Author + information
- Received October 7, 1986
- Revision received January 26, 1987
- Accepted February 19, 1987
- Published online August 1, 1987.
- Ryszard B. Krol, MD1,*,
- Fred Morady, MD, FACC1,
- Greg C. Flaker, MD, FACC1,
- Lorenzo A. DiCarlo Jr., MD1,
- Jeffrey M. Baerman, MD1,
- John Hewett, PhD1 and
- Michael de Buitleir, MB1
- ↵*Address for reprints:Ryszard B. Krol, MD, University of Missouri Medical School, MA432C, Medical Science Addition, Columbia, Missouri 65212.
To assess whether the level of risk of having significant electrophysiologic abnormalities can be determined, 29 clinical variables were analyzed in 104 patients with unexplained syncope who underwent electrophysiologic testing. A positive electrophysiologic study was defined as: 1) a sinus node recovery time ≥3 seconds; 2) HV interval ≥100 ms; 3) infranodal block during atrial pacing; 4) unimorphic ventricular tachycardia; and 5) supraventricular tachycardia associated with hypotension.
Thirty-one patients had a positive study, with inducible ventricular tachycardia being the most common finding (71% of positive studies). A left ventricular ejection fraction ≤0.40 was the most powerful predictor of a positive electrophysiologic study (p < 0.00001), followed by the presence of bundle branch block (p < 0.00003), coronary artery disease (p < 0.00003), remote myocardial infarction (p < 0.00006), use of type 1 antiarrhythmic drugs (p < 0.0003), injury related to loss of consciousness (p < 0.01) and male sex (p < 0.01).
A negative electrophysiologic study was associated with an ejection fraction >0.40 (p < 0.00001), the absence of structural heart disease (p < 0.00001), a normal electrocardiogram (ECG) (p < 0.0001) and normal ambulatory ECG monitoring (p < 0.0001). The probability of a negative study increased as the number and duration of syncopal episodes increased.
The results of electrophysiologic testing could be predicted with a probability (p) value ≥0.99 in 51% of patients who had a negative study and with a probability value ≥0.95 in 52% of those who had a positive study. Therefore, on the basis of clinical variables, a majority of patients with unexplained syncope can be stratified into subgroups with high and low probability of having an electrophysiologic abnormality that is likely to be related to syncope. This allows for more cost-effective use of electrophysiologic studies.
- Received October 7, 1986.
- Revision received January 26, 1987.
- Accepted February 19, 1987.
- American College of Cardiology Foundation