Objective: To analyze the relationship between sudden death and death from arrhythmia and multiple risk factors in patients with non-ST elevation acute coronary syndromes in two years of follow-up in China.
Methods: This study was a part of an international multicentre registry-Organization to Assess Strategies for Ischemic Syndromes (OASIS). The patients admitted to the hospital with non-ST elevation acute coronary syndrome were enrolled. No particular intervention was given for the treatment. All patients had been followed-up for two years. The patients' clinical characteristics, therapeutic regimes and major events during hospitalization and two years' follow-up period were recorded by filling in Case Report Forms according to the protocol offered by Canadian Cardiovascular Collaboration. Cox regression model was used to analyze the association with the most common causes of death and multiple factors recorded.
Results: From April 1999 to December 2001, 2294 cases were enrolled in 38 hospitals in China nationwide. Among them 2188 patients two years follow-up was accomplished. The mean age of the patients was (62.8+/-8.1) years. Male gender was dominant (62.3%). The clinical diagnosis at admission was unstable angina in 88.5% of the patients and non Q-wave myocardial infarction(MI) in the remaining 11.5%. The mortality was 7.6% with total deaths of 174 by the end of 24-month follow up. The most common cause of death was severe arrhythmias or sudden death (92 cases, 52.9%). More than 70 factors were analyzed by Cox regression model in order to determine which were the predominant factors of death. Major risk factors that predisposed to death were: number of episodes of MI during follow-up period, re-MI within 24 hours during hospitalization, heart failure during hospitalization, previous history of MI, recurrent angina pectoris during hospitalization, the duration of hospitalization, and patient age. Protective factors that reduced the chance of death were: the frequency of using nitrate, frequency of taking anti-platelet medicine or beta-blocker during follow-up period.
Conclusion: In China, the most common cause of death in patients with non-ST elevation acute coronary syndromes is severe arrhythmias or sudden death, and it is related with the severity of coronary artery disease and the age of patients in majority of cases. Some factors that influence survival are similar to those established by previous evidence based medicine.