\"Biological clock\" related to heart attack

U.S. researchers on Wednesday said they had found Ventricular arrhythmia occurs most frequently after waking in the morning, the first link between the risk of sudden heart attack and circadian rhythm. The discovery is the first molecular proof that the \"biological clock\" is linked to a type of sudden, fatal heart attack. Reporting in the journal Nature, scientists found that a protein called Klf15 is a circadian controller, which is lacking among some patients with heart failure. The team spotted the mice, which are genetically engineered to either lack Klf15 or make the protein excessively, had a much higher risk of arrythmias compared to normal counterparts. Scientists found the mice were at risk for developing the arrhythmia if there was too much Klf15 or none. Researchers also believed that Klf15 controls another protein, KChIP2, which affects electrical current that flows through heart muscle cells called cardiac myocytes.