Clinical significance of second degree Wenckebach type sinoatrial block identified during Holter monitoring in patients with symptoms suggestive of arrhythmia.

AIMS: To determine the clinical significance of the sinoatrial block II° of the Wenckebach type (block W) identified during Holter monitoring. METHODS AND RESULTS: The study included 300 patients (mean age 54 ± 17 years; 130 women) with symptoms suggestive of arrhythmia who underwent Holter monitoring. Block W was identified by a dedicated computer program and subsequently confirmed by a cardiologist. Block W was diagnosed in 88 patients (29%). It occurred only during sleep in 37 (12%) patients and during both daytime activity and sleep in 51 (17%) patients. Block W only during sleep happened predominately in young patients aged between 20 and 30 years, whereas episodes that occurred during both daytime and sleep were found mainly in patients between 60 and 70 years of age. Prospective observation time averaged 41 ± 11 months, and the time to the diagnosis of sinus node disease was 26 ± 10 months. Cox multivariate analyses showed that block W during both daytime and sleep is an independent predictor for the future diagnosis of sinus node disease [hazard ratio-13.6 (5.2-35.5); P < 0.0001]. Age-specific analyses confined this effect to the patients ≥50 years of age. The results also suggest that in patients ≥50 years of age block W during both daytime and sleep may be related to a significant improvement in survival [hazard ratio-0.03 (0.007-0.16); P < 0.0001]. CONCLUSION: Block W during daytime activity in patients with symptoms suggestive of arrhythmia indicates an increased likelihood of the future diagnosis of sinus node disease.

Sinus node disease. Current concepts in diagnosis and therapy.

Sinus node disease (SND) encompasses a number of abnormalities of sinus impulse generation and transmission within the atria and may lead to both bradyarrhythmias and tachycardias. Such abnormalities may be due to primary atrial electrophysiological abnormalities, or be secondary to drugs or abnormal autonomic control. The diagnosis may be readily established from the surface ECG or Holter recordings in many cases, but invasive electrophysiological study or assessment of the effects of autonomic blockade may be required in symptomatic patients in whom the diagnosis is suspected but not confirmed by simple electrocardiographic monitoring. Treatment should be restricted to those patients in whom clear correlation between symptoms and electrocardiographic or electrophysiological abnormalities has been established. Although a number of pharmacological agents have been assessed, the treatment of bradyarrhythmias should be permanent pacing. There is now substantial evidence that physiological (atrial or dual chamber) pacing reduces atrial arrhythmias, systemic embolisation, progression to heart failure and mortality, compared to single chamber ventricular pacing. Antiarrhythmic therapy may be required to control atrial tachyarrhythmias if they persist following pacing. In patients with uncontrolled atrial arrhythmias, especially those with ventricular pacemakers, long term oral anticoagulation should be considered to reduce the risk of systemic embolisation which is a common complication in patients with the bradycardia/tachycardia syndrome.

Symptomatic sinus node disease: natural history after permanent ventricular pacing.

Fifty-nine patients between the ages of 13 and 88 with sinus node disease, who received a permanent ventricular pacemaker between 1965 and 1976 at one institution, were followed to determine the natural history of the disorder after permanent pacing. Nineteen had ischemic heart disease, six had primary myocardial disease, and eight valvular heart disease. In 26, no etiology for the arrhythmia was apparent. The one- and five-year survival was 85.5% and 73.1%, respectively. Patients with underlying heart disease had a significantly poorer survival when compared to those without (58% versus 94% at 36 months) and all but 3 of 13 deaths in the first 36 months were in those with ischemic heart disease. There was a distinct trend toward poor survival in those with heart failure prior to pacemaker implant and those over age 65. Patients with sinus bradycardia alone did best (91% survival three years after implant), while those with bradycardia-tachycardia syndrome and those with sinoatrial arrest alone did distinctly worse (76% and 65% survival at three years, respectively). Twelve of 18 deaths were due to progression of underlying heart disease. The long-term prognosis with symptomatic sinus node disease can be predicted in part by (1) etiology of the underlying heart disease, (2) pre-implant arrhythmia, and (3) ventricular function prior to implant.

The long-term prognosis for patients with sinoatrial block treated with permanent pacemaker.

Fifty patients with SA block have been treated with permanent pacing and followed up for 1-14 years. Survival after one, two, five and eight years was calculated to 94, 85, 64 and 48%, respectively. These figures indicate an excess yearly mortality in the first five years of 4-5% compared with a population of the same age and sex. Analysis of the survival curves shows that the excess mortality is caused by coexisting diseases, primarily coronary heart disease with previous myocardial infarction and valvular heart disease.