Design and analysis of the ESVEM Trial.

Inadequate understanding of the design and statistical approach of a clinical trial and the failure to recognize subjective aspects of the analysis often result in misinterpretation of trial results. This is exacerbated by the push to shorten publications and the wish for a simple message that summarizes the outcome of the trial. The purpose of this review is to critically review the design and statistical analyses of the results, to evaluate the assumptions underlying the statistical tests, and to examine the results of exploratory analysis on the interpretation of major findings of the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial. The trial was unusual because its primary objective was to compare testing methods instead of treatments. This necessitated using a subset of the original randomized groups for sensible analysis of the clinical question. Nevertheless, the two groups appeared to be well balanced. The absence of a difference in outcome could be verified by several analyses. In addition, confidence intervals were narrow, indicating the high precision and reliability of the findings. However, the comparison of antiarrhythmic drugs is problematic because the trial was not designed to address this issue. There were differences in the distribution of clinical characteristics between the groups who received different antiarrhythmic drugs. Nevertheless, using both univariate analyses and a variety of adjustments for important prognostic variables, treatment with sotalol appeared to be a significant predictor of reduced arrhythmia recurrence, and sotalol was consistently associated with a trend for nearly a 50% reduction in sudden death and all-cause mortality as compared with the other drugs administered in the trial. In conclusion, the ESVEM trial raises a number of interesting and instructive issues about clinical trial design and analysis.

Clinical significance of syncope in the electrophysiologic study versus electrocardiographic monitoring (ESVEM) trial. The ESVEM Investigators.

BACKGROUND: Syncope may portend risk of death, but which patients with syncope are at high risk remains unclear. OBJECTIVE: The ESVEM trial, a multicenter randomized prospective trial, provided the opportunity to compare mortality rates of patients enrolled with syncope to those enrolled with spontaneous ventricular arrhythmias. METHODS: Patients enrolled in the ESVEM trial presenting with syncope alone (25 patients) or in combination with ventricular tachycardia (24 patients) were compared with patients with spontaneous ventricular tachycardia alone (332 patients) or ventricular fibrillation (105 patients). All patients had ventricular tachyarrhythmias induced at electrophysiology testing of >/=10 premature ventricular complexes per hour on Holter monitor. RESULTS: Of all patients randomly assigned, arrhythmic death and total mortality rates were the same for those with syncope alone, with ventricular tachycardia and syncope, with ventricular tachycardia alone, or with ventricular fibrillation. At 1 year, arrhythmic and total mortality rate for all patients was 21% and 24%, respectively; for patients with syncope alone, 30% and 29%, respectively (P = NS). At 4 years, arrhythmic death and total mortality rate for all patients was 33% and 42%, respectively; for patients with syncope alone, 37% and 42%, respectively (P = NS). CONCLUSION: Syncope, associated with induced ventricular tachyarrhythmias at electrophysiologic testing, indicates high risk for death, similar to that of patients with documented spontaneous ventricular tachyarrhythmias.

Cost of initial therapy in the Electrophysiological Study Versus ECG Monitoring trial (ESVEM).

BACKGROUND: Patients randomized to either serial electrophysiological testing (EPS) or serial Holter monitoring (HM) to guide antiarrhythmic therapy for life-threatening ventricular arrhythmias had equivalent rates of mortality and arrhythmia recurrence in the ESVEM study. This report analyzes the effects of EPS, HM, and clinical factors on the charges for initial evaluation and management of patients with life-threatening ventricular arrhythmias. METHODS AND RESULTS: Ten of 14 clinical centers participating in ESVEM provided bills from the initial hospitalization for randomized patients. Predictors of charges (1991 dollars) were analyzed by linear regression after logarithmic transformation. Initial hospital charge data were obtained for 286 patients randomized in ESVEM (88% of patients eligible for this substudy, 59% of all ESVEM patients). Patients with charge data were somewhat more likely to be older, to be female, and to have failed previous antiarrhythmic drug therapy at study entry and were less likely to have a drug predicted effective after randomization. Mean overall hospital charges were $35,986 (SD, $32,628) with a median of $24,532 (interquartile range, $16,126 to $43,593). Prerandomization patient characteristics generally had insignificant effects on charges, with the exception of presentation with resuscitated sudden death (28% increase in charges, P = .01) and heart failure (26% increase in charges, P = .02). Patients randomized to EPS had higher mean charges for evaluation ($42,002 versus $29,970, P = .0015) as well as more drug trials (3.0 versus 2.1, P = .0001) and a longer hospital stay (19.6 versus 13.9 days, P = .0007). In a multivariate regression model, failure to find an effective drug (P = .0001), the number of drug trials (P = .0001), and resuscitated sudden death as the presenting arrhythmia (P = .0001) were the only independent predictors of higher initial charges. CONCLUSIONS: (1) Initial hospital charges are significantly higher for EPS-guided than HM-guided therapy. (2) The higher charges for EPS-guided therapy were due to a greater number of drug trials and a lower probability of finding an effective drug. (3) Failure to find an effective drug, a larger number of drug trials, and a history of resuscitated sudden death independently predict higher charges.

