Prognostic significance of transient myocardial ischaemia after first acute myocardial infarction: five year follow up study

[Silent myocardial ischemia in acute coronary syndrome]

The given review considers the pathogenesis, diagnosis, and clinical significance of silent myocardial ischemia (SMI) in individual patient groups. It discusses the problem of SMI in acute coronary syndrome (ACS), the possible causes of SMI and the specific features of its diagnosis. It also indicates that there is a need for 12-lead ECG telemonitoring in intensive care unit patients with ACS to intraoperatively correct patient management and treatment policy.

Prevalence and prognostic implications of ST-segment deviations from ambulatory Holter monitoring after ST-segment elevation myocardial infarction treated with either fibrinolysis or primary percutaneous coronary intervention (a Danish Trial in Acute Myocardial Infarction-2 Substudy)

Ambulatory Holter monitoring has been shown to be useful in stratifying cardiovascular risk after acute myocardial infarction. However, it remains unclear whether ST-segment deviations might predict clinical outcomes in a population treated with primary percutaneous coronary intervention (PCI) compared with thrombolysis. Holter monitoring was initiated at discharge from ST-segment elevation myocardial infarction in 958 patients followed for 2,773 patient-years, randomized to immediate revascularization with either fibrinolysis (n=474) or PCI (n=484). The primary end point was all-cause mortality, and the secondary end point was a composite of death, reinfarction, and disabling stroke. The prevalences of ST-segment depression (STd) and ST-segment elevation (STe) were similar in patients treated with fibrinolysis or PCI (both p=NS). During follow-up, 58 patients died (primary PCI vs fibrinolysis hazard ratio 0.74, p=0.25). The secondary end point was reached in 113 patients (primary PCI vs fibrinolysis hazard ratio 0.66, p=0.03). In fibrinolysis-treated patients, mortality and the secondary end point were significantly higher in patients with STe (both end points p<0.001), an association that remained statistically significant after adjustment for age, gender, anterior infarction, beta-blocker treatment, left ventricular systolic function, and STd (p=0.03 and p=0.005, respectively). Significant associations were not observed for STd. In PCI-treated patients, there was no association between either STe or STd and outcome. In conclusion, immediate revascularization with PCI during STe myocardial infarction does not affect the subsequent prevalence of ST-segment deviation compared with fibrinolysis. However, although STe is an independent predictor of mortality and nonfatal major cardiovascular events in patients treated with fibrinolysis, it does not predict outcome after PCI, perhaps because of more complete revascularization.

Long-term value of exercise testing after acute myocardial infarction: influence of thrombolytic therapy

OBJECTIVES

To evaluate the long-term predictive value of exercise testing performed early after acute myocardial infarction (AMI) in patients receiving thrombolytic therapy.

DESIGN

Nonblinded prospective follow-up study.

SETTING

Cardiac rehabilitation unit in a 900-bed university hospital.

SUBJECTS

Four hundred forty-three patients allowed to perform exercise testing 3 weeks after AMI were followed for a median of 75 months; 183 received IV thrombolysis and 263 did not.

RESULTS

Cardiac death hazard ratios were significantly increased in the presence of reduced physical working capacity on exertion, left ventricular dysfunction, and > or = 1-mm (but < 2-mm) ST-segment depression on exertion. In the group receiving thrombolytic therapy, no patient with > or = 2-mm ST-segment depression on exercise died; this group was characterized by a high rate of revascularization, whereas the group with > or = 1-mm but < 2-mm ST-segment depression was not. No parameter related to clinical or exercise testing predicted recurrent infarction in the group receiving thrombolytic therapy. Among patients not receiving thrombolysis, cardiac death was significantly related to > or = 2-mm ST-segment depression on exertion, to reduced physical working capacity, and to the lack of revascularization during follow-up.

CONCLUSION

Exercise test-derived parameters have variable value in predicting long-term survival of patients performing exercise test after AMI depending on the following: (1) whether thrombolytic therapy was given or not; (2) the degree of ST-segment depression during exercise testing; and (3) the rate of revascularization.

Risk stratification after acute myocardial infarction in the reperfusion era

Historically, risk stratification for survivors of acute myocardial infarction (AMI) has centered on 3 principles: assessment of left ventricular function, detection of residual myocardial ischemia, and estimation of the risk for sudden cardiac death. Although these factors still have important prognostic implications for these patients, our ability to predict adverse cardiac events has significantly improved over the last several years. Recent studies have identified powerful predictors of adverse cardiac events available from the patient history, physical examination, initial electrocardiogram, and blood testing early in the evaluation of patients with AMI. Numerous studies performed in patients receiving early reperfusion therapy with either thrombolysis or primary angioplasty have emphasized the importance of a patent infarct related artery for long-term survival. The predictive value of a variety of noninvasive and invasive tests to predict myocardial electrical instability have been under active investigation in patients receiving early reperfusion therapy. The current understanding of the clinically important predictors of clinical outcomes in survivors of AMI is reviewed in this article.

Characteristics and prognostic importance of ST-segment elevation on Holter monitoring early after acute myocardial infarction

The correlation between episodes of ST-segment elevation on Holter monitoring, clinical characteristics, left ventricular function, exercise testing, and long-term prognosis was determined in 123 consecutive patients 55 +/- 8 years old (mean +/- SD) with a first acute myocardial infarction (AMI). During 36 hours of Holter recording 11 +/- 5 days after AMI, 11 patients (9%) had 91 episodes of ST-segment elevation (group 1), whereas 112 patients had no such episodes (group 2). Most episodes of ST-segment elevation occurred in leads with pathologic Q waves or small, indistinct R waves. Large, anterior Q-wave AMIs were more prevalent in group 1 than in group 2, and in-hospital heart failure also occurred more frequently in group 1 patients (82% vs 23%; p < 0.0005). Regional and global left ventricular function was reduced in group 1 compared with group 2: ejection fraction 33 +/- 11% vs 50 +/- 11% (p = 0.0001). All episodes of ST-segment elevation were asymptomatic and did not correlate with different indicators of myocardial ischemia. Indeed, exercise-induced ST-segment depression was more prevalent in group 2 than in group 1: 57 vs 18% (p < 0.035). Over a mean of 5 years (range 4 to 6) of follow-up, an association between episodes of ST-segment elevation on Holter monitoring and (1) cardiac death (Kaplan-Meier analysis; p < 0.005), and (2) cardiac death and nonfatal reinfarction (Kaplan-Meier analysis; p < 0.025) was found.(ABSTRACT TRUNCATED AT 250 WORDS)