Intracoronary electrocardiogram ST-segment elevation in patients with non-ST-segment elevation myocardial infarction and its association with culprit lesion location and myocardial injury

Algorithm for real-time analysis of intracoronary electrocardiogram

Introduction

Since its first implementation in 1985, intracoronary (ic) electrocardiogram (ECG) has shown ample evidence for its diagnostic value given the higher sensitivity for myocardial ischemia detection in comparison to surface ECG. However, a lack of online systems to quantitatively analyze icECG in real-time prevents its routine use. The present study aimed to develop and validate an autonomous icECG analyzing algorithm.

Materials and methods

This is a retrospective observational study in 100 patients with chronic coronary syndrome. From each patient, a non-ischemic as well as ischemic icECG at the end of a 1-min proximal coronary balloon occlusion was available. An ECG expert as well as the newly developed algorithm for autonomous icECG analysis measured the icECG ST-segment shift in mV for each icECG tracing.

Results

Intraclass correlation coefficient (ICC) demonstrated low variability between the two methods (ICC = 0.968). Using the time point of icECG recording as allocation reference for absent or present myocardial ischemia, ROC-analysis for ischemia detection by the manually determined icECG ST-segment shift showed an area under the curve (AUC) of 0.968 ± 0.021 (p < 0.0001). AUC for the algorithm analysis was 0.967 ± 0.023 (p < 0.0001; p = 0.925 for the difference between the ROC curve AUCs). Time to complete analysis was below 1,000 ms for the autonomous icECG analysis and above 5 min for manual analysis.

Conclusion

A newly developed autonomous icECG analysing algorithm detects myocardial ischemia with equal accuracy as manual ST-segment shift assessment. The algorithm provides the technical fundament for an analysing system to quantitatively obtain icECG in real-time.

Synthesized 18-Lead Electrocardiogram in Diagnosing Posteriorstemi-Equivalentacute Coronary Syndrome in Patients with NSTEMI

Objective. To assess the clinical utility of synthesized V7–V9 ST-segment elevation (sV7-9 STE) in patients with 12-lead-electrocardiogram (ECG)-based non-STE myocardial infarction (NSTEMI) in diagnosing left circumflex artery (LCx) STEMI-equivalent acute coronary syndrome (ACS). Background. The 12-lead-ECG is insufficient for diagnosing patients with ACS, especially those with an LCx culprit. Methods. We retrospectively examined 219 patients with NSTEMI who underwent synthesized 18-lead ECG acquisition on admission and urgent catheterization. Associations between baseline variables, including sV7-9 STE and LCx STEMI-equivalent ACS, were analyzed using logistic regression models and receiver operating characteristics. LCx-culprit ACS was defined as thrombolysis in myocardial infarction (TIMI) 0–1 flow. The association between sV7-9 STE and myocardial damage was also assessed. Results. The mean (SD) age of the population was 68.8 (12.0) years, and 81.7% were men. LCx-culprit NSTEMI occurred in 58 (26.5%) patients and 15 (6.8%) were LCx STEMI-equivalent. SV7-9 STE was observed in 16 patients (7.9%). SV7-9 STE was the sole significant predictor of LCx STEMI-equivalent ACS with an odds ratio of 19.0 (95% CI: 5.6–63.9, $p<0.001$ ), area under the curve of 0.71 (95% CI: 0.58–0.84), sensitivity of 46.7%, and specificity of 95.6%. After adjustment for confounders, sV7-9 STE was significantly associated with a 308% (95% CI: 78–834%) increase in peak high-sensitivity cardiac troponin I ( $p=0.001$ ). Conclusions. SV7-9 STE had sole preprocedural diagnostic utility in detecting LCx STEMI-equivalent ACS with greater myocardial damage among patients with 12 ECG-based NSTEMI. The use of synthesized extra leads on admission may help identify patients with NSTEMI requiring primary revascularization.

