Life-threatening ventricular arrhythmias in patients with silent myocardial ischemia due to coronary-artery spasm

Prospective study of phobic anxiety and risk of coronary heart disease in men

BACKGROUND

To examine prospectively the association between self-reported symptoms of phobic anxiety and subsequent risk of coronary heart disease, a 2-year follow-up study was conducted of a cohort of 33,999 US male health professionals, aged 42 to 77 years in 1988, who were free of diagnosed cardiovascular disease at baseline. Levels of phobic anxiety were assessed using the Crown-Crisp index, a short, diagnostic self-rating scale used for common phobias. Main outcomes were incidents of coronary heart disease consisting of nonfatal myocardial infarction (MI) and fatal coronary heart disease (CHD).

METHODS AND RESULTS

One hundred sixty-eight incident cases of CHD occurred during 2 years of follow-up (128 cases of nonfatal MI and 40 cases of fatal CHD). The age-adjusted relative risk of fatal CHD among men with highest levels of phobic anxiety (scoring 4 or higher on the Crown-Crisp index) was 3.01 (95% confidence interval, 1.31 to 6.90) compared with men with the lowest levels of anxiety (scoring 0 or 1 on the phobia index). Risk of fatal CHD increased with levels of phobic anxiety (P trend = .002). When fatal CHD was further categorized into sudden and nonsudden coronary death, the excess risk was confined to sudden death (relative risk among men scoring 3 or higher on the phobia index was 6.08; 95% confidence interval, 2.35 to 15.73). No association was found between phobic anxiety and risk of nonfatal MI. These findings remained essentially unchanged after adjusting for a broad range of cardiovascular risk factors.

CONCLUSIONS

The specificity, strength, and dose-response gradient of the association, together with the consistency and biological plausibility of the experimental and epidemiologic evidence, support a strong causal association between phobic anxiety and fatal CHD.

Autologous blood donation before myocardial revascularization: a Holter-electrocardiographic analysis

The influence of preoperative autologous blood donation on myocardial ischemia and arrhythmias was evaluated in 24 patients scheduled for coronary artery bypass grafting (CABG). All had a Holter recorder placed 24 hours before predonation (day 1), the cassette was changed prior to donation, and the recording continued for 24 hours thereafter (day 2). Each patient served as his or her own control, and observations made on day 2 were compared with those of day 1. Ischemia was quantitated by calculating the duration (C.Dur.) and the area (C. Area) of ischemic ST segment depressions, and ventricular premature beats (VPB) were classified according to the Lown grading system. Twenty-one men and 3 women were monitored. On day 1, 9 patients had 20 ischemic events, 3 being symptomatic. Nine patients demonstrated ischemia on day 2, representing a total of 3 symptomatic and 26 silent events. When comparing the two monitoring periods, 7 patients had longer or more severe ST segment depression whereas 6 other patients presented with more severe VPBs on day 2. Three patients had less ischemia on day 2, one remained stable, and 13 had no ischemia throughout the study. Silent ischemia was significantly more prolonged (C.Dur.Sil 316 v 152 sec, P < 0.05) and more intense (C. Area Sil 8 v 3.8 mm.min, P < 0.05) on day 2. Moreover, on top of a normal circadian distribution of ischemic events in the morning and in the evening, 40% of events were related to the donation or to a trip to the hospital. No preoperative characteristic helped to detect patients at risk.(ABSTRACT TRUNCATED AT 250 WORDS)

Vasospastic angina without flow-limiting coronary lesions as a cause for aborted sudden death

Two patients resuscitated from out-of-hospital cardiac arrest were later found to have minor coronary atherosclerosis and no inducible ventricular arrhythmia. Coronary spasm was not elicited during provocative tests but occurred on introduction of the catheter in the right coronary artery and spontaneously recurred after resuscitation, leading to myocardial infarction in one patient. Both patients received an implantable cardioverter defibrillator and subsequent discharges, while receiving calcium antagonists.

