Cardiovascular complications of thrombolytic therapy in patients with a mistaken diagnosis of acute myocardial infarction.

Thrombolytic drugs given to patients with a mistaken diagnosis of acute myocardial infarction could produce adverse effects, although no such cases have been reported. Two patients treated with intravenous streptokinase for presumed but nonexistent acute myocardial infarction are described. Pericardial tamponade developed in both patients, in one after aortic dissection and in the other after pericarditis. Both required surgery; one died. Symptoms and electrocardiographic abnormalities mimicking acute myocardial infarction may be caused by non-coronary syndromes. In such cases, treatment with thrombolytic agents may exacerbate the underlying disease process and produce cardiovascular complications.

Percutaneous transluminal coronary angioplasty in the setting of large intracoronary thrombi.

A cohort of 112 consecutive patients with angiographically defined intracoronary thrombi was treated with percutaneous transluminal coronary angioplasty and followed prospectively to determine early and late outcomes. Coronary angioplasty using a treatment modality of intravenous and intracoronary heparin, antiplatelet agents and prolonged inflations with oversized balloons (balloon:vessel ratio, 1.2:1) resulted in clinical success in 103 patients (92%) at hospital discharge. No periprocedural thrombolytic therapy was used and prolonged pretreatment with heparin was not routinely used. Four patients (3.5%) required elective coronary bypass surgery, and 4 patients (3.5%) required emergency coronary artery bypass grafting because of abrupt closure. Late clinical follow-up (mean 7 months) was available in 99 of the 103 successfully treated patients (96%). Seventy-three percent of patients were asymptomatic at follow-up, and 27% had class I or II angina. No patients had a late myocardial infarction. Elective coronary artery bypass surgery was required in 3 patients (3%) and repeat coronary angioplasty in 17 patients (17%). There were 2 late cardiac deaths at 7 months. Ninety-four patients (95%) had an event free follow-up defined as absence of coronary artery bypass surgery, myocardial infarction or death. In conclusion, coronary angioplasty alone, using intracoronary heparin and prolonged balloon inflations with relatively oversized balloons may be helpful to achieve a high initial success rate, low incidence of in-hospital complications and excellent long-term results in patients with intracoronary thrombus.

Implantation of the implantable cardioverter defibrillator in the heart transplant candidate.

Because the major cause of death in patients awaiting heart transplantation results from out-of-hospital sudden cardiac arrest, the use of the implantable cardioverter defibrillator has been proposed as a bridge to transplantation. To provide a safe and simple implantation procedure that also easily allows access to cardiopulmonary bypass at the time of transplantation, a modified subxiphoid approach is reported.

Clinical course of hypertrophic cardiomyopathy in a regional United States cohort.

CONTEXT: Hypertrophic cardiomyopathy (HCM) has been regarded as a disease that causes substantial disability, with annual mortality rates of up to 6%, based largely on reports from tertiary referral centers. OBJECTIVE: To assess the clinical course of HCM in a patient cohort more closely resembling the true disease state. DESIGN: Retrospective cohort study. SETTING: A regional cohort from Minnesota and adjoining regions, free of referral center bias, studied at Minneapolis Heart Institute. PATIENTS: Two hundred seventy-seven consecutively studied HCM patients, none referred for specialized HCM care, managed clinically in a standard fashion. MAIN OUTCOME MEASURES: Mortality and clinical course of HCM. RESULTS: During a mean (SD) follow-up of 8.1 (6.6) years, 45 patients died and 29 of these deaths were directly related to HCM; however, 8 of the 29 HCM deaths were not premature (occurring >75 years of age). Annual HCM mortality rate was 1.3% (0.7% for sudden cardiac death). Patients identified in adulthood (n = 234) showed no statistically significant difference in mortality when compared with expected mortality, as calculated for the general US or Minnesota populations (P=.17). Patients identified as children (n=43) showed decreased survival compared with the general population (P<.001). At most recent clinical evaluation, 192 patients (69%) had no or mild symptoms and 69 (25%) experienced incapacitating symptoms or HCM-related death; 53 (19%) of the patients had achieved estimated life expectancy of 75 years or older. More advanced symptoms at diagnosis-occurrence of atrial fibrillation (often associated with stroke), the presence of basal outflow obstruction of at least 30 mm Hg, and marked left ventricular wall thickness of more than 25 mm-were clinically important independent predictors of HCM mortality. CONCLUSIONS: In a regionally selected patient population most closely resembling the true disease state, HCM did not significantly increase the risk of premature death or adversely affect overall life expectancy. Prevailing misconceptions of HCM as a generally unfavorable condition may largely be related to the skewed patient referral patterns characteristic of tertiary care centers. Hypertrophic cardiomyopathy is nevertheless a highly complex disease capable of serious clinical consequences and premature death in some patients.

