CASE REPORT
Exercise-induced myocardial ischaemia complicated by paroxysmal complete atrioventricular block W - J H O , P - H C H U , N - J C H E N G , T - S H S U , Y - S L EE
The Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Taipei, Taiwan
SUMMARY
This study describes a case of exercise-induced myocardial ischaemia accompanied by complete atrioventricular block (CAVB). A 59-year-old man with major depression, treated with regular imipramine and lithium for 20 years, experienced syncope episodes during exercise. Exercise, testing initially, identified ST depression in the inferior leads, and later found CAVB resulting in syncope and seizure. The patient recovered completely after resuscitation. Myocardial ischaemic markers were negative, but
INTRODUCTION
Exercise-induced complete atrioventricular block (CAVB) in patients with normal resting electrocardiogram is rare (1–4). This study reports the clinical features of a 59-year-old male with recurrent syncope on exercise, caused by CAVB without conduction system abnormalities at rest. To our knowledge, this study is the first to describe a case of exercise-induced myocardial ischaemia resulting in paroxysmal CAVB as the initial presentation in a 59-year-old male.
CASE REPORT
A 59-year-old male presented to our out-patient department, complaining of syncope that lasted for 5 min after exercise in the morning, on June 17, 2003. The man regularly took imipramine (112 mg per day) and lithium carbonate (600 mg per night) for major depression. Clinical examination was unremarkable. Resting ECG revealed sinus rhythm. The patient underwent a treadmill test immediately after presenting at our clinic. After 3 min of performing the stage 1 exercise test, the patient complained of chest discomfort with ST elevation in the inferior leads and V2 (Figure 1). The patient then suddenly collapsed and suffered a CAVB-
Correspondence to: Pao-Hsien Chu, MD, The First Cardiovascular Division, Chang Gung Memorial Hospital, School of Medicine, Chang Gung University, 199 Tun-Hwa North Road, Taipei 105, Taiwan Tel.: 1886-3-328-1200x8162 Fax: 1886-3-327-1192 Email:
[email protected]
35% stenosis was detected in the distal left main coronary artery by angiography. The combined use of verapamil, nitrate and aspirin was treated as the possible coronary spasm. Repeat treadmill caused negative ischaemic study or exercise-induced arrhythmia, 7 days later. The pathophysiology of the very rare exercise-induced paroxysmal CAVB has been reviewed. Keywords: Complete atrioventricular block; myocardial ischaemia 2005 Blackwell Publishing Ltd
induced seizure (Figure 2A). Subsequently taken ECG displayed persistently elevated ST in the inferior leads and V1 with reciprocal ST depression in V2 to V6 (Figure 2B). Following 4-min emergent resuscitation, the patient recovered completely except for persisting sinus tachycardia (Figure 3). Sequential cardiac troponin-I and creatine kinase MB were normal. Other test results included elevated uric acid (12.4 mg/dl, normal range: 2.5–7.5 mg/dl) and cholesterol (219 mg/dl, normal limit: below 200 mg/dl). Blood levels of imipramine and lithium carbonate were both within normal limits. Chest X-ray, echocardiography and brain computer tomograph were all unremarkable. 1 h later, emergent coronary angiography indicated 35% stenosis in the distal left main coronary artery with TIMI 4 flow, and no obvious thrombus was demonstrated. However, the patient refused to perform ergonovine provocation for coronary artery or electrophysiological studies. Under the impression of coronary spasm, the patient was treated daily with aspirin (100 mg), verapamil SR (240 mg), isosorbide-5-mononitrate CR (60 mg) and atorvastatin (10 mg). Repeat treadmill test after 7 days of therapy was negative for myocardial ischaemia or exercise-related arrhythmia. The patient was discharged symptom-free, on June 24. The follow-up period was free of syncope or chest pain events occurring simultaneously with lithium and venlafaxine ER (75 mg) for major depression.
DISCUSSION
Exercise-induced atrioventricular block is rare and mostly involves the distal atrioventricular block and second degree block (5–13). This study reviewed the pathophysology of a
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Figure 1 After 3 min of stage 1 exercise test, the ECG reveals tachycardia and infernal wall ischaemia, ST elevation II, III, avF and V1 leads
59-year-old male with serious depression, who experienced CAVB resulting from documented myocardial ischaemia during exercise. First, the subject patient had undergone regular treatment for depression involving imipramine, a tricyclic anti-depressant (TCA), and lithium carbonate. A growing body of evidence exists that depression significantly and adversely impacts cardiovascular health (14). Regarding safety, the TCAs, such as imipramine, and lithium carbonate have documented adverse cardiovascular effects, including increase in heart rate, orthostatic hypotension and conduction delays that prolong PR interval (15,16), but not including the myocardial ischaemia or CAVB noted in this patient. However,
ECGs still are indicated whenever the history or physical findings suggest cardiovascular disease or whenever it is proposed that psychiatric patients be treated with psychotherapeutic drugs known to increase cardiac conduction times or otherwise alter cardiac function. Second, the subject patient may be a case of microvascular angina accompanied by coronary artery spasm despite the absence of documented intracoronary ergonovine or acetylcholine-provoked coronary spasm. Several investigations exist that relate to the exercise-related atrioventricular block with evidence of vasospasm or transient ischaemia of the conduction system (17–21). Usually, the vasospasm can be demonstrated by ergonovine provocation test (22,23) and treated by
Figure 2 ECG demonstrates complete atrioventricular block (A). Persisting elevated ST segments are demonstrated in leads II, III, avF and V1 with reciprocal ST-T depression in leads I, avL, V2 to V6 and complete atrioventricular block (B) ª 2005 Blackwell Publishing Ltd Int J Clin Pract, April 2005, 59 (Suppl. 147), 19–22
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Figure 3 After 4-min resuscitation, the ECG revealed sinus tachycardia without obvious myocardial ischaemia or infarction
nitrate and/or calcium channel blockage for vasodilation, as in the present case. To our knowledge, exercise-induced CAVB has only been described previously in one patient with chronic bifascicular block (4) and another asymptomatic athlete (3). The patient described here, thus, appears to be the first documented case of exercise-triggered myocardial ischaemia resulting in CAVB. CONCLUSION
The case presented here and the literature review indicate that exercise-induced myocardial ischaemia followed by transient CAVB may completely resolve if treated as coronary artery disease. ACKNOWLEDGEMENTS
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Paper received February 2004, accepted March 2004
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