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Prognostic value of predischarge exercise testing, ejection fraction, and ventricular ectopic activity in acute
R S Khattar1, S K Basu, U Raval
1Department of Cardiology, Northwick Park Hospital, Harrow, United Kingdom.
Insights
Left ventricular function and exercise time are key predictors of cardiac events after myocardial infarction. Ventricular ectopic activity alone does not provide significant prognostic information.
Area of Science:
- Cardiology
- Internal Medicine
- Clinical Research
Background:
- Prognostic factors for left ventricular function, ischemia, and arrhythmias post-thrombolysis are unclear.
- Assessing the relative importance of these parameters is crucial for patient management.
Purpose of the Study:
- To determine the prognostic value of predischarge treadmill exercise testing, radionuclide ventriculography, and ambulatory electrocardiographic monitoring.
- To identify key predictors of cardiac events after acute myocardial infarction treated with thrombolysis.
Main Methods:
- 112 patients with acute myocardial infarction treated with thrombolysis were studied.
- Predischarge treadmill exercise testing, radionuclide ventriculography, and ambulatory ECG monitoring were performed.
- Cardiac events were tracked over an 18-month follow-up period.
Main Results:
- Univariate analysis identified ejection fraction, exercise time, and ventricular ectopic count (> or = 10/hour) as predictors.
- Multivariate analysis confirmed independent prognostic value for ejection fraction and exercise time.
- Ventricular ectopic activity did not independently predict events but showed value when combined with ejection fraction or exercise time.
Conclusions:
- Ejection fraction and exercise time are independent predictors of cardiac events after thrombolysis for myocardial infarction.
- These parameters can predict heart failure but not recurrent ischemic events.
- Ventricular ectopic activity has limited independent prognostic value in this context.
Abstract:
The relative importance of prognostic parameters that delineate left ventricular function, myocardial ischemia, and arrhythmogenic potential after thrombolytic therapy is not clear. This study investigated 112 patients with acute myocardial infarction who were treated with thrombolysis to determine the relative prognostic value of predischarge treadmill exercise testing, radionuclide ventriculography, and ambulatory electrocardiographic monitoring for ventricular ectopic activity. During a mean follow-up period of 18 months (range 6 to 30), 42 first cardiac events were recorded, consisting of 3 deaths, 6 reinfarctions, 16 bouts of unstable angina, 16 episodes of heart failure, and 1 arrhythmic event. Univariate analysis revealed ejection fraction, exercise time, and ventricular ectopic count of > or = 10/hour to be predictive of future cardiac events. Subsequent multivariate analysis showed ejection fraction (p <0.001) and exercise time (p=0.002 to have independent prognostic value, but ventricular ectopic activity did not provide additional information. Ventricular ectopic count > or = 10/hour was additionally predictive only when combined with either ejection fraction (R2=5.4%) or exercise time (R2=2.9%). Event-free survival analysis revealed hazard ratios for ejection fraction <40% and exercise time <7 minutes of 3.63 (p=0.001) and 2.16 (p=0.01), respectively. Although ejection fraction and exercise time were able to predict future episodes of heart failure, neither could adequately identify patients at risk of recurrent ischemic events.