ABSTRACTS

SIGNIFICANCE OF VENTRICULAR ARRHYTHMIAS ON LOW LEVEL EXERCISE TESTING TWO WEEKS AFTER ACUTE MYQCARDIAL INFARCTION

Francis M. Weld, MD, FACC; J. Thomas Bigger, Jr., MD, FACC; Linda M. Rolnitzky;. King-Lee Chu, M.D., Columbia University, New York, New York

Exercise test ventricular arrhythmias have little prognostic significance in patients with chronic ischemic heart disease. To assess the significance of exercise test arrhythmias in 300 patients with recent acute myocardial infarction, we recorded the ECG for nine minutes before, during and after a standardized nine minute treadmill exercise test prior to hospital discharge. Exercise test ventricular premature depolarizations (VPD) occurred in 37% of patients and were only weakly associated (p greater than 0.05) with left ventricular failure in the Cardiac Care Unit or at exercise, and not at all associated with horizontal or downsloping ST segment depression of at least 0.1 mV in any of ECG leads aVf, V2 or V5 during or after exercise. The one-year cardiac death rate was 9%, and was higher in patients with both pre-exercise and exercise VPD (20%) than in patients with either pre-exercise or exercise VPD (9%) or in patients without exercise test VPD (5%). We conclude that submaximal exercise test VPD in patients convalescing from acute myocardial infarction are not associated with exercise ischemia but are nonetheless strongly predictive of post-hospital cardiac death.

CAN VENTRICULAR ECTOPIC ACTIVITY ENHANCE THE LDCALISATION OF EXERCISE INDUCED ISCHAEHIA. Phyllis Holt,MRCP, Paul Curry,HD, David Roper,MRCP,Michael Maisey,HRCP, Cardiac Dept., Guy's Hospital, London. The standard 12 lead ECG can localise the site of origin of ventricular ectopic rhythms. An atlas of ectopic appearances from individual ventricular sites has been drawn. In view of the relationship between myocardial ischaemia and ventricular arrhythmias we were interested in their comoarative anatomv. Two hundred and ten oatients underwent maximal exercise testing prior to thallium scin- tioraphv. All 12 leads of the ECG were recorded simul- taneouslv at rest, during and post exercise. Thallium 201 was injected intravenously at maximal exercise and the patients scanned. Twenty nine patients of the 210 had ventricular arrhythmias on exercise. Nineteen of these patients had otherwise negative exercise tests and of these 17 had coronary artery disease on scintigraphy. One patient had hypertrophic cardiomyopathy and the other congestive cardiomyopathy. Localisation of the arrhythmias was possible in every patient. Those with reversible posterior (circumflex) defects had c(5BB ectopics with a limb lead QRS vector of -600 to -1500. Reversible inferior defects demonstrated ectopic activity with LB85 and a superior axis. Ectopics of septal origin could present with either right or left 555 and an inferior axis from the upper septum or superior axis from the lower septum. Thus in this series analysis of ventricular ectopics rhythms in otherwise negative exercise ECG's was useful. The appearance of the ectopic in all 12 leads can localise its site of origin and this having been ascertained it may be correlated with the area of ischaemia giving valuable information about presence of disease in the supplying coronary artery.

COMPARATIVE ABILITY ELECTROCARDIOGRAPHY

OF UPRIGHT AND SUPINE BICYCLE EXERCISE TO DETECT CORONARY ARTERY DISEASE

Michael Levey, MD; Alan Rozanski, MD; Ricardo Valovis, MD; Deborah Ford; Denise Morris, BS; Nancy Pantaleo, RN, MS; Jamshid Maddahi, MD; H.J.C. Swan, MD, PhD, FACC; Daniel Berman, MD, FACC; Cedars-Sinai Med. Ctr., Los Angeles, CA

Left ventricular volume and wall tension differ durino the performance of upright and supine bicycle exercise. Since the electrocardioqraphic (ECG) manifestations of ischemia may be significantly'influenced by such factors, we sought to compare EX ECG in 31 patients undergoing both upright and then supine graded bicycle EX beginning at 200 kilo- ponds-meters/minute (kpm) and increasing by 200 kpms every three minutes of exercise. Abnormal ST response was de- fined as zlmn horizontal or downsloping depression and ab- normal R wave response as EX R wave amplitude> rest. In- cidence of angina and EX capacities were also compared. Results: Abnormal Response ST 13/31 42%)

Upright Supi;e 5/31 16%)

R Wave 6/31 (19%) 7/31 (22%) ST or R Wave 16/31 (52%) 11/31 (35%) Anaina Du;ation of EX

5/31 (16%) 8.8 min ’

5/31 (16%) 10.5 min

HR (maximum) 120.6 5PM 129.5 5PM BP (maximum) 176.5 mm Hg 186.0 mm Hg CONCLUSIONS: 1) Incidence of abnormal ST response with EX is much greater in the supine than upright position de- spite greater duration of exercise and higher HR and BP achieved with upright.EX. 2) Abnormal R wave changes and the incidence of exercise-induced angina are similar in both positions, despite the known differences in relative volume changes with upright versus supine EX.

MECHANISMS OF EXERCISE-INDUCED SUSTAINED VENTRICULAR TACHYCARDIA Ruey J. Sung, MD, FACC; Edward N. Shen, MD, Fred Morady. MD; Melvin M. Scheinmsn. MD, FACC; David Hess, MD, Moffi Hospital, University of California, San Francisco, CA

To delineate mechanisms underlying exercise-induced ven- tricular tachycardia (VT), 9 patients (pts), 7 men and 2 women, with recurrent VT associated wlth exertion, were evaluated. All pts were symptomatic of dizziness and/or syncope; 3 of them manifested aborted sudden death. Their ages. ranged from 28 to 58 (mean 42.5) years. 5 pts had arteriosclerotic heart disease with prior mvocardial in- farction, 2 pts cardlonlyopathy and 2'pts no-apparent heart disease. Using the Bruce's protocol for treadmill exercise testing, all pts developed sustained VT (lasting for 30 seconds or longer): 7 pts between stages II and V, and 2 pts during the recovery phase. All pts subsequently under- went electrophysiologic studies (EPS). Durfng EPS, all 9 pts had inducible sustaIned VT with QRS morphology iden- tical to that observed during treadmill exercise testing. In 6 its the mechanism of VT-appeared to be reentw as it could'be reproducibly elicitedwith ventricular extra- stimuli (YES) and terminated with overdrfve ventricular padng (OVP); In the remaining 3 pts, the mechanism of VT was presumd to be enhanced automaticity as It occurred spontaneouslv durino intravenous fnfusion of isooroterenol (4-6 ug/min)- it could nelther be elidted with VES nor could it be terminated with OVP. Based on these findings, we conclude that sustained VT induced wlth exercise can be due to efther reentry or enhanced automaticity. EPS is of use in deflnfng the underlying mechanism thereby pro- viding therapeutic guidance.

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March 1992 The American Journal ol CARDIOLOGY Volume 49 945