patients with this diagnosis divided into two groups based on sex: 52 men and 34 women. MAIN VARIABLES OF INTEREST: In both groups, we analyzed the baseline clinical-demographic characteristics, extension of the coronary disease (ECD), success of the PA, appearance of heart failure (HF) and in-hospital mortality in the first 28 days after admission. We analyzed predictors of mortality in a multivariate model. RESULTS: The women were older (70+/-8 versus 65+/-11; p=0.02) and had greater prevalence of diabetes (37% versus 18%; p=0.002) and hypertension (58% versus 37%; p<0.001) than the men while the men had greater frequency of smoking (34% versus 22%; p=0.001). There were no differences in the presence of hyperlipidemia, ECD or the success of PA. Women had a higher incidence of HF on admission (22% versus 12%; p=0.01) and in-hospital mortality (17% versus 8%; p=0.002). In the multivariate analyses, female sex and HF on admission continued to be predictors of in-hospital mortality. CONCLUSIONS: In our study, female gender was an independent predictor of in-hospital mortality in patients with IAMEST treated with PA.

A randomized comparison of amiodarone and class IC antiarrhythmic drugs to treat atrial fibrillation in patients paced for sinus node disease: the Prevention Investigation and Treatment: A Group for Observation and Research on Atrial arrhythmias (PITAGORA) trial.

BACKGROUND: Rhythm control is an important goal in the treatment of recurrent atrial tachyarrhythmias (AT). The PITAGORA study was a randomized trial in patients paced for sinus node disease (SND), designed to test the noninferiority of class IC antiarrhythmic drugs (AADs) to amiodarone in terms of a primary end point composed of death, permanent AT, cardiovascular hospitalization, atrial cardioversion, or AAD change. METHODS: Randomization was stratified to assign 2 patients to amiodarone and 2 patients to class IC AADs: propafenone or flecainide. One hundred seventy-six patients (46% men, 72 +/- 8 years) were enrolled. Device diagnostics continuously monitored AT recurrences and duration. RESULTS: In a mean follow-up of 20 +/- 9 months, the primary end point occurred in 23 (30.7%) of 75 class IC patients and in 28 (40.0%) of 70 amiodarone patients. The absolute difference in the end point incidence (-9.3%; 95% CI between 3.7% and -22.3%) confirmed the noninferiority of class IC to amiodarone (P = .007). Kaplan-Meier 1-year freedom from AT episodes >10 minutes, 1 day, and 7 days was 40%, 73%, and 91% for amiodarone and 28%, 78%, and 86% for class IC AADs (P = nonsignificant). CONCLUSIONS: In patients paced for SND and suffering from AT, class IC AADs proved not to be inferior to amiodarone in terms of the primary composite end point described or end points which were differently composed of mortality, efficacy, or AAD side effects. The AADs studied also showed similar results in terms of symptoms, quality of life, and freedom from AT recurrences.

Sometimes higher heart rate variability is not better heart rate variability: results of graphical and nonlinear analyses.

OBJECTIVE: To determine the prevalence and effect on traditional heart rate variability (HRV) indices of abnormal HRV patterns in the elderly. METHODS: Hourly Poincaré plots and plots of spectral HRV from normal-to-normal interbeat intervals and hourly nonlinear HRV values were examined in a subset of 290 consecutive participants in the Cardiovascular Health Study. Only subjects in normal sinus rhythm with > or = 18 hours of usable data were included. Eligible subjects were 71 +/- 5 years. During 7 years of follow-up, 21.7% had died. Hours were scored as normal (0), borderline (0.5), or abnormal (1) from a combination of plot appearance and HRV. Summed scores were normalized to 100% to create an abnormality score (ABN). Short-term HRV versus each 5th percentile of ABN was plotted and a cutpoint for markedly increased HRV identified. The t-tests compared HRV for subjects above and below this cutpoint. Cox regression evaluated the association of ABN and mortality. RESULTS: Of 5,815 eligible hourly plots, 64.4% were normal, 14.5% borderline, and 21.1% abnormal. HR, SDNN, SDNNIDX, ln VLF and LF power, and power law slope did not differ by the cutpoint for increased short-term HRV, while SDANN and ln ULF power were significantly lower for those above the cutpoint. However, many HRV indices including LF/HF ratio and normalized LF and HF power were significantly different between groups (P < 0.001). Increased ABN was significantly associated with mortality (P = 0.019). Despite similar values for many HRV indices, being in the group above the cutpoint was significantly associated with mortality (P = 0.04). CONCLUSIONS: Abnormal HR patterns that elevate many HRV indices are prevalent among the elderly and associated with higher risk of mortality. Consideration of abnormal HRV may improve HRV-based risk stratification.

