On the cover: Synchronous emergence of Ca²⁺ waves (dotted lines in x-t images) in individual cells accompanies a single event of triggered activity (red circle), followed by Ca²⁺ oscillation (green trace) with concomitant membrane fluctuation (red trace) showing a gradual reduction in amplitude. Fluorescence intensities of fluo4/AM and RH237 were measured in subepicardial ventricular myocytes of Langendorff-perfused rat heart with dual-view, rapid-scanning confocal microscopy. The triggered activity was induced by 2-Hz pacing under low-K⁺ (2.4 mmol/L) perfusion and isoproterenol (3 nmol/L) at 25°C. See related article, page 509.