Kjell Nikus

Electrocardiographic classification of acute coronary syndromes: a review by a committee of the International Society for Holter and Non-Invasive Electrocardiology.

The electrocardiogram (ECG) remains the most immediately accessible and widely used diagnostic tool for guiding emergency treatment strategies. The ECG recorded during acute myocardial ischemia is of diagnostic, therapeutic, and prognostic significance. In patients with myocardial ischemia as a result of decreased blood supply, the initial 12-lead ECG typically shows (1) predominant ST-segment elevation (STE) as part of STE acute coronary syndrome (STE-ACS), or (2) no predominant STE, that is, non-STE ACS (NSTE-ACS). Patients with predominant STE are classified as having either aborted myocardial infarction (MI) or ST-elevation MI (STEMI) based on the absence or presence of biomarkers of myocardial necrosis. The MI may be aborted either by spontaneous or therapeutic reperfusion of the ischemic myocardium before development of myocardial cell necrosis. NSTE-ACS patients are classified as having either unstable angina or NSTE-MI, based also on the absence or presence of biomarkers of mycardial necrosis. The information obtained from the 12-lead ECG at presentation should be complemented by repeated ECGs especially during symptoms indicative of ischemia and, if applicable, by comparing the findings with reference ECGs. Also, continuous ECG recording in a coronary care setting, including the comparison of ECGs with and without pain, adds to the information gained at patient presentation. In this article, mechanisms of ischemic ECG changes and the ECG patterns recorded in both STE-ACS and NSTE-ACS are described. ECG patterns of NSTE-ACS, which include ST depression, negative T wave, and even normal ECG, need to be better defined in future studies to correlate them with the severity and extent of ischemia and to explore to what extent they are explained by acute active ischemia or represent consequences of ischemia. One of the aims of this article is to propose a classification of the ECG patterns encountered in different clinical scenarios of ACS. How these patterns will aid in guiding the diagnostic and therapeutic process is discussed.

Enhanced Predictive Power of Quantitative TWA during Routine Exercise Testing in the Finnish Cardiovascular Study

Introduction: We examined whether quantification of T‐wave alternans (TWA) enhances this parameters capacity to evaluate the risk for total and cardiovascular mortality and sudden cardiac death (SCD).

Post-exercise assessment of cardiac repolarization alternans in patients with coronary artery disease using the modified moving average method.

OBJECTIVES We sought to evaluate the utility of T-wave alternans (TWA) assessment in the immediate post-exercise period to identify and validate cutpoints for the modified moving average (MMA) assessment method. BACKGROUND The presence of TWA is associated with an increased risk of cardiovascular death (CVD). The immediate post-exercise period, where increased physiologic stress and minimal surface artifact coexist, appears ideal to implement the MMA method. METHODS A test (n = 322) and validation cohort (n = 681) provided 1,003 patients with coronary artery disease (CAD). We assessed TWA immediately after exercise. The outcomes, CVD and mortality, were adjudicated independent of the TWA results. RESULTS During 48 months of follow-up 85 deaths, 54 categorized as CVD (64%), were observed. A linear relationship between the magnitude of TWA and the risk of CVD was identified. As a continuous measure TWA voltage was equivalent to ejection fraction in predicting the risk of CVD. To facilitate clinical application, a sensitive, modest predictive accuracy (20 microV) and a specific, greater predictive accuracy MMA cutpoint (60 microV) were identified and validated. Each cutpoint was associated with a 2.5-fold greater risk of CVD, independent of other important variables, including ejection fraction. CONCLUSIONS Post-exercise assessment of TWA using the MMA method is a strong, independent predictor of risk in patients with CAD. The 20-microV cutpoint (87% sensitivity) appears to be most suitable in higher-risk patients, whereas the 60-microV cutpoint (95% specificity) appears more appropriate when TWA is used as a single screening test in those at lower risk. (Assessment of Noninvasive Methods to Identify Patients at Risk of Serious Arrhythmias After a Heart Attack; NCT00399503).

Combined assessment of heart rate recovery and T-wave alternans during routine exercise testing improves prediction of total and cardiovascular mortality: the Finnish Cardiovascular Study.

