Long-Term Effect of Endothelin Receptor Antagonism With Bosentan on the Morbidity and Mortality of Patients With Severe Chronic Heart Failure: Primary Results of the ENABLE Trials

OBJECTIVES

The objective of this clinical trial was to evaluate the long-term effect of endothelin receptor antagonism with bosentan on the morbidity and mortality of patients with severe chronic heart failure.

BACKGROUND

Endothelin may play a role in heart failure, but short-term clinical trials with endothelin receptor antagonists have reported disappointing results. Long-term trials are lacking.

METHODS

In 2 identical double-blind trials, we randomly assigned 1,613 patients with New York Heart Association functional class IIIb to IV heart failure and an ejection fraction <35% to receive placebo or bosentan (target dose 125 mg twice daily) for a median of 1.5 years. The primary outcome for each trial was clinical status at 9 months (assessed by the hierarchical clinical composite); the primary outcome across the 2 trials was death from any cause or hospitalization for heart failure.

RESULTS

Bosentan did not influence clinical status at 9 months in either trial (p = 0.928 and p = 0.263). In addition, 321 patients in the placebo group and 312 patients in the bosentan group died or were hospitalized for heart failure (hazard ratio [HR]: 1.01; 95% confidence interval [CI]: 0.86 to 1.18; p = 0.90). The bosentan group experienced fluid retention within the first 2 to 4 weeks, as evidenced by increased peripheral edema, weight gain, decreases in hemoglobin, and an increased risk of hospitalization for heart failure, despite intensification of background diuretics. During follow-up, 173 patients died in the placebo group and 160 patients died in the bosentan group (HR: 0.94; 95% CI: 0.75 to 1.16). About 10% of the bosentan group showed meaningful increases in hepatic transaminases, but none had acute or chronic liver failure.

CONCLUSIONS

Bosentan did not improve the clinical course or natural history of patients with severe chronic heart failure and but caused early and important fluid retention.

Case report: Severe hypercalcemia mimicking ST-segment elevation myocardial infarction

The identification of ST-segment elevation on the electrocardiogram is an integral part of decision making in patients who present with suspected ischemia. Unfortunately, ST-segment elevation is nonspecific and may be caused by noncardiac causes such as electrolyte abnormalities. We present a case of ST-segment elevation secondary to hypercalcemia in a patient with metastatic cancer.

Efficacy and safety of prescription omega-3 fatty acids for the prevention of recurrent symptomatic atrial fibrillation: a randomized controlled trial

CONTEXT

Atrial fibrillation (AF) is common, yet there remains an unmet medical need for additional treatment options. Current pharmacological treatments have limited efficacy and significant adverse events. Limited data from small trials suggest omega-3 polyunsaturated fatty acids may provide a safe, effective treatment option for AF patients.

OBJECTIVE

To evaluate the safety and efficacy of prescription omega-3 fatty acids (prescription omega-3) for the prevention of recurrent symptomatic AF.

DESIGN, SETTING, AND PARTICIPANTS

Prospective, randomized, double-blind, placebo-controlled, parallel-group multicenter trial involving 663 US outpatient participants with confirmed symptomatic paroxysmal (n = 542) or persistent (n = 121) AF, with no substantial structural heart disease, and in normal sinus rhythm at baseline were recruited from November 2006 to July 2009 (final follow-up was January 2010).

INTERVENTIONS

Prescription omega-3 (8 g/d) or placebo for the first 7 days; prescription omega-3 (4 g/d) or placebo thereafter through week 24.

MAIN OUTCOME MEASURES

The primary end point was symptomatic recurrence of AF (first recurrence) in participants with paroxysmal AF. Secondary analyses included first recurrence in the persistent stratum and both strata combined. Participants were followed up for 6 months.

RESULTS

At 24 weeks, in the paroxysmal AF stratum, 129 of 269 participants (48%) in the placebo group and 135 of 258 participants (52%) in the prescription group had a recurrent symptomatic AF or flutter event. In the persistent AF stratum, 18 participants (33%) in the placebo group and 32 (50%) in the prescription group had documented symptomatic AF or flutter events. There was no difference between treatment groups for recurrence of symptomatic AF in the paroxysmal stratum (hazard ratio [HR], 1.15; 95% confidence interval [CI], 0.90-1.46; P = .26), in the persistent stratum (HR, 1.64; 95% CI, 0.92-2.92; P = .09), and both strata combined (HR, 1.22; 95% CI, 0.98-1.52; P = .08). Other, secondary end points were supportive of the primary result. A total of 5% of those receiving placebo and 4% of those receiving prescription omega-3 discontinued due to adverse events. Eicosapentaenoic and docosahexaenoic acid blood levels were significantly higher in the prescription group than in the placebo group at weeks 4 and 24.

CONCLUSION

Among participants with paroxysmal AF, 24-week treatment with prescription omega-3 compared with placebo did not reduce recurrent AF over 6 months.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00402363.

Usefulness of vernakalant hydrochloride injection for rapid conversion of atrial fibrillation

The objective of the present study was to assess the safety and effectiveness of vernakalant hydrochloride injection (RSD1235), a novel antiarrhythmic drug, for the conversion of atrial fibrillation (AF) or atrial flutter to sinus rhythm (SR). Patients with either AF or atrial flutter were randomized in a 1:1 ratio to receive vernakalant (n = 138) or placebo (n = 138) and were stratified by an arrhythmia duration of >3 hours to ≤7 days (short duration) and 8 to ≤45 days (long duration). The first infusion of placebo or vernakalant (3 mg/kg) was given for 10 minutes followed by a second infusion of placebo or vernakalant (2 mg/kg) 15 minutes later if the arrhythmia had not terminated. A total of 265 patients were randomized and received treatment. The primary end point was conversion of AF to SR for ≥1 minute within 90 minutes of the start of the drug infusion in the short-duration AF group. Of the 86 patients receiving vernakalant in the short-duration AF group, 44 (51.2%) demonstrated conversion to SR compared to 3 (3.6%) of the 84 in the placebo group (p <0.0001). The median interval to conversion of short-duration AF to SR in the responders given vernakalant was 8 minutes. Of the entire AF population (short- and long-duration AF), 47 (39.8%) of the 118 vernakalant patients experienced conversion of AF to SR compared to 4 (3.3%) of the 121 placebo patients (p <0.0001). Transient dysgeusia and sneezing were the most common adverse events in the vernakalant patients. One vernakalant patient who had severe aortic stenosis experienced hypotension and ventricular fibrillation and died. In conclusion, vernakalant demonstrated a rapid and high rate of conversion for short-duration AF and was well tolerated.

