Review of the ATLAS trial

Low vs high dose of ACEi in systolic heart failure

Circulation 1999;100:2312-2318

Background: The CONSENSUS and SOLVD trials established the effectiveness of angiotensin converting enzyme inhibitors (ACEi) in reducing mortality and morbidity in patients with systolic heart failure. Both trials used enalapril with a target dose of 20mg twice a day (max dose) in the CONSENSUS trial and 10mg twice a day (medium dose) in the SOLVD trials. In real-world settings, ACEi are sometimes prescribed at lower doses, likely reflecting concerns about adverse effects or patients’ tolerance. It was unclear whether the benefit from low doses of ACEi is comparable to high doses.

The Assessment of Treatment with Lisinopril and Survival (ATLAS) trial sought to assess the efficacy and safety of low vs high doses of ACE inhibition in patients with systolic heart failure.

Patients: Eligible patients had left ventricular ejection fraction of 30% or less and had NYHA class II, III or IV despite treatment with diuretics for two or more months.

Patients were excluded if they had any of the following: Acute coronary syndrome or revascularization procedure within 2 months, history of sustained or symptomatic ventricular tachycardia, known intolerance to ACEi, serum creatinine >2.5 mg/dL, or any noncardiac condition that could limit survival.

Baseline characteristics: The trial randomized 3,164 patients – 1,596 randomized to the low-dose arm and 1,568 to the high dose arm.

The average age of patients was 64 years and 80% were men. The average left ventricular ejection fraction was 23%. Cardiomyopathy was ischemic in 65% of the patients. The NYHA class was II in 16% of the patients, III in 77% and IV in 7%.

Data on baseline comorbid conditions were not provided in the main manuscript.

Procedures: The study was double blinded. At the beginning of the study, all patients received open-label lisinopril for four weeks to assess who is able to tolerate the drug. Patients who were able to tolerate lisinopril 12.5 mg to15 mg daily for two or more weeks were randomized in a 1:1 ratio to receive low-dose or high-dose ACEi. The target dose of lisinopril in the lose dose group was 2.5 to 5.0mg daily and was 32.5 to 35mg daily in the high dose group.

All patients received open-label lisinopril 2.5 to 5mg daily. This dose was selected by the investigator. In addition, patients received up to three 10mg tablets of lisinopril or matching placebo.

Endpoints: The primary endpoint was all-cause mortality. Secondary end points included cardiovascular mortality, all-cause hospitalization and cardiovascular hospitalizations.

Analysis was performed based on the intention-to-treat principle. The estimated sample size was 3,000 patients. This sample size had 90% power at 5% alpha to detect 15% relative risk difference in the mortality between both treatment groups assuming 19% 1-year mortality in the high dose group.

Results: Of the 3,793 patients who entered the initial open-label tolerability phase, 83.4% were randomized. A total of 176/3,793 (4.6%) were withdrawn for possible side effects. The median follow-up time was 46 months.

Target doses were achieved in 92.7% of the patients in the low-dose group and 91.3% in the high-dose group. Study medication was discontinued by 30.6% of patients in the low-dose group and 27.2% in the high-dose group.

All-cause mortality was not significantly different between both treatment groups (44.9% with low dose vs 42.5% with high dose, HR: 0.92, 95% CI: 0.82 – 1.03; p= 0.128). Cardiovascular mortality was numerically lower in the high dose group but this was not statistically significant (37.2% vs 40.2%, HR: 0.90, 95% CI: 0.81 – 1.01; p= 0.073). All-cause hospitalization was lower in the high dose group (3,819 hospitalizations vs 4,397; p= 0.021). Hospitalizations for cardiac causes and hospitalizations for heart failure were also lower in the high dose group (2,456 vs 2,923; p= 0.05) and (1,199 vs 1,576; p= 0.002), respectively.

Patients in the high-dose group experienced more dizziness (19% vs 12%), more hypotension (11% vs 7%), more worsening renal function (10% vs 7%), and more hyperkalemia (6% vs 4%), but reported less cough (11% vs 13%) and had less hypokalemia (1% vs 3%).

There were no significant subgroup interactions for the primary outcome.

Conclusion: In patients with systolic heart failure, high dose ACE inhibition did not significantly reduce mortality compared to low-dose but it led to significantly less hospitalizations. In this trial of 3,164 patients and with a median follow up of 46 months, there were 578 less hospitalizations in the high dose group.

Based on these results, we recommend up-titrating ACEi and use higher doses if tolerated. Although, side effects were more common in the high dose group, these can generally be managed with reducing the dose in the outpatient settings.