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Optimising the Dichotomy Limit for Left Ventricular Ejection Fraction in Selecting Patients For Defibrillator Therapy After Myocardial Infarction
  1. Yee Guan Yap (ygyap{at}aol.com)
  1. University Putra Malaysia, Malaysia
    1. Trinh Duong
    1. St. George's Hospital Medical School, London, United Kingdom
      1. Martin Bland
      1. St. George's Hospital Medical School, London, United Kingdom
        1. Marek Malik
        1. St. George's Hospital Medical School, London, United Kingdom
          1. Christian Torp-Pedersen
          1. Gentofte University Hospital, Hellerup, Denmark
            1. Lars Kober
            1. The National Hospital, Copenhagen, Denmark
              1. Mark M Gallagher
              1. St. George's Hospital Medical School, London, United Kingdom
                1. A John Camm
                1. St. George's Hospital Medical School, London, United Kingdom

                  Abstract

                  Background The selection of patients for prophylactic ICD therapy after myocardial infarction (MI) remains controversial. We sought to determine the optimal LVEF dichotomy limit for ICD therapy in patients with a history of MI.

                  Methods and results Data from the placebo arms of 4 randomized trials were pooled to create a cohort of 2828 patients (2206 M, age: 65 ± 11) with reduced left ventricular function after MI. The median left ventricular ejection fraction (LVEF) was 33% (range: 6 - 40%). LVEF significantly predicted mortality. Each 10% reduction in LVEF below 40% conferred a 42% increase in all-cause mortality, a 39% increase in arrhythmic cardiac mortality and 49% increase in non-arrhythmic cardiac mortality over the 2-year period of follow up (p < 0.001 for all modes of mortality). As the LVEF progressively decreased from </= 40% to </= 10%, the data show a "U" shaped relationship between the dichotomy limit for LVEF used and the number of patients that must be treated to prevent 1 arrhythmic death in 2 years. At LVEF of 16% - 20%, more patients are likely to die from arrhythmic than non-arrhythmic cardiac deaths. However, the total number of deaths substantially reduced with lower LVEF.

                  Conclusion There is a trade-off between the sensitivity and positive predictive accuracy across a range of LVEF and no single dichotomy limit is completely satisfactory. In patients with LVEF </= 10%, ICD therapy was not beneficial as all patients in this subgroup died from non-arrhythmic causes. LVEF alone is not sufficient in selecting most high risk patients for primary ICD therapy and further risk stratification process is needed.

                  • acute myocardial infarction
                  • all-cause mortality
                  • arrhythmic cardiac mortality
                  • left ventricular ejection fraction
                  • non-arrhythmic cardiac mortality

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