Unexpected ICD pulse generator failure due to electronic circuit damage caused by electrical overstress.

Because it is a lifesaving device, the unexpected failure of an ICD can be catastrophic. We report ICD electronic circuit failure due to electrical overstress damage (EOS) to the high voltage hybird circuit and other electronic components in a series of ICD pulse generator models. Data were obtained from the Multicenter Registry of Pacemaker and ICD Pacemaker and Lead Failures, and from the manufactures' adverse event reports, that were in the FDA's Manufacturer and User Facility Device Experience (MAUDE) database. Of 16 nonbattery Guidant/CPI ICD pulse generator failures reported to the registry, 6 (38%) have been confirmed by the manufacturer to be EOS related, and Guidant/CPI has reported 273 such failures to the FDA as of 12/29/00. The signs of failure included loss of telemetry and inability to deliver therapy, and some patients have experienced serious adverse events. Hybrid circuit damage may have occurred during capacitor charging or reform, and the majority appears to have happened during normal ICD function. While the incidence of this problem is unknown, a management strategy should be adopted that includes routine follow-up every 3 months and device evaluation after a shock or exposure to external defibrillation or electrosurgical devices. This study suggests that additional data are needed to determine the incidence of this problem, and that our present methods for monitoring the performance of ICD's following market release are inadequate.

Efficacy of implantable cardioverter-defibrillators for the prevention of sudden death in patients with hypertrophic cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy is a genetic disease associated with a risk of ventricular tachyarrhythmias and sudden death, especially in young patients. METHODS: We conducted a retrospective multicenter study of the efficacy of implantable cardioverter-defibrillators in preventing sudden death in 128 patients with hypertrophic cardiomyopathy who were judged to be at high risk for sudden death. RESULTS: At the time of the implantation of the defibrillator, the patients were 8 to 82 years old (mean [+/-SD], 40+/-16), and 69 patients (54 percent) were less than 41 years old. The average follow-up period was 3.1 years. Defibrillators were activated appropriately in 29 patients (23 percent), by providing defibrillation shocks or antitachycardia pacing, with the restoration of sinus rhythm; the average age at the time of the intervention was 41 years. The rate of appropriate defibrillator discharge was 7 percent per year. A total of 32 patients (25 percent) had episodes of inappropriate discharges. In the group of 43 patients who received defibrillators for secondary prevention (after cardiac arrest or sustained ventricular tachycardia), the devices were activated appropriately in 19 patients (11 percent per year). Of 85 patients who had prophylactic implants because of risk factors (i.e., for primary prevention), 10 had appropriate interventions (5 percent per year). The interval between implantation and the first appropriate discharge was highly variable but was substantially prolonged (four to nine years) in six patients. In all 21 patients with stored electrographic data and appropriate interventions, the interventions were triggered by ventricular tachycardia or fibrillation. CONCLUSIONS: Ventricular tachycardia or fibrillation appears to be the principal mechanism of sudden death in patients with hypertrophic cardiomyopathy. In high-risk patients with hypertrophic cardiomyopathy, implantable defibrillators are highly effective in terminating such arrhythmias, indicating that these devices have a role in the primary and secondary prevention of sudden death.