NOVEL-APPROACH TO THE INTERPRETATION OF LONG-TERM DETERIORATION IN EJECTION FRACTION IN INDIVIDUAL PATIENTS WITH CORONARY-ARTERY DISEASE

Objective-The long-term predictability of left ventricular ejection fr action (LVEF) measurements was evaluated with particular emphasis on t he assessment of deterioration in individual patients whose coronary a rtery disease was initially treated medically. Design-Prospective pilo t study. Setting-Regional cardiac centre. Patients-60 minimally sympto matic patients with coronary artery disease who, after arteriography, were initially treated medically. Intervention-Measurement of LVEF by first pass exercise radionuclide ventriculography at baseline and six months later without interruption of usual anti-ischaemic medication. Baseline and six-month studies were analysed independently of each oth er. Main outcome measure-Based on 51 patients who remained event free, 95% prediction intervals were derived for prognostic LVEF indices to suggest the minimum change from baseline that might be considered clin ically important in the individual patient, alerting clinicians to the need for closer review. Results-At six-month ventriculography, 22 pat ients showed apparent deterioration in exercise LVEF or the change in LVEF with exercise (DELTALVEF). Only two patients had six-month values below the lower limit of 95% prediction intervals, compared with 15 w hen 95% group confidence intervals (z = 3.33, p < 0.001) were used. Wh en DELTALVEF = 0 at baseline, the lower limit of 95% prediction interv als allowed for an exercise induced fall at six months of less-than-or -equal-to 13%. For a baseline exercise LVEF of 50% (just normal), the lower limit of 95% prediction intervals was 38%-that is, the exercise LVEF could be measured as low as 38% greater-than-or-equal-to six mont hs later without necessarily indicating or missing true deterioration. Conclusion-In the follow up of minimally symptomatic patients with co ronary artery disease, serial long-term changes, in particular ''deter ioration,'' in prognostic LVEF indices may be interpreted more meaning fully with reference to 95% prediction intervals.