Importance of thrombosis and thrombolysis in silent ischaemia: comparison of patients with acute myocardial infarction and unstable angina

OBJECTIVE

To investigate whether plaque rupture and thrombosis have a role in silent ischaemia as well as in unstable angina.

DESIGN

Prospective analysis of the results of haemostatic diagnostic tests at the moment of developing silent ischaemia at rest.

SETTING

Coronary care unit.

PATIENTS

22 patients with acute myocardial infarction, 12 patients with symptomatic angina (unstable angina), and 10 normal volunteers (control group).

INTERVENTIONS

Continuous cardiac monitoring detected 15 asymptomatic episodes (silent ischaemia) in 6 patients with unstable angina. Blood samples were obtained at admission and when an asymptomatic alteration was detected and 10 minutes later.

MAIN OUTCOME MEASURES

Comparisons of concentrations of tissue plasminogen activator, urokinase type plasminogen activator, tissue plasminogen activator inhibitor-1, cross-linked fibrin degradation products, von Willebrand factor, and thrombin-antithrombin III complexes in patients and controls at admission; same comparisons in patients with silent ischaemia at the start of an episode and 10 minutes later.

RESULTS

Tissue plasminogen activator concentrations were raised at admission in patients with acute myocardial infarction (mean (SD) 14.2 (6) ng/ml) and in patients with unstable angina (10.1 (2.5) ng/ml) in comparison with controls (5.1 (2.7) ng/ml, p < 0.01 and < 0.05 respectively). There was no differences between the two groups of patients, however. Similar results were observed at the start of a silent ischaemic episode (9.8 (1.9) ng/ml) and 10 minutes later (10.5 (2.9) ng/ml) compared with controls (p < 0.05). Tissue plasminogen activator inhibitor-1 concentrations were raised in patients with acute myocardial infarction (45.1 (15) ng/ml) compared with volunteers (20.6 (16) ng/ml, p < 0.01). In patients with silent ischaemia tissue plasminogen activator inhibitor-1 concentrations were slightly but not significantly increased. Concentrations of cross-linked fibrin degradation products (D dimer) increased during unstable angina (2150 (350) ng/ml) and silent ischaemia (2270 (450) ng/ml) compared with the concentrations in volunteers (340 (80) ng/ml) and patients with acute myocardial infarction (310 (120) ng/ml; p < 0.01).

CONCLUSIONS

The results suggest that thrombosis mediates the pathophysiological mechanisms of silent ischaemia and unstable angina.

Ventricular fibrillation in a patient with exercise-induced anaphylaxis, normal coronary arteries, and a positive ergonovine test

Exercise-induced anaphylaxis (EIA) is a rare form of physical allergy. Although histamine release is a feature of EIA, and histamine provocation of coronary spasm has been described, serious cardiac arrhythmias in EIA have not been reported. Exercise-induced anaphylaxis was diagnosed in a survivor of out-of-hospital cardiac arrest due to ventricular fibrillation after ECG signs of coronary spasm. Coronary artery disease was excluded. Ergonovine provocation induced coronary spasm in this patient. This is, to the authors' knowledge, the first description of ventricular fibrillation in EIA, possibly due to coronary spasm.

ST-segment instability preceding simultaneous cardiac arrest and AMI in a patient undergoing continuous 12-lead ECG monitoring

Little data exist concerning the actual onset time (time zero) in sudden death (SD) and acute myocardial infarction (AMI). Most studies have focused on describing the warning arrhythmias that occur before SD and AMI and have relied on retrospective analyses of fortuitous data obtained from patients who experience these adverse outcomes while undergoing routine ambulatory holter monitoring. Because of the limitations of holter monitoring, little information is known concerning the actual incidence of ST-segment changes preceding SD and AMI. The first case of simultaneous onset of silent SD and AMI occurring in a patient undergoing continuous 12-lead electrocardiograph (ECG) monitoring during his initial emergency department evaluation is reported. Analyses of the serial 12-lead electrocardiographs showed extensive transient silent ST-segment elevations and depressions preceding cardiac arrest and AMI and provided insight in the pathogenesis of SD and AMI. Continuous 12-lead ECG monitoring can identify patients at high risk for SD and AMI and allow physicians to intervene before the development of life-threatening conditions.