Association of prolonged QRS duration with death in a clinical trial of pacemaker therapy for sinus node dysfunction.

BACKGROUND: Prolonged QRS duration (QRSd) is an important prognostic indicator for death and heart failure hospitalization in patients with systolic heart failure. The relationship of baseline QRSd to death and heart failure hospitalization in patients with sinus node dysfunction who require pacemaker therapy is unknown. METHODS AND RESULTS: Baseline QRSd from 12-lead ECGs before pacemaker implantation were analyzed in the Mode Selection Trial (MOST), a 6-year, 2010-patient randomized trial of dual-chamber versus ventricular pacing in sinus node dysfunction. Baseline QRSd was > or =120 ms in 23.4% of patients and was associated with older age, lower ejection fraction, cardiomyopathy, and prior heart failure. Adjusted Cox models demonstrated baseline QRSd > or =120 ms was a strong independent predictor of death (hazard ratio [95% CI] 1.35 [1.07, 1.70], P=0.010) but not heart failure hospitalization. The risk of death increased with increased QRSd from 60 to 120 ms (P=0.002 and hazard ratio [95% CI] 1.14 [1.05, 1.23] for 10-ms increase in this range) after adjustment for other death predictors. CONCLUSIONS: Baseline QRSd > or =120 ms was associated with increased risk of death during pacemaker therapy for sinus node dysfunction.

Complications arising after implantation of DDD pacemakers: the MOST experience.

The purpose of this study was to characterize the incidence, time course, frequency, and spectrum of acute and chronic complications arising from dual-chamber pacemaker implantation. This information may serve as a benchmark when comparing complication rates for dual-chamber pacemaker implantation with those for biventricular pacemaker implantation.

[Arrhythmias in patients with congenital heart disease and their impact on prognosis]. / Arrhythmien bei Patienten mit angeborenen Herzfehlern und Bedeutung für die Prognose.

Patients with congenital heart disease have an increased chance to suffer from brady- as well as tachyarrhythmias. The impact of these on quality of life, morbidity and mortality is more often imperative as compared to heart-healthy individuals. The substrate for these may be either congenital or acquired. Improvements of the surgical management of these patients have led, on the one hand, to improved survival rates with prolonged life expectancy within the last 2 decades, which on the other hand provided the basis for a higher rate of acquired cardiac arrhythmias. Together, this not only challenges diagnostics and therapy but also the prognostic relevance of these arrhythmias. The therapeutic strategies and prognostic markers have until now mostly been based on retrospective studies limited by the low number of patients and inhomogeneous patient selection. Despite these limitations, an increased risk of sudden cardiac death has been substantiated for certain patient groups, e.g., those operated on by the Mustard- or Senning procedures in patients with transposition of the great arteries and patients operated on with correction of the tetralogy of Fallot. However, until now it has not been possible to identify reliable markers for establishing the risk on an individual basis within these patient cohorts. For achieving reliable data on the symptomatic and prognostic effects of present-day--as well as new-coming--therapeutic strategies, it is mandatory to perform prospectively based, randomized multicenter studies. Furthermore, the well-appreciated synergism of hemodynamically and primarily of arrhythmia-based effects on prognosis could potentially be divided into their relative weight to better guide appropriate, substrate-related therapy. In addition, this should help to get better estimates of the risk for sudden cardiac death in different, etiologically homogeneous, groups of patients with congenital heart disease.