The stability of flow velocity and intracoronary resistance in the intracoronary electrocardiogram-triggered pressure ratio

Assessment of coronary artery lesions using the fractional flow reserve and instantaneous flow reserve (iFR) measurements has been found to reduce the incidence of further cardiovascular events. Here, we investigated differences in terms of coronary flow velocity and resistance within the analysis interval between the iFR and the intracoronary electrocardiogram (IC-ECG)-triggered distal/aortic pressure (Pd/Pa) ratio (ICE-T). We enrolled 23 consecutive patients (n = 33 stenoses) who required coronary flow measurements. ICE-T was defined as the average Pd/Pa ratio in the period corresponding to the isoelectric line of the IC-ECG. We compared the index value, flow velocity, and intracoronary resistance during the analysis intervals of the iFR and the ICE-T, both at rest and under hyperemia. ICE-T values and ICE-T intracoronary resistance were both found to be significantly lower, whereas flow velocity was significantly higher than those of the iFR at both rest and under hyperemia (P < 0.001), and all fluctuations in ICE-T values were also significantly smaller than those in the iFR. In conclusion, the ICE-T appears theoretically superior to pressure-dependent indices for analyzing phases with low and stable resistance, without an increase in invasiveness.

Functional assessment of myocardial ischaemia by intracoronary ECG

Introduction

In patients with chronic coronary syndrome, percutaneous coronary intervention targets haemodynamically significant stenoses, that is, those thought to cause ischaemia. Intracoronary ECG (icECG) detects ischaemia directly where it occurs. Thus, the goal of this study was to test the accuracy of icECG during pharmacological inotropic stress to determine functional coronary lesion severity in comparison to the structural parameter of quantitative angiographic per cent diameter stenosis (%S), as well as to the haemodynamic indices of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR).

Method

The primary study endpoint of this prospective trial was the maximal change in icECG ST-segment shift during pharmacological inotropic stress induced by dobutamine plus atropine obtained within 1 min after reaching maximal heart rate(=220 - age). IcECG was acquired by attaching an alligator clamp to the angioplasty guidewire positioned downstream of the stenosis. For the pressure-derived stenosis severity ratios, coronary perfusion pressure and simultaneous aortic pressure were continuously recorded.

Results

There was a direct linear relation between icECG ST-segment shift and %S: icECG=−0.8+0.03*%S (r²=0.164; p<0.0001). There were inverse linear correlations between FFR and %S: FFR=1.1–6.1*10–3*%S (r²=0.494; p<0.0001), and between iFR and %S: iFR=1.27–8.6*10–3*%S (r²=0.461; p<0.0001). Using a %S-threshold of ≥50% as the reference for structural stenosis relevance, receiver operating characteristics-analysis of absolute icECG ST-segment shift during hyperemia showed an area under the curve (AUC) of 0.678±0.054 (p=0.002; sensitivity=85%, specificity=50% at 0.34 mV). AUC for FFR was 0.854±0.037 (p<0.0001; sensitivity=64%, specificity=96% at 0.78), and for iFR it was 0.816±0.043 (p<0.0001;sensitivity=62%, specificity=96% at 0.83).

Conclusions

Hyperaemic icECG ST-segment shift detects structurally relevant coronary stenotic lesions with high sensitivity, while they are identified highly specific by FFR and iFR.

Diagnostic Performance and Pressure Stability of a Novel Myocardial Ischemic Diagnostic Index - The Intracoronary-Electrocardiogram-Triggered Distal Pressure/Aortic Pressure Ratio

Background: We hypothesized that the intracoronary-electrocardiogram (IC-ECG)-based pressure index would be more stable and precise than the instantaneous flow reserve (iFR). We investigated the usefulness of the IC-ECG-based pressure index for diagnosing myocardial ischemia. Methods and Results: Thirty-seven consecutive patients with coronary stenosis requiring physiological assessment were enrolled in the study. iFR was measured at rest and under hyperemia in 51 and 40 lesions, respectively. The IC-ECG-triggered distal pressure (Pd)/aortic pressure (Pa) ratio (ICE-T) was defined as the mean Pd/Pa ratio in the period corresponding to the isoelectric line. The ICE-T was significantly lower than the iFR both at rest and during hyperemia (P<0.00001 for both). Fluctuations in the ICE-T pressure parameters (Pd/Pa, Pa, and Pd) were significantly smaller than those of iFR both at rest and during hyperemia. The diagnostic accuracy of predicting a fractional flow reserve (FFR) ≤0.80 of the ICE-T at rest was significantly higher than that of iFR (P=0.008). Receiver operating characteristic curve analyses showed that the ICE-T predicts FFR ≤0.80 more accurately than the iFR (area under curve 0.897 vs. 0.810 for ICE-T and iFR, respectively). Conclusions: We identified the period in the IC-ECG in which resting Pd/Pa was low and constant. The IC-ECG-based algorithm may improve the accuracy of diagnosing myocardial ischemia, without increasing invasiveness, compared with pressure-dependent indices.