Practice patterns among United States cardiologists for managing adults with atrial fibrillation (from the AFFECTS Registry)

The Atrial Fibrillation: Focus on Effective Clinical Treatment Strategies (AFFECTS) Registry was designed to examine atrial fibrillation (AF) treatment by United States cardiologists in the context of the American College of Cardiology, American Heart Association, and European Society of Cardiology guidelines after recent landmark clinical trials. Most patients in AFFECTS had AF without clinically significant structural heart disease or only uncomplicated hypertension. Among the all-enrolled population (n = 1,461), initial treatment strategies assigned were rhythm control in 64% and rate control in 36%. Among patients with either paroxysmal (n = 1,165) or persistent (n = 273) AF, 67% and 55%, respectively, were assigned rhythm control. The trend to assign rhythm control as the initial treatment goal decreased with age. In the rhythm-control group, most patients (74%) also received a rate-control agent during the registry, while 25% of those assigned to rate control received antiarrhythmic drugs. Most first prescriptions of antiarrhythmic drugs were for first-line therapy compliant with 2001 (76%) and 2006 (86%) guidelines. Most second prescriptions were for first-line therapies as well. Rates of serious adverse events were low. In conclusion, data from this study provide insight into community treatment patterns in patients with AF, most without clinically significant structural heart disease or with only uncomplicated hypertension.

The coronary artery calcium score and stress myocardial perfusion imaging provide independent and complementary prediction of cardiac risk

OBJECTIVES

This study sought to examine the relationship between coronary artery calcium score (CACS) and single-photon emission computed tomography (SPECT) results for predicting the short- and long-term risk of cardiac events.

BACKGROUND

The CACS and SPECT results both provide important prognostic information. It is unclear whether integrating these tests will better predict patient outcome.

METHODS

We followed-up 1,126 generally asymptomatic subjects without previous cardiovascular disease who had a CACS and stress SPECT scan performed within a close time period (median 56 days). The median follow-up was 6.9 years. End points analyzed were total cardiac events and all-cause death/myocardial infarction (MI).

RESULTS

An abnormal SPECT result increased with increasing CACS from <1% (CACS < or =10) to 29% (CACS >400) (p < 0.001). Total cardiac events and death/MI also increased with increasing CACS and abnormal SPECT results (p < 0.001). In subjects with a normal SPECT result, CACS added incremental prognostic information, with a 3.55-fold relative increase for any cardiac event (2.75-fold for death/MI) when the CACS was severe (>400) versus minimal (< or =10). Separation of the survival curves occurred at 3 years after initial testing for all cardiac events and at 5 years for death/MI.

CONCLUSIONS

The CACS and SPECT findings are independent and complementary predictors of short- and long-term cardiac events. Despite a normal SPECT result, a severe CACS identifies subjects at high long-term cardiac risk. After a normal SPECT result, our findings support performing a CACS in patients who are at intermediate or high clinical risk for coronary artery disease to better define those who will have a high long-term risk for adverse cardiac events.

Vernakalant Hydrochloride for Rapid Conversion of Atrial Fibrillation

Background— The present study assessed the efficacy and safety of vernakalant hydrochloride (RSD1235), a novel compound, for the conversion of atrial fibrillation (AF).

Methods and Results— Patients were randomized in a 2:1 ratio to receive vernakalant or placebo and were stratified by AF duration of 3 hours to 7 days (short duration) and 8 to 45 days (long duration). A first infusion of placebo or vernakalant (3 mg/kg) was given for 10 minutes, followed by a second infusion of placebo or vernakalant (2 mg/kg) 15 minutes later if AF was not terminated. The primary end point was conversion of AF to sinus rhythm for at least 1 minute within 90 minutes of the start of drug infusion in the short-duration AF group. A total of 336 patients were randomized and received treatment (short duration, n=220; long duration, n=116). Of the 145 vernakalant patients, 75 (51.7%) in the short-duration AF group converted to sinus rhythm (median time, 11 minutes) compared with 3 of the 75 placebo patients (4.0%; P <0.001). Overall, in the short- and long-duration AF groups, 83 of the 221 vernakalant patients (37.6%) experienced termination of AF compared with 3 of the 115 placebo patients (2.6%; P <0.001). Transient dysgeusia and sneezing were the most common side effects in vernakalant-treated patients. Four vernakalant-related serious adverse events (hypotension [2 events], complete atrioventricular block, and cardiogenic shock) occurred in 3 patients.

Conclusion— Vernakalant demonstrated rapid conversion of short-duration AF and was well tolerated.

Results of a non-specific immunomodulation therapy in chronic heart failure (ACCLAIM trial): a placebo-controlled randomised trial

BACKGROUND

Evidence suggests that inflammatory mediators contribute to development and progression of chronic heart failure. We therefore tested the hypothesis that immunomodulation might counteract this pathophysiological mechanism in patients.

METHODS

We did a double-blind, placebo-controlled study of a device-based non-specific immunomodulation therapy (IMT) in patients with New York Heart Association (NYHA) functional class II-IV chronic heart failure, left ventricular (LV) systolic dysfunction, and hospitalisation for heart failure or intravenous drug therapy in an outpatient setting within the past 12 months. Patients were randomly assigned to receive IMT (n=1213) or placebo (n=1213) by intragluteal injection on days 1, 2, 14, and every 28 days thereafter. Primary endpoint was the composite of time to death from any cause or first hospitalisation for cardiovascular reasons. The study continued until 828 primary endpoint events had accrued and all study patients had been treated for at least 22 weeks. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00111969.

FINDINGS

During a mean follow-up of 10.2 months, there were 399 primary events in the IMT group and 429 in the placebo group (hazard ratio 0.92; 95% CI 0.80-1.05; p=0.22). In two prespecified subgroups of patients--those with no history of previous myocardial infarction (n=919) and those with NYHA II heart failure (n=689)--IMT was associated with a 26% (0.74; 0.57-0.95; p=0.02) and a 39% (0.61; 95% CI 0.46-0.80; p=0.0003) reduction in the risk of primary endpoint events, respectively.

INTERPRETATION

Non-specific immunomodulation may have a role as a potential treatment for a large segment of the heart failure population, which includes patients without a history of myocardial infarction (irrespective of their functional NYHA class) and patients within NYHA class II.

Preoperative opacification of acrylic intraocular lenses in storage

The preoperative opacification of acrylic intraocular lenses (IOLs) was investigated in order to determine its cause. Opacified IOLs were examined by energy dispersive X-ray (EDX), the buffer solutions were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and the rubber seals used in the bottles in which the IOLs were stored were ashed and tested. The deposit covering the opacified lenses contained a significant amount of zinc, which was absent from fresh IOLs and buffer solution. The source of this was found to be the rubber seals used to seal the glass bottles in which the IOLs were stored. There were two types of rubber seals used, red and grey in colour. The buffer solutions in which opacification had occurred was also contaminated with zinc, but this was only noticeable when using the red seals. This contamination was reproduced by boiling red seals in fresh buffer solution for eighty minutes, to simulate autoclaving. It was concluded that zinc from the zinc oxide used as filler in the rubber seals was leaching into the buffer solution and causing the IOLs to become opacified. This was found to be much worse in the case of the red seals than for the grey ones. However, minute crystals were found on the IOLs stored using the grey ones, which could potentially act as nucleation points for postoperative opacification.

A Multinational Study to Establish the Value of Early Adenosine Technetium-99m Sestamibi Myocardial Perfusion Imaging in Identifying a Low-Risk Group for Early Hospital Discharge After Acute Myocardial Infarction

OBJECTIVES

The purpose of this study was to determine whether gated adenosine Tc-99m sestamibi single-photon emission computed tomography (ADSPECT) could accurately define risk and thereby guide therapeutic decision making in stable survivors of acute myocardial infarction (AMI).

