Boston Scientific Corp., the second- biggest cardiac-device maker, fell in early trading after fourth-quarter earnings plummeted 55 percent. Boston Scientific declined 3.6 percent to $5.87 at 8:30 a.m. Net income dropped to $107 million, or 7 cents a share, from $236 million, or 15 cents a share, a year earlier, the Natick, Massachusetts-based company said today in a statement. Demand for defibrillators to restart a stopped heart and pacemakers to ensure a steady rhythm, two of Boston Scientific’s biggest products, continued to fall in the fourth quarter after peaking in 2009. The company won U.S. approval in November for the Promus Element heart stent, its own higher-profit version of a device it previously licensed from Abbott Laboratories.