Relation between mode of pacing and long-term survival in the very elderly.

OBJECTIVES: This study analyzes the relationship between pacing mode and long-term survival in a large group of very elderly patients (> or = 80 years old). BACKGROUND: The relationship between pacing mode and long-term survival is not clear. Because the number of very elderly who are candidates for pacing is increasing, issues related to pacemaker (PM) use in the elderly have important clinical and economic implications. METHODS: We retrospectively reviewed 432 patients (mean age, 84.5+/-3.9 years) who received their initial PM (ventricular in 310 and dual chamber in 122) between 1980 and 1992. Follow-up was complete (3.5+/-2.6 years). Observed survival was estimated by the Kaplan-Meier method. Age- and gender-matched cohorts from the Minnesota population were used for expected survival. Log-rank test and Cox regression hazard model were used for univariate and multivariate analyses. RESULTS: Patients with ventricular PMs appeared to have poor overall survival compared with those with dual-chamber PMs. Observed survival after PM implantation in high grade atrioventricular block (AVB) patients was significantly worse than expected survival of the age- and gender-matched population (p < 0.0001), whereas observed survival of patients with sinus node dysfunction was not significantly different from expected survival of the matched population (p = 0.413). By univariate analysis, ventricular pacing in patients with AVB appeared to be associated with poor survival compared with dual-chamber pacing (hazard ratio [HR] 2.08; 95% confidence interval [CI] 1.33 to 3.33). After multivariate analysis, this difference was no longer significant (HR 1.41; 95% CI 0.88 to 2.27). Independent predictors of all-cause mortality were number of comorbid illnesses, New York Heart Association functional class, left ventricular depression and older age at implant. Pacing mode was not an independent predictor of overall survival. Older age at implantation, diabetes mellitus, dementia, history of paroxysmal atrial fibrillation and earlier year of implantation were independent predictors of ventricular pacemaker selection. CONCLUSIONS: After PM implantation, long-term survival among very elderly patients was not affected by pacing mode after correction of baseline differences. Selection bias was present in pacing mode in the very elderly, with ventricular pacing selected for sicker and older patients, perhaps partly explaining the apparent "beneficial impact on survival" observed with dual-chamber pacing.

Predictive value of continuous ambulatory electrocardiographic monitoring in elderly people.

OBJECTIVE: To determine the predictive value of findings on continuous ambulatory electrocardiographic monitoring in elderly subjects. DESIGN: Retrospective cohort study. Ten year follow up of randomly selected elderly subjects who participated in ambulatory electrocardiography study in 1982. Mortality data derived from official registers. SETTING: Turku, Finland. SUBJECTS: 480 people aged 65 or older in 1982 who were living in the community, of whom 72% agreed to participate. MAIN OUTCOME MEASURES: Mortality from cardiac and non-cardiac causes during 10 year follow up. RESULTS: In the univariate analysis adjusted for age, risk of death from cardiac causes was increased among those with ventricular ectopy of more than 100 beats during the day (odds ratio 2.6; 99% confidence interval 1.4 to 6.1) or at night (3.3; 1.1 to 9.8) and in those with multifocal ventricular ectopic beats during the day (2.3; 1.0 to 5.0) or night (3.0; 1.3 to 7.1) compared with those with no ventricular ectopy. Sinoatrial pauses exceeding 1.5 seconds during the day (4.5; 1.8 to 11.1) were also associated with excess mortality from cardiac causes. None of the findings on ambulatory electrocardiography predicted death from non-cardiac causes. A further study of explanatory variables in the stepwise logistic regression analysis showed that sinoatrial pauses exceeding 1.5 seconds (4.0; 95% confidence interval 1.8 to 8.9) and night time multifocal ventricular ectopy (2.7; 1.2 to 5.9) predicted excess mortality from cardiac causes independently of age or clinically evident heart disease. CONCLUSION: Daytime sinoatrial pauses exceeding 1.5 seconds and night time multifocal ventricular ectopy in the ambulatory electrocardiogram predict increased mortality from cardiac causes independently of clinically evident cardiac diseases in unselected elderly subjects.

