At least 2.5 million Greeks, almost a quarter of the population, have high blood pressure – the main cause of heart attacks and strokes – but few try to improve their health, an international cardiology conference in Thessaloniki heard yesterday. Around 5,000 heart by-pass operations and 10,000 other types of heart surgery are conducted every year in Greece, according to Athens University professor Grigorios Vyssoulis. But most patients fail to change their ways even after surgery. Half of smokers – who account for 75 percent of by-pass patients – do not kick the habit after leaving the hospital, according to Ioannina University cardiologist Athanassios Papathanassiou. Also, only half of patients with high cholesterol take a course of drugs to tackle their problem after surgery, he said. The easiest way to avert high blood pressure is to cut down on salt, Vyssoulis said, adding that those with a serious problem should be prescribed hypertension drugs. This can reduce the risk of strokes by up to 40 percent and of heart attacks by up to 25 percent, he said.