Predictors of arrhythmic death and cardiac arrest in the ESVEM trial. Electrophysiologic Study Versus Electromagnetic Monitoring.

BACKGROUND: The purpose of this study was to determine if the presenting ventricular arrhythmia (ventricular tachycardia or ventricular fibrillation/cardiac arrest) predicted the type of arrhythmia recurrence in patients treated with antiarrhythmic drugs. METHODS AND RESULTS: In the previously reported Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial, there were 486 patients who were randomized to antiarrhythmic drug testing guided by electrophysiological study or by ambulatory ECG monitoring. Use of a defibrillator (implantable cardioverter-defibrillator, ICD) without stored electrograms among 81 patients precluded determination of the type of arrhythmia recurrence; thus these patients were censored at the time of ICD implantation. Of the 486 patients, 381 presented with ventricular tachycardia and 105 with cardiac arrest. Over a 6-year follow-up period, 285 of the 486 patients had an arrhythmia recurrence; of these, 97 had an arrhythmic death or cardiac arrest as a first recurrence. In the current analysis, all 129 arrhythmic deaths/cardiac arrests that occurred any time during follow-up were evaluated as end points. CONCLUSIONS: Although univariate analysis suggested that there was an association between the presenting arrhythmia and outcome, multivariate analysis failed to substantiate the predictive value of the presenting arrhythmia. Left ventricular ejection fraction was the single most important predictor of arrhythmic death or cardiac arrest. This information may be an important factor in deciding whether to advise ICD therapy.

Ventricular remodeling in active myocarditis. Myocarditis Treatment Trial.

BACKGROUND: Remodeling of the left ventricle with the development of a spherical cavity occurs in dilated cardiomyopathy and is associated with a poor long-term prognosis. The early effects of myocarditis on left ventricular geometry have not been previously described or correlated with clinical outcome. METHODS: The baseline echocardiograms of 35 patients with biopsy-confirmed myocarditis were compared with 20 normal controls. Left ventricular end-diastolic volume, long axis length, and mid-cavity diameter were measured. The degree of sphericity was expressed as the ratio of the mid-cavity diameter to the long axis length. Left ventricular ejection fraction was assessed by radionuclide angiography. RESULTS: In patients with myocarditis, mean left ventricular volume of 81 +/- 29 mL/m(2) was significantly greater than 50 +/- 8 mL/m(2) in controls (P =.001). Chamber dilatation occurred primarily along the mid-cavity diameter, which measured 5.3 +/- 0.8 cm in patients with myocarditis versus 4.2 +/- 0.4 cm in controls (P =.001). The degree of left ventricular sphericity in patients with myocarditis, 0.64 +/- 0.08, was significantly greater than that of controls, 0.54 +/- 0.04 (P =.001). When patients were stratified according to left ventricular volume, patients with increased left ventricular volume (>75 mL/m(2)) were associated with a more spherical chamber and lower left ventricular ejection fraction than patients with a more normal left ventricular volume (

The Myocarditis Treatment Trial: design, methods and patients enrollment.

The Myocarditis Treatment Trial was a multicentre clinical trial conducted to determine the efficacy of immunosuppressive therapy for treatment of biopsy-documented myocarditis, and to improve understanding of the immunological mechanisms in the development of myocarditis. Thirty-one centres screened 2305 patients with unexplained heart failure, and 2233 patients underwent an endomyocardial biopsy which provided adequate tissue for diagnosis. Those with a positive biopsy and a left ventricular ejection fraction (LVEF) less than 45% were randomly assigned to receive immunosuppressive therapy plus conventional drug therapy for congestive heart failure (66 patients) or conventional therapy only (45 patients) for 24 weeks. For 28 additional weeks all patients received conventional therapy only. In addition to diagnostic and clinical data, serum and myocardial tissue for immunological marker analysis and histopathologic evaluation were collected at baseline and at 12, 28 and 52 weeks after randomization. The primary analysis of efficacy was designed as a comparison of the mean increase in LVEF at week 28 between treatment limbs. Secondary objectives were to evaluate survival differences, and changes in the histopathology of the disease and immunological markers. Randomized patients were relatively young (mean age, 42.0 years +/- 13.8 standard deviation (sd) and entered the Trial with a mean LVEF percent of 24.3 +/- 10.1 sd) and mean exercise treadmill duration of 9.4 (+/- 5.3 sd) minutes. The incidence of biopsy-documented myocarditis was low (9.6%). The analyses of outcome and immunological data are reported elsewhere.