Atrial arrhythmias in dual chamber pacing and their influence on long-term mortality.

A retrospective study of 252 patients who received a DDD pacemaker between October 1982 and December 1990 was performed. During a mean follow-up of 30 months, reprogramming to the VVI mode was necessary in 39 patients (15.5%). Technical problems causing downgrading occurred 15 times, of which 13 problems became permanent. A total number of 24 patients had sustained atrial arrhythmias, including 14 with atrial fibrillation and 10 with atrial flutter. In this group, conversion to sinus rhythm could be obtained in 38%. After 2 years, reliable DDD pacing was maintained in 86% of the surviving patients. The survival after 1 and 2 years was 94% and 89%, respectively, and was not influenced by arrhythmias or technical problems. We conclude that atrial arrhythmias including flutter are the most important reasons for reprogramming to the VVI mode, although in an important number of patients, predominantly those with flutter, restoration of AV synchrony can be obtained. The high number of patients with atrial flutter could imply some role for DDD devices offering the option of antitachycardia pacing. Reprogramming of the pacing mode did not influence mortality.

Morbidity and mortality of patients with sinus node disease: comparative effects of atrial and ventricular pacing.

In patients with sinus node disease (SND), VVI pacing seems an inappropriate method of cardiac stimulation because of its potential adverse hemodynamic and arrhythmic effects. AAI-DDD pacing, preferred because of lower morbidity, may also determine a higher survival rate. We examined retrospectively two groups of patients with SND. Stimulated respectively with VVI pacing (group 1 = 57 patients) and AAI pacing (group 2 = 53 patients). The mean duration of the follow-up interval was 40.1 months for group 1 and 45 months for group 2. Ten patients (17.5%) in the VVI group and five (9.4%) in the AAI died. During the follow-up, in the VVI group three patients developed congestive heart failure and ten developed chronic atrial fibrillation, whereas only one case of heart failure and two with atrial fibrillation have been recorded in the AAI group. Moreover, four patients had embolic complications in group 1. Five patients (9.4%) with AAI pacing were converted to sequential pacing due to the occurrence of second-degree heart block. The statistical analysis was developed by the X2 test for the comparison of the proportion of the events (atrial fibrillation, congestive heart failure, embolic accidents) in the two groups: a significantly higher morbidity (P less than 0.01) was recorded in the AAI group. Survival is also higher in AAI patients, but the survival rate difference, calculated using the Mantel-Cox method, is not statistically significant. The findings of our study show that in SND the superiority of AAI pacing over VVI is statistically significant as far as morbidity is concerned, and we have also noticed an evident but not statistically significant superiority regarding mortality.

Permanent cardiac pacemaker in infants and children.

Between October 1970 and November 1984, 26 infants and children aged 11 days to 18 years (mean 5.7 years) received 42 permanent cardiac pacemakers (26 primary implants, 16 re-implants) for congenital or surgically acquired heart block, bradycardia and sinus node dysfunction. Twenty-two patients had unipolar pacing and 4 bipolar pacing. Of 26 primary implantations, 2 had fixed rate epicardial pacing, 16 ventricular demand pacing (13 epicardial, 3 endocardial), 3 epicardial VAT (P-synchronous) pacing and 5 DDD (universal) pacing (4 epicardial, one endocardial). Fourteen patients required a further 19 operations for change of generators (16), ventricular lead (1), generator site (1) and generator encasing (1). Thirty-day hospital mortality was 11.5% (3/26), of which one death was possibly related to pacing failure. Four patients died during the follow-up period (3 months to 10 years; mean 3.4 years). Sixteen of the 19 survivors achieved complete symptomatic relief, without any medical therapy. Our results indicate that modern cardiac pacemaker systems are safe and reliable, and are associated with major relief of symptoms in this age group.

Mexiletine: double-blind comparison with procainamide in PVC suppression and open-label sequential comparison with amiodarone in life-threatening ventricular arrhythmias.