Unfavorable outcome in patients with primary electrical disease who survived an episode of ventricular fibrillation

BACKGROUND

Prognosis in patients with ventricular tachyarrhythmia without structural heart disease (primary electrical disease) has been described as excellent. However, prognosis may be less favourable in the subgroup surviving an episode of ventricular fibrillation.

METHODS AND RESULTS

We prospectively followed 19 consecutive patients (age, 13 to 66 years; mean age, 33 years) who had survived an episode of documented ventricular fibrillation. Structural heart disease, preexcitation, and long QT syndromes were excluded by thorough cardiologic evaluation. All patients underwent 24-hour Holter monitoring, exercise testing, and programmed electrical stimulation according to a standardized protocol. Holter monitoring revealed episodes of ventricular tachyarrhythmia in 5 patients. Exercise testing reproducibly provoked ventricular tachycardia in 2 patients. Baseline programmed electrical stimulation yielded inducibility of rapid ventricular tachyarrhythmia in 10 patients (53%) and noninducibility in 9 (47%). Nine patients were discharged on antiarrhythmic drug therapy. A defibrillator was implanted in 10 patients. During 43-month follow-up (range, 5 to 85 months; median, 41 months), major arrhythmic events recurred in 7 patients (37%). Four of these patients had noninducibility at baseline programmed electrical stimulation. Two patients on antiarrhythmic drugs had recurrent cardiac arrest: one died suddenly and the other was successfully resuscitated from ventricular fibrillation and subsequently underwent defibrillator implantation. In the other 5 patients, termination of (pre)syncopal episodes was associated with defibrillator shocks. Termination of ventricular fibrillation was documented by Holter recording in one of these patients. Specific markers predictive of a recurrent event could not be identified, although 6 of 7 patients with recurrent events had experienced at least one episode of cardiac arrest or (pre)syncope before the index episode.

CONCLUSIONS

Patients with primary electrical disease presenting with ventricular fibrillation are at high risk of recurrence of major arrhythmic events during long-term follow-up. Noninducibility at baseline study does not predict an uneventful course. Also, early defibrillator implantation should be considered in these patients.

Ventricular fibrillation in patients without significant structural heart disease: a multicenter experience with implantable cardioverter-defibrillator therapy

OBJECTIVES

This study was undertaken to characterize the outcome of survivors of ventricular fibrillation with no or minimal structural heart disease who received an implantable cardioverter-defibrillator.

BACKGROUND

The prognosis among survivors of ventricular fibrillation with minimal or no structural cardiac abnormalities remains unclear. Since the advent of implantable cardioverter-defibrillators, this question takes on added importance.

METHODS

This 10-center retrospective study provided information on 28 survivors of ventricular fibrillation (mean age 42 years) with minimal or no structural abnormalities who were treated with an implantable cardioverter-defibrillator.

RESULTS

Ventricular tachyarrhythmias (polymorphic in all but one patient) were induced during baseline programmed stimulation in 39% of patients. During a median 30.6-month follow-up period after implantable cardioverter-defibrillator implantation, there were no cardiac deaths and two noncardiac deaths. Sixteen patients experienced 36 shock episodes (total 88 shocks). The majority of shocks were classified as "indeterminate"; one patient received 47 "spurious" shocks during one shock episode and each of four patients received one "appropriate" shock. Ventricular arrhythmias were not inducible in any of these latter four patients.

CONCLUSIONS

Survivors of ventricular fibrillation with minimal or no structural cardiac abnormalities receiving an implantable cardioverter-defibrillator have an excellent 3-year survival rate. The occurrence, albeit infrequent, of appropriate implantable cardioverter-defibrillator shocks in this group suggests that these patients have a potential risk of recurrent cardiac arrest whose fatal outcome may be avoided by implantable cardioverter-defibrillator therapy.