BACKGROUND Identification of individuals who are at risk for cardiovascular death remains a pressing public health challenge. Derangements in autonomic function acting upon an electrically unstable substrate are thought to be critical elements in triggering cardiovascular events. OBJECTIVE The purpose of this study was to analyze heart rate recovery (HRR) in combination with T-wave alternans (TWA) to improve risk assessment. METHODS The Finnish Cardiovascular Study (FINCAVAS) enrolled consecutive patients (N = 1,972 [1,254 men and 718 women], age 57 +/- 13 years [mean +/- SD]) with a clinically indicated exercise test using bicycle ergometer. TWA was analyzed continuously with the time-domain modified moving average method. Maximum TWA at heart rates <125 bpm was derived. RESULTS During 48 +/- 13 months of follow-up (mean +/- SD), 116 patients died; 55 deaths were cardiovascular. In multivariable Cox analysis after adjustment for common coronary risk factors, high exercise-based TWA (> or =60 microV) and low HRR (< or =18 bpm) yielded relative risks for all-cause mortality of 5.0 (95% confidence 2.1-12.1, P <.01) and for cardiovascular mortality of 12.3 (95% confidence interval 4.3-35.3, P <.01). High recovery-based TWA (> or =60 microV) and low HRR (< or =18 bpm) yielded relative risks for all-cause death of 6.1 (95% confidence interval 2.8-13.2, P <.01) and for cardiovascular mortality of 8.0 (95% confidence interval 2.9-22.0, P <.01). Prediction by HRR and TWA, both singly and in combination, exceeded that of standard cardiovascular risk factors. CONCLUSION Reduced HRR and heightened TWA powerfully predict risk for cardiovascular and all-cause death in a low-risk population. This novel approach could aid in screening of general populations during routine exercise protocols as well as improve insights into pathophysiology.

The Finnish Cardiovascular Study (FINCAVAS): characterising patients with high risk of cardiovascular morbidity and mortality

BackgroundThe purpose of the Finnish Cardiovascular Study (FINCAVAS) is to construct a risk profile – using genetic, haemodynamic and electrocardiographic (ECG) markers – of individuals at high risk of cardiovascular diseases, events and deaths.Methods and designAll patients scheduled for an exercise stress test at Tampere University Hospital and willing to participate have been and will be recruited between October 2001 and December 2007. The final number of participants is estimated to reach 5,000. Technically successful data on exercise tests using a bicycle ergometer have been collected of 2,212 patients (1,400 men and 812 women) by the end of 2004. In addition to repeated measurement of heart rate and blood pressure, digital high-resolution ECG at 500 Hz is recorded continuously during the entire exercise test, including the resting and recovery phases. About 20% of the patients are examined with coronary angiography. Genetic variations known or suspected to alter cardiovascular function or pathophysiology are analysed to elucidate the effects and interactions of these candidate genes, exercise and commonly used cardiovascular medications.DiscussionFINCAVAS compiles an extensive set of data on patient history, genetic variation, cardiovascular parameters, ECG markers as well as follow-up data on clinical events, hospitalisations and deaths. The data enables the development of new diagnostic and prognostic tools as well as assessments of the importance of existing markers.

Pregnancy‐associated plasma protein A: A biomarker in acute ST‐elevation myocardial infarction (STEMI)

Background. Elevated circulating levels of pregnancy‐associated plasma protein A (PAPP‐A), a novel marker of atherosclerotic plaque instability, are associated with increased risk of future cardiac events in patients with acute coronary syndromes (ACS). However, little is known of the kinetics or clinical significance of circulating PAPP‐A after plaque rupture in acute ST‐elevation myocardial infarction (STEMI). Aim. To evaluate the 48‐hour release of pregnancy‐associated plasma protein A (PAPP‐A) and its association with 12‐month outcome in patients with acute ST‐elevation myocardial infarction (STEMI). Methods. Sixty‐two consecutive STEMI patients were included (40 men and 22 women, median age 67.5 years (range 34–84)), of whom 54 (87.1%) received reperfusion therapy. PAPP‐A was measured at admission and 6–12, 24 and 48 hours thereafter. In 14 patients, samples were obtained also at 1, 2 and 4 hours. Results. There was an early peak of circulating PAPP‐A during the first 12 hours from symptom onset, followed by rapid normalization. A second, late PAPP‐A elevation was noticed in 20/62 patients (32.3%). Admission PAPP‐A >10.0 mIU/L (highest tertile) was associated (P = 0.049) with increased 12‐month risk of cardiovascular death or non‐fatal myocardial infarction. Moreover, the combination of failed early reperfusion together with late PAPP‐A elevation was strongly (7/13 versus 10/49 patients, P = 0.016) associated with adverse outcome. Admission PAPP‐A did not correlate with admission C‐reactive protein or cardiac troponin I. Conclusions. PAPP‐A is elevated early in STEMI and then declines rapidly, a pattern consistent with release from the ruptured plaque. The variability of PAPP‐A kinetics at 48 hours reflects the success of reperfusion. This study also shows that PAPP‐A may have prognostic value in STEMI.