The antiarrhythmic effects of mexiletine (n = 14) were compared to procainamide (n = 16) by a double-blind parallel protocol in 30 patients (group I) with frequent premature ventricular contractions (PVCs) (greater than 20/hr), and to amiodarone by an open-label sequential approach in 25 patients (mean left ventricular ejection fraction of 32.6 +/- 13.4%) with life-threatening ventricular arrhythmias (group II) resistant to two or more conventional agents. The predetermined end point of therapy in group I patients was met in 6 of 14 (43%) given mexiletine, with 7 (50%) requiring drug discontinuation for severe gastrointestinal or central nervous system side effects and only 3 of 16 patients (19%) given procainamide, with 5 (31%) developing limiting side effects. Increases in dose led to a higher efficacy rate for PVC suppression with a corresponding increase in side effects with mexiletine; with procainamide, the higher dose was not associated with greater PVC suppression. In group II patients, mexiletine was effective in 4 (16%), with one patient discontinuing the drug during long-term therapy; mexiletine was ineffective in 16 (64%) and early side effects developed in 5 (20%). Patients not responding to or not tolerating mexiletine were given amiodarone; 20 of 21 (95%) responded with arrhythmia control after the loading dose. During a mean follow-up period of 2 years, sudden death occurred in two patients, death from heart failure in two, and death from subarachnoid hemorrhage in one patient; 15 (75%) patients are alive and free of arrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural history of sinus node dysfunction after permanent pacemaker implantation.

To explore the natural history of symptomatic sinus node dysfunction after permanent pacemaker implantation, we followed up 71 patients (27 with sinus arrest, 27 with unexplained sinus bradycardia, 14 with the bradycardia/tachycardia syndrome, and three with sinoatrial block) for four to 14 years after placement of a permanent ventricular pacemaker. Survival rates at one, five, and ten years were 88%, 75%, and 70%, respectively. Overall mortality was 31%. Patients with congestive heart failure had significantly lower survival rates than those without (P less than .03). Survival rates were significantly lower in patients with coronary artery disease than in those with conduction system disease only (P less than .01). Fourteen of the 19 patients whose cause of death was known died of cardiovascular disease, ten of complications of coronary artery disease. Thus, survival after pacemaker implantation is adversely and profoundly influenced by underlying cardiovascular disease, particularly coronary artery disease and its complications.

Sinus node dysfunction in 128 patients. A retrospective study with follow-up.

A retrospective study covering all admissions during a 6-year period revealed 128 patients with sinus node dysfunction (SND). The patients were grouped according to the ECG criteria chosen: group I 33 patients with sinus bradycardia, group II 37 with sinoatrial block/sinus arrest, group III 58 with brady-tachy syndrome. Additional heart disease, predominantly ischaemic, was found in 56%. The frequency and severity of symptoms increased from group I to group III. Pacemaker treatment was given to 40% of the cases, while medical treatment alone was successful in 17%. A follow-up including 104 patients was carried out after a mean observation period of approximately three years. Sixteen patients had died. The cause of death may have been SND per se in only one case. Five patients died of apoplectic insults or complications to such. In total, nine possible or proven systemic embolic events were found--all occurring in patients with brady-tachy syndrome. A progression of the ECG abnormality from a lower to a higher group took place in nine patients during the observation period. It is concluded that SND is a condition with a broad clinical spectrum and a stationary or slowly progressive course. In general, it carries a good prognosis. A substantial number of deaths of disabilities in patients with brady-tachy syndrome may be ascribed to systemic embolism. Long-term anticoagulant therapy is proposed in this subgroup of patients with SND.

Sinus arrhythmia in acute myocardial infarction.

Sinus arrhythmia, defined by means of a calculation of variance of the R-R interval on admission to hospital, was present in 73 of 176 patients admitted to a coronary care unit with acute myocardial infarction. These patients had a lower hospital mortality. They tended to have a higher incidence of inferior infarction, and a lower incidence of anterior infarction, and to have smaller infarcts as measured by the Norris index. The main difference between patients with sinus arrhythmia and without sinus arrhythmia related to heart rates on admission to hospital, the patients with the former having slower heart rates at that time.