BACKGROUND

Controversy continues as to the role of noninvasive stress imaging in stratifying risk early after AMI.

METHODS

The INSPIRE (Adenosine Sestamibi Post-Infarction Evaluation) trial is a prospective multicenter trial which enrolled 728 clinically stable survivors of AMI who had gated ADSPECT within 10 days of hospital admission and subsequent 1-year follow-up. Event rates were assessed within prospectively defined INSPIRE risk groups based on the adenosine-induced left ventricular perfusion defect size, extent of ischemia, and ejection fraction.

RESULTS

Total cardiac events/death and reinfarction significantly increased within each INSPIRE risk group from low (5.4%, 1.8%), to intermediate (14%, 9.2%), to high (18.6%, 11.6%) (p < 0.01). Event rates at 1 year were lowest in patients with the smallest perfusion defects but progressively increased when defect size exceeded 20% (p < 0.0001). The perfusion results significantly improved risk stratification beyond that provided by clinical and ejection fraction variables. The low-risk INSPIRE group, comprising one-third of all enrolled patients, had a shorter hospital stay with lower associated costs compared with the higher-risk groups (p < 0.001).

CONCLUSIONS

Gated ADSPECT performed early after AMI can accurately identify a sizeable low-risk group who have a <2% death and reinfarction rate at 1 year. Identifying these low-risk patients for early hospital discharge may improve utilization of health care resources at considerable cost savings.

An Initial Strategy of Intensive Medical Therapy Is Comparable to That of Coronary Revascularization for Suppression of Scintigraphic Ischemia in High-Risk But Stable Survivors of Acute Myocardial Infarction

OBJECTIVES

The purpose of this study was to determine the relative benefit of intensive medical therapy compared with coronary revascularization for suppressing scintigraphic ischemia.

BACKGROUND

Although medical therapies can reduce myocardial ischemia and improve patient survival after acute myocardial infarction, the relative benefit of medical therapy versus coronary revascularization for reducing ischemia is unknown.

METHODS

A prospective randomized trial in 205 stable survivors of acute myocardial infarction was made to define the relative efficacy of an intensive medical therapy strategy versus coronary revascularization for suppressing scintigraphic ischemia as assessed by serial gated adenosine Tc-99m sestamibi myocardial perfusion tomography. All patients at baseline had large total (> or =20%) and ischemic (> or =10%) adenosine-induced left ventricular perfusion defects and an ejection fraction > or =35%. Imaging was performed during 1 to 10 days of hospital admission and repeated in an identical fashion after optimization of therapy. Patients randomized to either strategy had similar baseline demographic and scintigraphic characteristics.

RESULTS

Both intensive medical therapy and coronary revascularization induced significant but comparable reductions in total (-16.2 +/- 10% vs. -17.8 +/- 12%; p = NS) and ischemic (-15 +/- 9% vs. -16.2 +/- 9%; p = NS) perfusion defect sizes. Likewise, a similar percentage of patients randomized to medical therapy versus coronary revascularization had suppression of adenosine-induced ischemia (80% vs. 81%; p = NS).

CONCLUSIONS

Sequential adenosine sestamibi myocardial perfusion tomography can effectively monitor changes in scintigraphic ischemia after anti-ischemic medical or coronary revascularization therapy. A strategy of intensive medical therapy is comparable to coronary revascularization for suppressing ischemia in stable patients after acute infarction who have preserved LV function.

Cumulative Experience of Azimilide-Associated Torsades de Pointes Ventricular Tachycardia in the 19 Clinical Studies Comprising the Azimilide Database

OBJECTIVES

The purpose of this study was to assess the incidence, temporal characteristics, and risk factors associated with azimilide-associated torsades de pointes (TdP) ventricular tachycardia.

BACKGROUND

Azimilide dihydrochloride is a class III antiarrhythmic drug possessing Ikr and Iks channel-blocking properties.

METHODS

Oral azimilide (75 to 125 mg/day) was taken by 5,375 patients in 19 clinical trials conducted at 775 international centers. Of 3,964 patients in double-blind studies, 1,427 had a history of atrial fibrillation or other supraventricular arrhythmia, 510 had an implantable cardioverter-defibrillator, and 2,027 were post-myocardial infarction patients with a left ventricular ejection fraction < or =35%.

RESULTS

The TdP occurred in 56 patients assigned to azimilide, was dose-related, and tended to occur earlier with an azimilide-loading regimen. Forty-three percent of TdP patients had a QT interval corrected by Bazett's formula, for heart rate, (QTc) > or =500 ms at the time of or before the TdP occurrence. Significant risk factors using logistic regression were increasing age, female gender, diuretic use, and lack of aspirin use.

CONCLUSIONS

Azimilide-associated TdP has characteristics and risk factors similar to other Ikr blockers. However, there is a distinctive temporal profile. The TdP events are not concentrated in the first week. The azimilide-associated TdP rate is 1% (95% confidence interval 0.78 to 1.35) and is not increased in patients with low left ventricular ejection fraction, even in women.

Electrical storm in patients with an implantable defibrillator: incidence, features, and preventive therapy: insights from a randomized trial

AIMS

The purpose of this study was to assess the incidence, features, and clinical sequelae of 'electrical storm' (ES).

METHODS AND RESULTS

This study is a prospectively designed secondary analysis of SHIELD; a randomized trial of azimilide for suppression of ventricular tachycardia/fibrillation (VT/VF) leading to implanted cardioverter defibrillator (ICD) therapies. Systematic and rigorous follow-up and blinded adjudication of ICD therapy allowed identification of all ESs (>/=3 separate VT/VF episodes leading to ICD therapies within 24 h). Of 633 ICD recipients, 148 (23%) experienced at least one ES over 1-year follow-up. No clinical predictors of ES were identified. Frequent VT episodes accounted for 91% of all ESs, with the remaining being VF alone or both VT plus VF. ES led to a 3.1-fold increase in arrhythmia-related hospitalization (95% CI 2.3-4.3; P<0.0001) compared with patients with isolated VT/VF, and to a 10.2-fold increase (95% CI 6.4-16.3; P<0.0001) compared with patients without VT/VF. Compared with placebo, azimilide (75 and 125 mg/day) reduced the risk of recurrent ES by 37% (HR=0.63, 95% CI 0.35-1.11, P=0.11) and 55% (HR=0.45, 95% CI 0.23-0.87, P=0.018), respectively. However, the reduction in time-to-first ES did not reach statistical significance by both doses (75 and 125 mg) of azimilide (HR=0.82, 95% CI 0.56-1.19, P=0.29 and HR=0.69, 95% CI 0.46-1.04, P=0.07), respectively.

CONCLUSION

ES is common and unpredictable in ICD recipients and it is a strong predictor of hospitalization.

