The frequency and prognostic significance of electrocardiographic abnormalities in clinically normal individuals

Diagnostic assessment of recurrent syncope

The definitive diagnosis of a cardiac arrhythmia as the basis for syncope is made by electrocardiographic monitoring during a syncopal episode. In the absence of this evidence, abnormalities demonstrated by an electrophysiologic study may suggest the etiology of syncope. Cardiac electrophysiologic testing in patients with recurrent syncope should probably be limited to patients with underlying cardiac disease. These patients are at a higher risk for sudden death and have a high incidence of electrophysiologic abnormalities. In particular, ventricular tachycardia may be evoked and specific therapy for this abnormality is associated with remission of syncope. In contrast, electrophysiologic studies in patients with no underlying cardiac disease have a very low yield of abnormal findings in the order of 10-20%, and should be performed only when there are reasons to suspect the presence of arrhythmias. Furthermore, in patients with no underlying cardiovascular disease there is a high spontaneous remission rate of syncope and the late incidence of sudden death is low, and related to the presence of other systemic illnesses. At present, the significance of nonsustained ventricular tachycardia or ventricular fibrillation induced during cardiac electrophysiologic studies in patients with no documented arrhythmias is unknown, and further prospective studies are necessary to define appropriate therapy for these patients. Further investigation is also required to clarify the spontaneous remission rate of syncope, as this information is of vital importance in assessing the success of any therapeutic modality.

Disturbances of cardiac rhythm and conduction in familial amyloidosis with polyneuropathy

Sixteen consecutive patients with familial amyloidosis with polyneuropathy of varying duration and severity underwent 24 hour ambulatory electrocardiographic monitoring. A high incidence of sinus node dysfunction, supraventricular and ventricular arrhythmias, and disturbances of atrioventricular conduction was found. Considerably more arrhythmias and disturbances of conduction were detected by long term electrocardiographic monitoring than by conventional 12 lead electrocardiograms. During a follow up period of three to 14 months five patients needed treatment by a pacemaker, three of them because of symptomatic complete heart block, one because of second degree heart block with heart failure, and one because of symptomatic dysfunction of the sinus node. The tachyarrhythmias did not require specific treatment. Long term electrocardiographic monitoring is a useful adjunct in the evaluation of patients with familial amyloidosis with polyneuropathy as it may detect otherwise unrecognised symptomatic disturbances of heart rhythm. The results may be valid also for other forms of amyloidosis involving the heart.

A prospective evaluation and follow-up of patients with syncope

We prospectively evaluated and followed 204 patients with syncope to determine how often a cause of syncope could be established and to define the prognosis of such patients. A cardiovascular cause was established in 53 patients and a noncardiovascular cause in 54. The cause remained unknown in 97 patients. At 12 months, the overall mortality was 14 +/- 2.5 per cent. The mortality rate (30 +/- 6.7 per cent) in patients with a cardiovascular cause of syncope was significantly higher than the rate (12 +/- 4.4 per cent) in patients with a noncardiovascular cause (P = 0.02) and the rate (6.4 +/- 2.8 per cent) in patients with syncope of unknown origin (P less than 0.0001). The incidence of sudden death was 24 +/- 6.6 per cent in patients with a cardiovascular cause, as compared with 4 +/- 2.7 per cent in patients with a noncardiovascular cause (P = 0.005) and 3 +/- 1.8 per cent in patients with syncope of unknown origin (P = 0.0002). Patients with syncope can be separated into diagnostic categories that have prognostic importance. Patients with a cardiovascular cause have a strikingly higher incidence of sudden death than patients with a noncardiovascular or unknown cause.

Asymptomatic ventricular ectopy. To treat or not to treat?

Ventricular ectopy that is bothersome to the patient warrants treatment, but the asymptomatic cases present the physician with a dilemma of whether or not treatment is justified. In patients free of organic heart disease, antiarrhythmic therapy does not appear to be necessary. Post myocardial infarction (MI) patients should be considered for beta-blocker therapy regardless of the presence of ventricular ectopy. In the post-MI patient with risk factors for sudden death, treatment of complex dysrhythmia may be warranted, despite the lack of documented benefit.

Undiagnosed syncope: search for an arrhythmic etiology

Patients with recurrent, unheralded syncope are often suspected of having intermittent cardiac bradyarrhythmias or tachyarrhythmias. However, syncopal episodes may be infrequent and investigations may yield few or non-specific etiological clues. Therapy may be entirely empirical (pacing or antiarrhythmic drugs) or guided by an abnormality detected that suggests a particular diagnosis. Intracardiac electrophysiological studies may detect conduction abnormalities or provoke arrhythmias but the relationship between these findings and clinical symptoms may be difficult to establish. The recording of the ECG during syncope by repeated ambulatory monitoring or other methods remains the only unequivocal diagnostic technique to establish an arrhythmic etiology.

Electrocardiograms and 13 year cardiovascular mortality in Busselton study

In 2119 unselected Busselton subjects 40 to 79 years of age, the 13 year mortality from cardiovascular disease was significantly higher in those whose initial electrocardiogram showed Q and QS patterns, left axis deviation, ST depression, T wave depression, flat or biphasic T waves, atrial fibrillation or flutter, and ventricular extrasystoles. In angina-free subjects whose electrocardiographic codes occurred in isolation from any other electrocardiographic abnormality, ventricular extrasystoles were associated with significantly higher mortality from cardiovascular disease compared with controls.