Detection and quantification of embolic particles during percutaneous coronary intervention to stable plaque: It correlates to coronary flow dynamics and myocardial damage

Pacing Postconditioning: Recent Insights of Mechanism of Action and Probable Future Clinical Application

Ischemic heart disease, also known as coronary heart disease or coronary artery disease, accounts for >50% of cardiovascular events and is a leading cause worldwide of morbidity and mortality. Hypoperfusion of the heart is the major cause of injury in ischemic heart disease, as it results in the death of cardiomyoctes due to a lack of oxygen and energy. This injury ultimately leads to a dead area in the heart called infarcted area or myocardial infarction. The formation of myocardial infarction leads to a lengthy process of remodeling which causes many changes in the architecture and the electrophysiology of the heart. These changes may eventually lead to death due to arrhythmia or heart failure. Tremendous efforts have been made over the last decades to decrease the burden of ischemic reperfusion (I/R) injury. The first salvage to the ischemic heart is reperfusion; however, this procedure is associated with a subsequent reperfusion injury. In the 1980s, a method known as preconditioning was introduced and showed great potential in combating ischemic heart disease, but this technique is limited by the difficulty of its translation to the clinic as it requires the anticipation of an occurrence of ischemic heart disease. Not long after, a new method, postconditioning, was introduced. This method showed great success, and several studies were performed to investigate its signaling cascades and the possibility of its translation to the clinic. Thereafter, several trials were made, and many methods of postconditioning were developed. One of these is intermittent dyssynchrony, pacing postconditioning (PPC), of the heart, which involves brief episodes of electrical pacing. PPC afforded a pronounced protection to the heart against I/R injury, similar to that afforded by pre- and postconditioning.

Effect of embolic particles during coronary interventional procedures on regional wall motion in patients with stable angina pectoris

Microembolization during percutaneous coronary intervention (PCI) causes minor myocardial injury, and a Doppler guidewire can detect embolic particles as high-intensity transient signals (HITS). The present study investigated the effect of microembolization during PCI on regional wall motion using a Doppler guidewire and myocardial strain analysis. We performed PCI to the left anterior descending coronary artery in 25 patients (18 men and 7 women, 68 ± 8 years old) with stable angina pectoris. Coronary flow spectrums were obtained with a Doppler guidewire to count the total number of HITS throughout the PCI procedures. On the days before and after PCI, we recorded echocardiography and measured the longitudinal peak systolic strain, peak strain rate, and early diastolic strain rate in the left anterior descending territory using a 2-dimensional speckle tracking method. PCI was successfully performed, and 10 ± 6 HITS (range 0 to 22, median 9) were recognized during PCI. The echocardiographic study showed no visible wall motion abnormalities in the left anterior descending territory either after or before PCI. In cases in which the total number of HITS was ≥10, the peak systolic strain, peak strain rate, and early diastolic strain rate worsened on the day after PCI compared with those on the day before PCI (p <0.01). The rates of change in peak systolic strain and early diastolic strain rate, defined as the ratios of those parameters after PCI to those before PCI, had modest to strong inverse correlations with the total number of HITS (R(2) = 0.35 and R(2) = 0.46, respectively). In conclusion, periprocedural microembolization during PCI reduces subclinical cardiac function in patients with stable angina pectoris.

Deep echo attenuation without calcification increases the risk of periprocedural myonecrosis after elective percutaneous coronary intervention in patients with coronary artery disease

OBJECTIVE

To investigate the clinical factors, including intravascular ultrasound (IVUS) findings, associated with percutaneous coronary intervention (PCI)-related periprocedural myonecrosis (PM) in patients with stable coronary artery disease (CAD).

METHODS

The study included 46 patients (mean age 65±2 y, 37 men) with stable CAD who underwent elective PCI using IVUS and a Doppler flow guidewire. In addition to routine IVUS measurements, the presence of deep echo attenuation (DEA) without calcification was assessed. The sum of all high-intensity transient signals (HITS) after a balloon deflation procedure was calculated using a Doppler flow guidewire. PM was defined as an elevation in troponin T to >0.03 ng/mL 24-hour after PCI. Patients were divided into 2 groups on the basis of the presence or absence of PM.

RESULTS

PM was identified in 17 patients (37%). Estimated glomerular filtration ratio was lower in the PM group (p=0.021). Target vessel distribution was different between the groups (p=0.004). Positive remodeling and DEA, as observed on IVUS, were more common in the PM group (p=0.03 and p<0.0001, respectively). The total number of HITS was higher in the PM group (p=0.003). Logistic regression analysis demonstrated that the presence of DEA (p=0.003) was the sole factor associated with the occurrence of PM.

CONCLUSION

These results demonstrated that DEA is an important factor associated with PM in patients who underwent an elective PCI. Therefore, IVUS to determine the presence of DEA should be performed before PCI.

Lack of consensus in biomarker measurement to diagnose PCI-related myocardial infarction

OBJECTIVE

To evaluate if biomarker sampling in PCI has adhered to the 2 000 consensus document for the diagnosis of procedure-related myocardial infarction (MI).

DESIGN

Firstly, a review of relevant papers from 2000 to September 2007 was done. Secondly, in October 2007, a questionnaire addressing biomarker sampling in routine PCI was sent to Danish PCI centres.

RESULTS

Fourteen papers fulfilled the selection criteria. In six studies serial sampling according to the consensus document had been done. Biomarker measuring before PCI was not performed in four studies. All centres answered the questionnaire. In none of six centres the proposed 3-sample testing of biomarkers had been followed. A pre-PCI sample was taken in one centre. In approximately half of the centres biomarkers were only measured on clinical indication.

CONCLUSION

Biomarker sampling for procedure-related MI according to the 2 000 consensus document has not been universally adapted. In order to avoid hampering of epidemiologic data and the comparison of future clinical trials it is proposed that the 2007 MI re-definition consensus document will be rapidly and universally accepted.

Automatic Detection of Microemboli During Percutaneous Coronary Interventions

The objective of this study was to develop an analysis method for the automatic detection of intracoronary microemboli triggered high intensity signals (HITS) during percutaneous coronary interventions (PCI). The recorded ultrasonic Doppler velocity spectra from an intracoronary ultrasonic guide-wire were decomposed into 13 wavelet scales applying the continuous wavelet transform. From 7 wavelet scales which were most suitable for a differentiation between HITS and pulsatile flow, envelopes were calculated and combined to improve the HITS-to-background noise ratio. For different intensity thresholds the resulting number of HITS was automatically counted and compared with the number estimated by experienced observers. In a first validation trial HITS were detected within a simplified in vitro model with a sensitivity of 89.2% and a positive predictive value of 87.6%. In a following clinical study 211 HITS from 18 patients during PCI were counted manually by the observers. With the developed wavelet-based method 189 HITS were correctly detected (sensitivity of 89.6%, positive predictive value of 85.5%). The introduced new method automatically detects intracoronary HITS for the first time with a reliable accuracy. This may support further studies evaluating the incidence and consequences of coronary microembolization during coronary interventions.