Comparison of management patterns and clinical outcomes in patients with atrial fibrillation in Canada and the United States (from the analysis of the Atrial Fibrillation Follow-up Investigation of Rhythm Management [AFFIRM] database)

Little is known about differences in practice patterns or outcomes in the management of patients who have atrial fibrillation in Canada compared with those in the United States (US). We evaluated the effect that the country of enrollment may have on the management patterns and clinical outcomes in patients who participated in the AFFIRM study. Three thousand four hundred patients came from the US and 660 from Canada. In the US, patients were more likely to have a history of coronary artery disease (39% vs 35%, p = 0.03), hypertension (72% vs 67%, p = 0.01), or congestive heart failure (24% vs 18%, p = 0.0002). More US participants were <65 years of age (25% vs 19%, p = 0.003). Although at randomization the use of warfarin was comparable, during follow-up Canadians were more likely to be treated with warfarin and to be therapeutically anticoagulated. Mortality rate at 5 years was higher in US patients (24% vs 16%, p = 0.001), and the composite end point (death, disabling stroke, major bleeding, cardiac arrest, or anoxic encephalopathy) was also higher in US patients (30% vs 22%, p = 0.0005). Even after adjusting for known differences in baseline characteristics, the risk of death was lower in Canada (hazard ratio 0.70, p = 0.02). In conclusion, in the AFFIRM study, US subjects were more likely to have preexisting cardiovascular diseases despite being younger (<65 years old) than those in Canada. Effective warfarin therapy was more commonly employed in Canada. After correcting for the known differences in baseline characteristics, Canadian patients who had atrial fibrillation had a lower mortality risk.

Prognostic value of adenosine Tl-201 myocardial perfusion imaging after acute myocardial infarction: results of a prospective clinical trial

BACKGROUND

We have previously shown in retrospective studies that adenosine myocardial perfusion imaging (MPI) done after acute myocardial infarction (AMI) can effectively predict the risk of future cardiac events in these patients. The objective of this study was to validate these observations in a prospective clinical trial.

METHODS AND RESULTS

One hundred twenty-six stable patients underwent quantitative adenosine MPI at a mean of 4.5 +/- 2.9 days after AMI. On the basis of the MPI results, they were divided into 3 risk groups: low risk (< 20% perfusion defect), intermediate risk (> or = 20% perfusion defect with < 10% ischemia), and high risk (> or = 20% perfusion defect with > 10% ischemia). The patients were followed up for 11 +/- 5 months for the occurrence of cardiac events: death, myocardial infarction, unstable angina, or congestive heart failure. The actual event rates correlated very well with the prespecified risk groups (19% for the low-risk group, 28% for the intermediate-risk group, and 78% for the high-risk group; P < .001). The significant multivariate predictors for events were female gender (relative risk [RR], 2.90; P = .002), left ventricular ejection fraction (RR, 1.34; P = .04), and ischemic defect size (RR, 1.46; P = .001), with a global chi2 value of 26.7.

CONCLUSION

This study demonstrates, in a prospectively designed clinical trial, that quantitative adenosine MPI performed soon after AMI can effectively predict the risk of future cardiac events. These findings are currently being validated in an ongoing, large, multicenter, international clinical trial.

First experience with a Mobile Cardiac Outpatient Telemetry (MCOT) system for the diagnosis and management of cardiac arrhythmia

Recently, a mobile cardiac outpatient telemetry (MCOT) system has become available that monitors the electrocardiogram continuously, recognizes arrhythmias automatically, and transmits abnormal rhythms instantaneously. MCOT does not require activation by the patient. We report data from the first 100 consecutive patients monitored by this new technology.

Design of the SHock Inhibition Evaluation with Azimilide (SHIELD) study: a novel method to assess antiarrhythmic drug effect in patients with an implantable cardioverter-defibrillator

This report presents the rationale and study design details of the SHock Inhibition Evaluation with Azimilide study, which is recruiting 624 patients with implantable cardioverter-defibrillators (ICDs) who are at risk for life-threatening ventricular arrhythmia, randomized to azimilide 75 mg, azimilide 125 mg, or placebo and followed for 1 year. The objective of this study is to determine the effect of azimilide versus placebo on the symptomatic ventricular arrhythmia burden using a unique statistical analysis based on the unusual temporal distribution of symptomatic ICD therapies. The primary efficacy end points are time to all-cause shocks and time to all-cause shocks plus symptomatic ventricular arrhythmic events triggering antitachycardia pacing measured from randomization.

Placebo-Controlled, Randomized Clinical Trial of Azimilide for Prevention of Ventricular Tachyarrhythmias in Patients With an Implantable Cardioverter Defibrillator

BACKGROUND

Although implanted cardioverter defibrillators (ICDs) effectively treat sustained ventricular tachyarrhythmias, up to 50% of ICD recipients eventually require concomitant antiarrhythmic drug therapy to prevent symptomatic arrhythmia recurrences and hence reduce the number of device therapies.

METHODS AND RESULTS

A total of 633 ICD recipients were enrolled in a randomized, double-blind, placebo-controlled study to evaluate the effect of daily doses of 75 or 125 mg of azimilide on recurrent symptomatic ventricular tachyarrhythmias and ICD therapies. Total all-cause shocks plus symptomatic ventricular tachycardia (VT) terminated by antitachycardia pacing (ATP) were significantly reduced by azimilide, with relative risk reductions of 57% (hazard ratio [HR]=0.43, 95% CI 0.26 to 0.69, P=0.0006) and 47% (HR=0.53, 95% CI 0.34 to 0.83, P=0.0053) at 75- and 125-mg doses, respectively. The reductions in all-cause shocks with both doses of azimilide did not achieve statistical significance. The incidence of all appropriate ICD therapies (shocks or ATP-terminated VT) was reduced significantly among patients taking 75 mg of azimilide (HR=0.52, 95% CI 0.30 to 0.89, P=0.017) and those taking 125 mg of azimilide (HR=0.38, 95% CI 0.22 to 0.65, P=0.0004). Five patients in the azimilide groups and 1 patient in the placebo group had torsade de pointes; all were successfully treated by the device. One patient taking 75 mg of azimilide had severe but reversible neutropenia.

CONCLUSIONS

Azimilide significantly reduced the recurrence of VT or ventricular fibrillation terminated by shocks or ATP in ICD patients, thereby reducing the burden of symptomatic ventricular tachyarrhythmia.

Adenosine sestamibi SPECT post-infarction evaluation (INSPIRE) trial: A randomized, prospective multicenter trial evaluating the role of adenosine Tc-99m sestamibi SPECT for assessing risk and therapeutic outcomes in survivors of acute myocardial infarction

BACKGROUND

Preliminary studies indicate that adenosine myocardial perfusion single photon tomography (SPECT) can safely and accurately stratify patients into low and high risk groups early after acute myocardial infarction (AMI).

METHODS AND RESULTS

INSPIRE is a prospective, randomized multicenter trial which enrolled 728 clinically stable survivors of AMI. Following baseline adenosine sestamibi gated SPECT, patients were classified as low, intermediate or high risk based on the quantified total and ischemic left ventricular (LV) perfusion defect size (PDS). A subset of high risk patients with a LV ejection fraction > or =35% were randomized to a strategy of either intensive medical therapy or coronary revascularization. Adenosine SPECT was repeated at 6-8 weeks to determine the relative effects of anti-ischemic therapies on total and ischemic PDS (primary endpoint). All patients were followed for one year. The baseline demographic, clinical and scintigraphic characteristics of the study population are presented. Adenosine SPECT was performed within 1 day of admission in 12% of patients and in 64% by Day 4.

