European Central Bank officials at their last meeting saw "grounds for cautious optimism" about the economy as their stimulus measures take hold.

A summary of the bank's April 21 meeting released Thursday indicates the ECB is now focused on implementing measures that have been decided but are still in the pipeline — rather than readying new ones.

The summary said "patience was needed" for stimulus to fully unfold as it prepares to start corporate bond purchases in June. Those would pump more newly printed money into the economy to raise dangerously low inflation and boost growth.

The board also decided to publicly remind German skeptics critical of its stimulus measures that the bank is politically independent.

The eurozone economy grew 0.6 percent in the first quarter amid a modest recovery.