The ionic mechanism of reperfusion-induced early afterdepolarizations in feline left ventricular hypertrophy

Left ventricular hypertrophy (LVH) potentiates reperfusion-associated ventricular fibrillation. To study the mechanism responsible, patch-clamp techniques were used to evaluate transmembrane ionic currents during "reperfusion" after a CN(-)-induced metabolic surrogate for ischemia in isolated myocytes from a feline model of experimental LVH. Reperfusion caused the generation of early afterdepolarizations (EADs) from an average take-off potential of -33 mV in LVH cells but not in cells from normal hearts. 10 min after initiating reperfusion of normal cells, action potential duration (APD) at 50% repolarization (APD50) lengthened from 198 +/- 41 to 233 +/- 57 ms whereas in LVH cells APD50 lengthened from 262 +/- 84 to 349 +/- 131 ms (P < 0.05). Among the LVH cells, APD50 lengthening was significantly greater in the cells that had developed EADs. During reperfusion, steady state outward current in the voltage range of the action potential plateau (between -20 and +20 mV) was reduced from the control values in LVH cells but not in normal cells. Reperfusion-related reduction of steady state outward current in LVH cells was abolished under experimental conditions in which L-type Ca2+ current was isolated from other classes of currents whereas it was still observed under the condition in which pure K+ currents could be recorded. Thus, reduction of steady state outward current due to the reduction of outward K+ current over the action potential plateau voltage range appears to be responsible for an excessive prolongation of APD, leading to the development of EADs.

Cardiac arrest and sudden unexpected death in variant angina: complications of coronary spasm that can occur in the absence of severe organic coronary stenosis

Experiences in 81 patients with variant angina were reviewed with the goal of determining which clinical features were associated with the greatest risk of angina-linked cardiac arrest (13 patients) or sudden unexpected death (9 patients). The risk of occurrence of one of these actually or potentially fatal events was approximately tripled by the presence of either a history of angina-linked syncope or documentation of serious arrhythmia complicating attacks. An unexpected finding was that the risk was increased 1.5-fold by the absence of high-grade organic coronary stenosis. Cardiac arrest and sudden death are important risks of variant angina, which can occur without the presence of severe organic coronary stenosis. These risks can be reduced by adequate vasodilator therapy that includes a calcium channel blocker.

Does reperfusion injury exist in humans?

Timely coronary reperfusion as treatment for acute myocardial infarction reduces myocardial infarct size, improves left ventricular function and survival. There is still concern that at the time of reperfusion, a further injury occurs to the myocardium. Theoretically, if this "reperfusion injury" could be treated and eliminated, the outcome for patients with myocardial infarction might further improve. The concept of reperfusion injury is closely tied to the concept that oxygen radicals generated at the time of reperfusion cause tissue damage. There are four basic forms of reperfusion injury. Lethal reperfusion injury is described as myocyte cell death due to reperfusion itself rather than to the preceding ischemia. This concept continues to be controversial in both experimental animal and clinical studies. Vascular reperfusion injury refers to progressive damage to the vasculature over time during the phase of reperfusion. Manifestations of vascular reperfusion injury include an expanding zone of no reflow and a deterioration of coronary flow reserve. This form of reperfusion injury has been documented in animal models and probably occurs in humans. Stunned myocardium refers to postischemic ventricular dysfunction of viable myocytes and probably represents a form of "functional reperfusion injury." This phenomenon is well documented in both animal models and humans. Reperfusion arrhythmias represent the fourth form of reperfusion injury. They include ventricular tachycardia and fibrillation that occur within seconds to minutes of restoration of coronary flow after brief (5 to 15 min) episodes of myocardial ischemia. True reperfusion arrhythmias occur in only a small percentage of patients receiving thrombolytic therapy for acute myocardial infarction and are not a sensitive indicator for successful reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Pre-hospital cardiac arrest associated with coronary artery spasm

A 37-yr-old woman with an 8-month history of chest pain, unrelated to exercise, was successfully resuscitated from out-of-hospital cardiac arrest due to ventricular fibrillation. Cardiac catheterisation revealed minor coronary artery disease. Ergometrine injection was associated with complete occlusion of the left anterior descending coronary associated with identical chest pain and pronounced ST-segment changes.