CONCLUSION

The unique study design features of INSPIRE will further clarify the role of adenosine sestamibi SPECT in defining initial patient risk after AMI and in monitoring the benefits of intensive anti-ischemic therapies.

The efficacy of azimilide in the treatment of atrial fibrillation in the presence of left ventricular systolic dysfunction

OBJECTIVES

The purpose of this study was to assess the effect of oral azimilide dihydrochloride (AZ) 100 mg versus placebo on the onset, termination, and prevalence of atrial fibrillation (AF) in a subpopulation of patients in the Azimilide Postinfarct Survival Evaluation (ALIVE) trial.

BACKGROUND

Previous clinical trials have demonstrated the antiarrhythmic effects of AZ in patients with AF. Azimilide was investigated for its effects on mortality in patients with depressed left ventricular (LV) function after recent myocardial infarction (MI) and in a subpopulation of patients with AF.

METHODS

A total of 3,381 post-MI patients with depressed LV function were enrolled in this randomized, placebo-controlled, double-blind study of AZ 100 mg on all-cause mortality. A total of 93 patients had AF on the baseline 12-lead electrocardiogram (ECG). An additional 27 patients developed AF after initially being in sinus rhythm at randomization. These patients were identified through 12-lead ECGs obtained during routine visits at week 2, months 1, 4, 8, and 12.

RESULTS

Patients with AF at baseline had a higher mortality than those without AF (p = 0.0006). Among AF patients, there was no difference in mortality between AZ patients and placebo patients (p = 0.82). Fewer AZ patients developed AF than placebo patients (p = 0.04). More AZ patients than placebo patients converted to sinus rhythm, but this difference did not achieve statistical significance (p = 0.076). Over one-year follow-up, more AZ patients were in sinus rhythm than placebo patients (p = 0.04).

CONCLUSIONS

Azimilide was safe and effective AF therapy in patients with depressed LV function after an MI.

Mortality in patients after a recent myocardial infarction: a randomized, placebo-controlled trial of azimilide using heart rate variability for risk stratification

BACKGROUND

Depressed left ventricular function (LVF) and low heart rate variability (HRV) identify patients at risk of increased mortality after myocardial infarction (MI). Azimilide, a novel class III antiarrhythmic drug, was investigated for its effects on mortality in patients with depressed LVF after recent MI and in a subpopulation of patients with low HRV.

METHODS AND RESULTS

A total of 3717 post-MI patients with depressed LVF were enrolled in this randomized, placebo-controlled, double-blind study of azimilide 100 mg on all-cause mortality. Placebo patients with low HRV had a significantly higher 1-year mortality than those with high HRV (>20 U; 15% versus 9.5%, P<0.0005) despite nearly identical ejection fractions. No significant differences were observed between the 100-mg azimilide and placebo groups for all-cause mortality in either the "at-risk" patients identified by depressed LVF (12% versus 12%) or the subpopulation of "high-risk" patients identified by low HRV (14% versus 15%) or for total cardiac or arrhythmic mortality. Significantly fewer patients receiving azimilide developed atrial fibrillation than did patients receiving placebo (0.5% versus 1.2%, P<0.04). The incidences of torsade de pointes and severe neutropenia (absolute neutrophil count < or =500 cells/microL) were slightly higher in the azimilide group than in the placebo group (0.3% versus 0.1% for torsade de pointes and 0.9% versus 0.2% for severe neutropenia).

CONCLUSIONS

Azimilide did not improve or worsen the mortality of patients after MI. Low HRV independently identified a subpopulation at high risk of mortality.

Pure class III agents for prevention of sudden cardiac death

The results of clinical trials in postmyocardial infarction patients using type I antiarrhythmic drugs have been disappointing. There was optimism that IKr blockers might result in a reduction in sudden cardiac death in postinfarct population. Four trials are reviewed here, and the results are variable. The four drugs reviewed--d,l-sotalol, d-sotalol, dofetilide, and azimilide--all share IKr-blocking properties. In addition, d,l-sotalol is a beta-blocker and azimilide is an IKs blocker. The primary uses of d,l-sotalol, dofetilide, and, if approved, azimilide are currently for treatment of atrial fibrillation. Thus, the mortality trials reviewed here are primarily used as support of safety in high-risk patients, because none has achieved a mortality reduction in postinfarction patients. These trials play pivotal roles for regulatory approval of these drugs for use in atrial fibrillation.

Analysis of the cilostazol safety database

Cilostazol, a type III phosphodiesterase inhibitor, was approved in the United States in 1999 for the reduction of the symptoms of intermittent claudication. This article summarizes the safety data from 8 cilostazol phase 3 controlled clinical trials, involving 2,702 patients: 1,374 receiving cilostazol, 973 assigned to placebo, and 355 taking pentoxifylline. The trials ranged from 12 to 24 weeks in duration. There were a total of 475 patient-exposure years on cilostazol, 357 patient-exposure years on placebo, and 135 patient-exposure years on pentoxifylline. Headache, diarrhea, and other gastrointestinal complaints were seen more often in cilostazol-treated than placebo-treated patients; pharyngitis and nausea were more common in pentoxifylline-treated than placebo-treated patients. Headache requiring discontinuation occurred in 1.3% of patients taking cilostazol 50 mg bid and 3.7% of those receiving cilostazol 100 mg bid, compared with 0.3% of placebo-treated patients. Discontinuations due to diarrhea, palpitations, or myocardial infarction were similar in cilostazol-, placebo-, and pentoxifylline-treated patients. The rate of serious cardiovascular events was similar in all 3 treatment groups. Myocardial infarction occurred in 1.0% of cilostazol-treated, 0.8% of placebo-treated, and 1.1% of pentoxifylline-treated patients. The incidence of stroke was 0.5% in both cilostazol- and placebo-treated patients and 1.1% in pentoxifylline-treated patients. Total cardiovascular morbidity and all-cause mortality was 6.5% for cilostazol 100 mg bid, 6.3% for cilostazol 50 mg bid, and 7.7% for placebo. There were 16 deaths occurring in 0.6%, 0.5%, and 0.6% of cilostazol-, placebo-, and pentoxifylline-treated patients, respectively. The evaluations showed no trend toward increased cardiovascular morbidity or mortality risk in patients receiving cilostazol. In addition, postmarketing surveillance in the United States, representing 70,430 patient-years of cilostazol exposure, has shown minimal accounts of myocardial infarction, stroke, or death. The safety profile of cilostazol in doses of 50 mg bid and 100 mg bid appears to offer an acceptable risk-benefit ratio in patients with intermittent claudication.

Central clinical research issues in electrophysiology: report of the NASPE Committee

This article contains the results of an attempt by appointed members of the North American Society of Pacing and Electrophysiology to define the research frontier in electrophysiology and suggest areas of study as an aid in setting the research agenda.