Differentiating ST Elevation Myocardial Infarction and Nonischemic Causes of ST Elevation by Analyzing the Presenting Electrocardiogram

Guidelines recommend that patients with suggestive symptoms of myocardial ischemia and ST-segment elevation (STE) in > or =2 adjacent electrocardiographic leads should receive immediate reperfusion therapy. Novel strategies aimed to reduce door-to-balloon time, such as prehospital wireless electrocardiographic transmission, may be dependent on the interpretation accuracy of the electrocardiogram (ECG) readers. We assessed the ability of experienced electrocardiographers to differentiate among STE, acute STE myocardial infarction (STEMI), and nonischemic STE (NISTE). A total of 116 consecutive ECGs showing STE were studied. Fifteen experienced cardiologists were asked to decide, based on the ECG and assuming that the patient had compatible symptoms, whether they would send each patient for primary percutaneous coronary intervention (PPCI). If NISTE was chosen, the reader selected 1 or more 12 possible options to explain the choice. Of 116 patients, only 8 had STEMI. The percentage of ECGs for which PPCI was recommended for the patient by the individual readers varied widely (7.8% to 33%). There was no significant difference between the North American and Other Countries readers (p = 0.13). The sensitivity and specificity of the individual readers ranged from 50% to 100% (average 75%) and 73% to 97% (average 85%), respectively. There were broad inconsistencies among the readers in the chosen reasons used to classify NISTE. In conclusion, we found wide variations among experienced electrocardiographers in reading ECGs with STE and differentiating STEMI with need for PPCI from NISTE. There is a need to revise our current electrocardiographic criteria for differentiating STEMI from NISTE.

Electrocardiogram patterns in acute left main coronary artery occlusion

Acute coronary syndrome with subtotal occlusion of the left main coronary artery is rather frequently encountered in the catheterization laboratory, whereas survival to hospital admission of sudden total occlusion of the left main coronary artery is rare. The typical electrocardiographic (ECG) finding in cases with preserved flow through the left main is widespread ST-segment depression maximally in leads V4-V6 with inverted T waves and ST-segment elevation in lead aVR. In acute myocardial ischemia without (or with minor) myocardial necrosis, the ECG pattern is transient, whereas persistent ECG changes, usually without development of Q waves, are indicative of myocardial injury. In acute total left main occlusion, severe ischemia may be manifested in the ECG by life-threatening tachyarrhythmias, conduction disturbances, and ST-segment deviation. Because of the potential for life-saving therapeutic options by invasive therapy, the ECG markers of the serious condition should be recognized by the medical profession. Left main occlusion should be suspected in severely ill patients with widespread ST-segment depressions, especially in leads V4-V6 with inverted T waves or ST elevation involving the anterior precordial leads and the lateral extremity leads I and aVL. In addition, lead aVR ST elevation accompanied by either anterior ST elevation or widespread ST-segment depression may indicate left main occlusion.

Common pitfalls in the interpretation of electrocardiograms from patients with acute coronary syndromes with narrow QRS: a consensus report

Acute coronary syndromes (ACS) with narrow QRS are divided into 2 groups: ST-elevation ACS that requires emergency percutaneous coronary intervention, and non-ST elevation ACS. The classification of ACS into these 2 groups is not always straightforward. In this document, we discuss several electrocardiogram patterns of acute ischemia that are often misinterpreted. We suggest that any new recommendations or guidelines from the Scientific Societies should acknowledge these aspects of electrocardiogram interpretation by including appropriate diagnostic criteria that should prove helpful for the optimal management of patients with ACS.

Mortality of patients with acute coronary syndromes still remains high: A follow‐up study of 1188 consecutive patients admitted to a university hospital

Background. Based on randomized clinical trials, mortality of acute coronary syndrome (ACS) has been considered to be relatively low. The prognosis of clinical presentations of ACS in real‐life patient cohorts has not been well documented. Aim. The aim of this study was to evaluate actual clinical outcome across the whole spectrum of ACS in a series of unselected prospectively collected consecutive patients from a defined geographical region, all admitted to one university hospital. Methods. A total of 1188 patients with ST‐elevation myocardial infarction (STEMI), non‐ST‐elevation MI (NSTEMI) or unstable angina pectoris (UA) were included. Results. In‐hospital mortality was 9.6%, 13% and 2.6% (P<0.001) and mortality at a median follow‐up of 10 months 19%, 27% and 12% (P<0.001), for the three ACS categories, respectively. In multivariate Cox regression analysis age, diabetes mellitus type 1, diuretic use at admission, creatinine level, lower systolic blood pressure, STEMI and NSTEMI ACS category were associated with higher mortality during follow‐up. Conclusions. In an unselected patient cohort, short‐term mortality of MI patients, especially those classified as NSTEMI, still was high despite increasing use of proven treatment modalities.