Intracoronary electrocardiogram during alcohol septal ablation for hypertrophic obstructive cardiomyopathy predicts myocardial injury size

Alcohol septal ablation (ASA) has been used widely to treat patients with hypertrophic obstructive cardiomyopathy (HOCM). During the routine ASA procedure, it is difficult to detect the septal injury in real-time. The aim of the present study is to assess myocardial injury during ASA by recording intracoronary electrocardiogram (IC-ECG). From 2012 to 2015, 31 HOCM patients were treated with ASA, and IC-ECG was recorded in 21 patients successfully before and after ethanol injection. The elevation of ST-segment on IC-ECG after ethanol injection was expressed as its ratio to the level before injection or the absolute increasing value. Blood samples were collected before and after ASA for measuring changes in cardiac biomarkers. The ratio value of ST-segment elevation was positively correlated with both the amount of ethanol injected (r = 0.645, P = 0.001) and the myocardial injury size (creatine kinase-MB area under the curve (AUC) of CK-MB) (r = 0.466, P = 0.017). The absolute increment of ST-segment was also positively associated with both the amount of ethanol (r = 0.665, P = 0.001) and AUC of CK-MB (0.685, P = 0.001). However, there was no statistical correlation between the reduction of left ventricular outflow tract gradient and ST-segment elevation. Additionally no severe ASA procedure-related complications were observed in our patients. In conclusion, myocardial injury induced by ethanol injection can be assessed immediately by ST-segment elevation on IC-ECG. This study is the first to show that IC-ECG is a useful method for predicting myocardial injury during ASA in real-time.

ST-segment elevation on intracoronary electrocardiogram after percutaneous coronary intervention is associated with worse outcome in patients with non-ST-segment elevation myocardial infarction

OBJECTIVES

We sought to examine whether intracoronary electrocardiogram (IC-ECG) assessment in patients with non-ST-segment elevation myocardial infarction (NSTEMI) can predict cardiac outcomes.

BACKGROUND

There has been no data correlating myocardial damage and cardiac events with an IC-ECG ST-segment change after percutaneous coronary intervention (PCI) in NSTEMI patients.

METHODS

We examined 111 NSTEMI patients undergoing PCI with an IC-ECG recording. IC-ECG ST-segment elevation (STE) was defined as >0.1 mV in the risk area, located by placing the guidewire distal to the culprit lesion. Clinical characteristics and in-hospital and long-term follow-up adverse cardiac event rates were compared between IC-ECG STE and non-IC-ECG STE groups at the completion of PCI.

RESULTS

IC-ECG STE was observed in 36 patients (32.4%) immediately after PCI. Peak cardiac biomarkers were significantly elevated in patients with IC-ECG STE versus those without (cardiac troponin I 31.9 ng/mL (18.0-104.5) vs. 8.2 ng/mL (1.8-21.4); P < 0.001). At a median follow-up of 35 months, the cardiac event free rate was significantly worse in patients with IC-ECG STE than in those without (long-rank test χ(2) = 10.9; P = 0.001). Cox proportional hazards analysis showed IC-ECG STE (hazard ratio, 2.54; 95% confidence interval [CI], 1.38-4.70; P = 0.003) was an independent predictors of cardiac events.

CONCLUSIONS

The present study suggests that presence of IC-ECG STE might help identify high-risk NSTEMI patients with greater myocardial injury leading to adverse cardiac events.