Hemodynamic effects of tezosentan, an intravenous dual endothelin receptor antagonist, in patients with class III to IV congestive heart failure

BACKGROUND

Endothelin-1, a powerful mediator of vasoconstriction, is increased in patients with congestive heart failure and appears to be a prognostic marker that strongly is correlated with the severity of disease. However, little is known about the potential immediate beneficial effects of acute blockade of the endothelin system in patients with symptomatic left ventricular dysfunction. We assessed the hemodynamic effects and safety of tezosentan, an intravenous dual endothelin receptor antagonist, in patients with moderate to severe heart failure.

METHODS AND RESULTS

This randomized placebo-controlled study evaluated the hemodynamic effects of 6-hour infusions of tezosentan at 5, 20, 50, and 100 mg/h compared with placebo in 61 patients with New York Heart Association class III to IV heart failure. Plasma endothelin-1 and tezosentan concentrations were also determined. Treatment with tezosentan caused a dose-dependent increase in cardiac index ranging from 24.4% to 49.9% versus 3.0% with placebo. Tezosentan also dose-dependently reduced pulmonary capillary wedge pressure and pulmonary and systemic vascular resistances, with no change in heart rate. No episodes of ventricular tachycardia or hypotension requiring drug termination were observed during tezosentan infusion. Tezosentan administration resulted in dose-related increased plasma endothelin-1 concentrations.

CONCLUSIONS

The present study demonstrated that tezosentan can be safely administered to patients with moderate to severe heart failure and that by virtue of its ability to antagonize the effects of endothelin-1, it induced vasodilatory responses leading to a significant improvement in cardiac index. Further studies are under way to determine the clinical effects of tezosentan in the setting of acute heart failure.

Severity of coronary artery calcification by electron beam computed tomography predicts silent myocardial ischemia

BACKGROUND

Detection of subclinical coronary artery disease (CAD) before the development of life-threatening cardiac complications has great potential clinical relevance. Electron beam computed tomography (EBCT) is currently the only noninvasive test that can detect CAD in all stages of its development and thus has the potential to be an excellent screening technique for identifying asymptomatic subjects with underlying myocardial ischemia.

METHODS AND RESULTS

Over 2.5 years, we prospectively studied 3895 generally asymptomatic subjects with EBCT, 411 of whom had stress myocardial perfusion tomography (SPECT) within a close (median, 17 days) time period. SPECT and exercise treadmill results were compared with the coronary artery calcium score (CACS) as assessed by EBCT. The total CACS identified a population at high risk for having myocardial ischemia by SPECT although only a minority of subjects (22%) with an abnormal EBCT had an abnormal SPECT. No subject with CACS <10 had an abnormal SPECT compared with 2.6% of those with scores from 11 to 100, 11.3% of those with scores from 101 to 399, and 46% of those with scores >/=400 (P<0.0001). CACS predicted an abnormal SPECT regardless of subject age or sex.

CONCLUSIONS

CACS identifies a high-risk group of asymptomatic subjects who have clinically important silent myocardial ischemia. Our results support the role of EBCT as the initial screening tool for identifying individuals at various stages of CAD development for whom therapeutic decision making may differ considerably.

Cost estimates for treatment of cardiac ischemia (from the Asymptomatic Cardiac Ischemia Pilot [ACIP] study)

Costs for management of myocardial ischemia are enormous, yet comparison cost and outcome data for various ischemia treatment strategies from randomized trials are lacking and will require cost and resource utilization data from a large prospective trial. The Asymptomatic Cardiac Ischemia Pilot provided feasibility data for planning such a trial and an opportunity to estimate the long-term costs of different treatment strategies. Economic implications for ischemia management were compared in 558 patients with stable coronary artery disease and myocardial ischemia during both stress testing and daily life. Participants were randomized to 3 different initial treatment strategies and followed for 2 years. Based on cost trends over follow-up, costs for subsequent care were estimated. As expected, due to initial procedural costs, at 3 months, estimated costs for revascularization were approximately 10 times greater than costs for a medical care strategy. Extrapolated costs for anticipated resource consumption for care beyond 2 years, however, were approximately 2 times greater for an initial medical care strategy than for initial revascularization. This was due to increased need for drugs and hospitalizations for both late revascularizations and other ischemia-related events. Estimated costs for anticipated care in the medical strategies reached the anticipated cost of the revascularization strategy within 10 years. Because this cost-equal time period is well within the median life expectancy for such a patient population, these findings could have important public health implications and require testing in a full-scale prognosis trial. We anticipate that over the patients' life expectancy, early revascularization is likely to become either cost-neutral or cost-effective.

Evaluation of antiarrhythmic drug efficacy in patients with an ICD. Unlimited potential or replete with complexity and problems?

A report from a Study group, proposed by A. J. Camm, London, of the Working Groups on Arrhythmias and Cardiac Pacing of the European Society of Cardiology; co-sponsored by the North American Society of Pacing and Electrophysiology. The Study Group was convened on 29 August 1997 at Saltsjöbaden, near Stockholm. The meeting was chaired by A. J. Camm, London, and C. M. Pratt, Houston. Based on the presentation and discussions, a first draft of the documents was prepared by C. Pratt and J. Camm which was then circulated to all members three times for their review. All members of the Study Group approved the final manuscript. This report represents the opinion of the members of this Study Group and does not necessarily reflect the official position of either society.The meeting of the Study Group was made possible by unrestricted educational grants from Medtronic, Guidant, Proctor & Gamble, Berlex and Sanofi.Also, presented, in part, at the Cardio-Renal Drugs Advisory Board meeting of the Food and Drug Administration, Bethesda, Maryland, on 30 April 1999.

Evaluation of antiarrhythmic drug efficacy in patients with an ICD: unlimited potential or replete with complexity and problems?

There are a number of novel ways in which implantable cardioverter defibrillator (ICD) endpoints can be used in clinical trials to evaluate antiarrhythmic drugs. The advances in ICD technology (storage, retrieval, and accurate interpretation of ICD electrograms) expand the potential to include the use of an ICD endpoint as a clinical surrogate for sudden death. The ICD also provides the necessary safety net to test new drugs. The frequent need for antiarrhythmic drugs in patients already fitted with an ICD (e.g., for atrial fibrillation) necessitates knowledge of the drugs' effect on defibrillator threshold. There are interpretative problems and challenges associated with all types of ICD trials. A particular difficult issue is the degree to which the results of data on antiarrhythmic drug efficacy and safety acquired in the context of an ICD endpoint trial might be extrapolated to patient populations in which the device is not used. These and other challenging issues are discussed, with the goal of enhancing the design and interpretation of clinical trials featuring ICD endpoints.

