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Use of ventricular premature complexes for risk stratification after acute myocardial infarction in the thrombolytic
D J Statters1, M Malik, S Redwood
1Department of Cardiological Sciences, St. George's Hospital Medical School, London, United Kingdom.
Insights
Ventricular premature complexes (VPCs) remain a significant predictor of cardiac events after acute myocardial infarction (AMI). Thrombolysis enhances the predictive accuracy of VPC frequency for mortality risk, requiring adjusted risk stratification.
Area of Science:
- Cardiology
- Clinical Electrophysiology
- Critical Care Medicine
Background:
- The predictive role of ventricular premature complexes (VPCs) for mortality after acute myocardial infarction (AMI) was established before thrombolytic therapy.
- Thrombolysis has altered the natural history of AMI, necessitating a reevaluation of established risk factors.
Purpose of the Study:
- To assess the prognostic significance of VPC frequency in patients after AMI, particularly in the context of early thrombolytic therapy.
- To compare the predictive accuracy of VPC frequency for adverse cardiac events between patients who received thrombolysis and those who did not.
Main Methods:
- A cohort of 680 patients post-AMI underwent 24-hour Holter monitoring 6-10 days after infarction in a drug-free state.
- Patients were followed for 1-8 years to record cardiac death, sudden death, and sustained ventricular tachycardia.
- VPC frequency was analyzed in relation to these outcomes, with subgroup analysis for patients who received thrombolytic therapy.
Main Results:
- Mean VPC frequency was significantly higher in patients who experienced cardiac death, sudden death, or arrhythmic events within the first year.
- VPC frequency remained a significant predictor regardless of thrombolysis status.
- The positive predictive accuracy of VPC frequency for adverse events was greater in patients who received thrombolysis compared to those who did not.
Conclusions:
- VPC frequency is a valuable prognostic marker after AMI, even with modern thrombolytic treatment.
- The predictive power of VPC frequency for adverse cardiac events is enhanced in patients treated with thrombolysis.
- Optimal risk stratification using VPC frequency requires adjusted thresholds for patients who have undergone thrombolytic therapy.
Abstract:
The independent predictive role of ventricular premature complex (VPC) frequency in the stratification of mortality risk after acute myocardial infarction (AMI) was established in the prethrombolytic era by extensive multicenter trials. Thrombolysis has lead to important changes in the natural history of patients after AMI, so that reassessment of established risk factors is now required. The prognostic significance of VPCs was assessed in 680 patients, of whom 379 received early thrombolytic therapy. All patients underwent 24-hour Holter monitoring in a drug-free state between 6 and 10 days after AMI. Patients were followed up for 1 to 8 years. During the first year of follow-up, cardiac death occurred in 33 patients, sudden death in 24, and sustained ventricular tachycardia in 20. Mean VPC frequency was significantly higher in patients who died of cardiac causes, in those who died suddenly, and in those with arrhythmic events during the first year of follow-up. This was also true when patients who did and did not undergo thrombolysis were considered separately. The positive predictive accuracy of VPC frequency in predicting adverse cardiac events was greater in patients who did than did not undergo thrombolysis. At a sensitivity level of 40%, the positive predictive accuracy for cardiac mortality and arrhythmic events for the group with thrombolysis was 19.4% and 25.8%, respectively, compared with 16% and 16% for those without thrombolysis. Moreover, the highest VPC frequency for the dichotomy of patients into high-and low-risk groups was 25 VPCs/hour for patients without thrombolysis. VPC frequency appears to be more highly predictive of prognosis after AMI in patients who have undergone thrombolysis than in those who have not, but the optimal frequency for dichotomy is higher in the former.