Cardiovascular safety of fexofenadine HCl

Fexofenadine HCl is the acid metabolite of terfenadine (Seldane). The effect of this recently approved nonsedating antihistamine on the corrected QT interval (QTc) was evaluated in dose-tolerance, safety, and drug-interaction studies with healthy volunteers, and in clinical studies in patients with seasonal allergic rhinitis (SAR). Twelve-lead electrocardiographic data were collected once before and after dosing or serially throughout these studies. Outliers were defined as QTc > 440 ms with a > or = 10 ms increase from baseline. The recommended fexofenadine HCl dose is 60 mg twice daily. Fexofenadine HCl doses up to 800 mg once daily or 690 mg twice daily for 28 days resulted in no dose-related increases in QTc. Longer term studies indicated no statistically significant QTc increases compared with placebo in patients receiving fexofenadine HCl 80 mg twice daily for 3 months, 60 mg twice daily for 6 months, or 240 mg once daily for 12 months. Interaction studies showed no significant increases in QTc when fexofenadine HCl 120 mg twice daily was administered in combination with erythromycin (500 mg 3 times daily) or ketoconazole (400 mg once daily) after dosing to steady state (6.5 days). Clinical trials in patients with SAR (n = 1,160) treated with 40, 60, 120, or 240 mg twice-daily fexofenadine HCl or placebo indicated no dose-related increases in QTc and no statistically significant increases in mean QTc compared with placebo. In controlled trials with approximately 6,000 persons, no case of fexofenadine-associated torsades de pointes was observed. The frequency and magnitude of QTc outliers were similar between fexofenadine HCl and placebo in all studies. Based on a large clinical database, we conclude that fexofenadine HCl has no significant effect on QTc, even at doses > 10-fold higher than that is efficacious for SAR.

Predicting antiarrhythmic performance

Antiarrhythmic therapy in the past was guided by observational studies. However, optimum patient care now demands evidence derived from large clinical trials. Unfortunately, because large-scale mortality trials are expensive and time consuming, surrogate markers were used in many clinical studies. However, the use of surrogate markers for antiarrhythmic drug efficacy was called into question after the publication of studies such as the Cardiac Arrhythmia Suppression Trial (CAST) and the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial. Currently, in order to predict antiarrhythmic performance, clinicians must rely on mortality trials for guidance in treating atrial and ventricular arrhythmias. Although the practicing physician has a large number of studies to draw from, the study design and patient population are critical variables that must be understood before trial results can be applied to patient care. This review focuses on the results of the major clinical antiarrhythmic drug trials published in the last 10 years. Patient variables (e.g., the presence or absence of structural heart disease) and problems in study design that may have affected outcome are emphasized as an aid to interpreting results of current and future clinical trials.

Factors influencing clinical outcomes after revascularization in the asymptomatic cardiac ischemia pilot (ACIP). ACIP Study Group

BACKGROUND AND AIM

The Asymptomatic Cardiac Ischemia Pilot is the first randomized trial where revascularization involved choice of either coronary bypass or angioplasty used in an early or a delayed symptom-driven approach. One-year outcomes were favorable (reduced recurrent ischemia and adverse outcomes) for an early revascularization strategy (within 4 weeks), compared with an early medical strategy when revascularization was delayed until symptom-driven. This ancillary study examined variables influencing outcomes after these 2 revascularization approaches (early vs. delayed until symptom-driven).

METHODS

Participants were clinically stable coronary disease patients with stress-induced and daily life ischemia who underwent revascularization. Characteristics associated with clinical outcomes occurring within the year following revascularization were examined using Cox regression analysis.

RESULTS

A total of 262 patients received revascularization; 170 in the early approach and 92 in the delayed symptom-driven approach. Thirty-three patients had adverse outcomes (death, nonfatal myocardial infarction, or repeat revascularization) during 1-year follow-up. The most important independent predictor of improved outcome during the follow-up year was attempted revascularization of > or = 66% of vessels with significant stenosis for the early (risk ratio [RR] 0.25, 95% confidence interval [CI] 0.09-0.67) and the delayed (RR 0.21, CI 0.08-0.58) approaches. Factors such as age, stress test results, and coronary angiographic findings did not predict clinical outcome.

CONCLUSIONS

Our findings are important in the planning of a large trial with longer follow-up.

Intensive medical therapy versus coronary angioplasty for suppression of myocardial ischemia in survivors of acute myocardial infarction: a prospective, randomized pilot study

BACKGROUND

Patients who have inducible ischemia after acute myocardial infarction (AMI) generally undergo coronary angiography with the intent to revascularize. Whether this approach is superior to intensive treatment with anti-ischemic medications is unknown.

METHODS AND RESULTS

We performed a prospective, randomized pilot study comparing intensive medical therapy with coronary angioplasty (PTCA) for suppression of myocardial ischemia in 44 stable survivors of AMI. Myocardial ischemia was quantified with adenosine 201Tl tomography (SPECT) performed 4.5+/-2.9 days after AMI. All patients at baseline had a large total (>/=20%) and ischemic (>/=10%) left ventricular perfusion defect size (PDS). SPECT was repeated at 43+/-26 days after therapy was optimized. The total stress-induced PDS was comparably reduced with medical therapy (from 38+/-13% to 26+/-16%; P<0.0001) and PTCA (from 35+/-12% to 20+/-16%; P<0.0001). The reduction in ischemic PDS was also similar (P=NS) in both groups. Cardiac events occurred in 7 of 44 patients over 12+/-5 months. Patients who remained clinically stable had a greater reduction in ischemic PDS (-13+/-9%) than those who had a recurrent cardiac event (-5+/-7%; P<0.02). Event-free survival was superior in the 24 patients who had a significant (>/=9%) reduction in PDS (96%) compared with those who did not (65%; P=0.009).

CONCLUSIONS

In this small pilot study, intensive medical therapy and PTCA were comparable at suppressing ischemia in stable patients after AMI. Sequential imaging with adenosine SPECT can track changes in PDS after anti-ischemic therapies and thereby predict subsequent outcome. Corroboration of these preliminary findings in a larger cardiac-event trial is warranted.

Transdermal nitroglycerin patch therapy improves left ventricular function and prevents remodeling after acute myocardial infarction: results of a multicenter prospective randomized, double-blind, placebo-controlled trial

BACKGROUND

Nitrates are widely used in the treatment of angina in patients with acute myocardial infarction (AMI). Short-term administration prevents left ventricular (LV) dilation and infarct expansion. However, little information is available regarding their long-term effects on LV remodeling in patients surviving Q-wave AMI.

METHODS AND RESULTS

This was a randomized, double-blind, placebo-controlled trial designed to investigate the long-term (6-month) efficacy of intermittent transdermal nitroglycerin (NTG) patches on LV remodeling in 291 survivors of AMI. Patients meeting entry criteria had baseline gated radionuclide angiography (RNA) followed by randomization to placebo or active NTG patches delivering 0.4-, 0.8-, or 1.6-mg/h. RNA was repeated at 6 months and 6.5 days after withdrawal of double-blind medication. The primary study end point was the change in end-systolic volume index (ESVI). Both ESVI and end-diastolic volume index (EDVI) were significantly reduced with 0.4-mg/h NTG patches (-11.4 and -11.6 mL/m2, respectively, P<.03). This beneficial effect was observed primarily in patients with a baseline LV ejection fraction < or =40% (deltaESVI, -31 mL/m2; deltaEDVI, -33 mL/m2; both P<.05) and only at the 0.4-mg/h dose. After NTG patch withdrawal, ESVI significantly increased but did not reach pretreatment values.

CONCLUSIONS

Transdermal NTG patches prevent LV dilation in patients surviving AMI. The beneficial effects are limited to patients with depressed LV function and only at the lowest (0.4-mg/h) dose. Continued administration is necessary to maintain efficacy. Whether these remodeling effects confer a clinical or survival advantage will need to be addressed in an adequately powered cardiac event trial.

Mortality in the Survival With ORal D-sotalol (SWORD) trial: why did patients die?

The Survival With ORal D-sotalol (SWORD) trial tested the hypothesis that the prophylactic administration of oral d-sotalol would reduce total mortality in patients surviving myocardial infarction (MI) with a left ventricular ejection fraction (LVEF) of < or = 40%. Two index MI groups were included: recent (6 to 42 days) and remote (> 42 days) with clinical heart failure (n = 915 and 2,206, respectively). The trial was discontinued when the statistical boundary for harm was crossed (RR = 1.65; p = 0.006). All baseline variables known to be associated with mortality risk (e.g., LVEF, heart failure class, age) as well as variables related to torsades de pointes (e.g., time from beginning of therapy, QTc, gender, potassium, renal function, dose of d-sotalol) were assessed for interaction of each variable with treatment assignment, computing RR and 95% confidence interval (CI) from Cox regression models. The d-sotalol-associated mortality was greatest in the group with remote MI and LVEFs of 31% to 40% (RR = 7.9; 95% CI 2.4 to 26.2). Most variables known to be associated with torsades de pointes were not differentially predictive of d-sotalol-associated risk, except female gender (RR = 4.7; 95% CI 1.4 to 16.5). These findings suggest that (1) most of the d-sotalol-associated risk was in patients remote from MI with a LVEF of 31% to 40%; comparable placebo patients had a very low mortality (0.5%); and (2) very little objective data supports torsades de pointes or any specific proarrhythmic mechanism as an explanation for d-sotalol-associated mortality risk.

Can antiarrhythmic drugs survive survival trials?

Sudden cardiac death due to arrhythmic events is the major cause of mortality among early post-myocardial infarction (MI) patients, accounting for > 250,000 deaths annually in the United States alone. Antiarrhythmic drugs can be used in such patients as well as in those who have not had a recent MI but are at high risk for sudden cardiac death (e.g., those with ventricular tachycardia/fibrillation, or who have survived cardiac arrest). Most antiarrhythmic drugs available, however, have limitations arising from their toxic and proarrhythmic potential. Thus, research and development of new agents and treatment modalities are desirable. This article seeks to enumerate the lessons of past clinical trials with these agents and to provide guidelines for future trials. That a variety of antiarrhythmic drugs have been associated with an increased mortality has been a disturbing observation. It is therefore imperative that candidates for antiarrhythmic therapy be selected appropriately. We recommend that future clinical trials use stringent criteria for the identification of patients at "high risk" for arrhythmia or sudden cardiac death, and limit recruitment to such patients. Traditional markers, such as the increased frequency and complexity of ventricular premature beats, and low left ventricular ejection fraction, have not been successful in identifying these high-risk patients. However, decreased heart rate variability and cardiac late potentials recorded on a signal-over-aged electrocardiogram appear to be more specific markers of post-MI arrhythmia or sudden cardiac death and may, in conjunction with the traditional markers, be used to improve selection of trial populations. Since the risk of sudden cardiac death diminishes with time after MI, it is also recommended that the temporal window of treatment with antiarrhythmic agents be limited to 1 year post-MI. It is also important to define clearly the endpoints of efficacy evaluations. A short-term reduction on markers like ventricular ectopic beats, for example, does not translate into a long-term decrease in arrhythmia-related mortality. Therefore, a reduction in overall mortality is the only meaningful endpoint to define the true risk-benefit ratio. To limit exposure to the potentially adverse effects of these agents, target populations for prophylactic antiarrhythmic drugs should be limited to recent post-MI patients at high risk for sudden cardiac death due to arrhythmia. Avoiding exposure of low-risk patients to antiarrhythmic drugs is equally imperative. "Low risk" of all-cause mortality includes the group of post-MI patients with a left ventricular ejection fraction >36%. Risk must be continuously evaluated in the setting of other pharmacologic (angiotensin-converting enzyme [ACE] inhibitors, aspirin, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors ["statins"], and others) and/or nonpharmacologic interventions (coronary artery bypass graft, angioplasty, implantable cardioverter/defibrillator). There is also a need to improve noninvasive techniques for identifying patients in the high-risk category-at present, the presence of ventricular premature beats and a left ventricular ejection fraction <36% is considered somewhat predictive of sudden cardiac death. Thus, patients with a recent MI and moderately low left ventricular ejection fraction (< or = 36% but not <20%) may be considered for antiarrhythmic therapy. A subset analysis of patients with low heart rate variability can provide valuable additional information. It is important to note that although all-cause mortality is a valid endpoint for such trials, stratification by specific cause of mortality is desirable.

The azimilide post-infarct survival evaluation (ALIVE) trial

The AzimiLide post-Infarct surVival Evaluation (ALIVE) trial is a new clinical trial using an innovative design to examine the potential of azimilide, a novel type of antiarrhythmic, for improving survival in post myocardial infarction (MI) patients at high risk of sudden cardiac death. Azimilide is the first of a unique class of antiarrhythmic drugs that blocks both slow and rapid components of the delayed rectifier potassium currents in human myocardium. Preclinical studies have shown the drug to be effective in reducing cardiac tachyarrhythmias, even under ischemic conditions. Currently, azimilide is in Phase III trials for the treatment of supraventricular arrhythmias. The ALIVE study design is based on lessons learned from the Cardiac Arrhythmia Suppression Trials (CAST), the Survival With Oral d-Sotalol (SWORD) trial, and the European Myocardial Infarction Amiodarone Trial (EMIAT) and identifies recent post-MI patients at high risk of sudden cardiac death. The hypothesis underlying this trial is that azimilide will improve survival in this patient population. The ALIVE trial is designed as a double-blind, placebo-controlled, multinational trial that will overcome the shortcomings of previous antiarrhythmic trials by using left ventricular ejection fraction and heart rate variability as predictors to target a post-MI patient population at high risk of sudden death. The major inclusion criteria for the study are adult patients of either gender with a left ventricular ejection fraction of 15-35% who have had a recent MI (within 6-21 days). Additional stratification will be based on patients with heart rate variability < or = 20 U (heart rate variability index). Exclusion criteria include factors that may predispose a patient to nonarrhythmia-induced death or to low risk of sudden cardiac death caused by arrhythmia. Sample size is based on the assumption that the all-cause mortality rate (the primary endpoint) for 1 year in placebo patients at high risk for sudden cardiac death (heart rate variability < or = 20 U) is 15% and that azimilide will decrease all-cause mortality by at least 45% in these patients. The trial consists of 3 groups-patients receiving 75 mg azimilide orally each day, patients receiving 100 mg azimilide orally each day, and patients receiving placebo. No dose adjustments for age, gender, renal or hepatic failure, or concomitant use of warfarin or digoxin are thought necessary with azimilide. Enrollment for the trial is expected to continue for 24 months, and treatment is scheduled to be administered for a 1-year follow-up period.