Postsystolic thickening detected by Doppler myocardial imaging: a marker of viability or ischemia in patients with myocardial infarction

Segmental myocardial viability by echocardiography at rest

BACKGROUND

Myocardial viability assessment adds value to the therapeutic decision-making of patients with ischemic heart disease. In this feasibility study, we investigated whether established echocardiographic measurements of post-systolic shortening (PSS), strain, strain rate and wall motion score (WMS) can discover viable myocardial segments. Our hypothesis is that non-viable myocardial segments are both akinetic and without PSS.

METHODS

The study population consisted of 26 examinations strictly selected by visible dysfunction. We assessed WMS, strain by speckle tracking and strain rate by tissue Doppler. The segments (16*26 = 416) were categorized into either normokinetic/hypokinetic or akinetic/dyskinetic and whether there was PSS. The reference method was the presence of scar with segmental percentage volume scar fraction >50%, detected by late gadolinium-enhanced cardiovascular magnetic resonance. Agreement with echocardiography was evaluated by Kappa coefficient.

RESULTS

WMS had Kappa coefficient 0.43 (sensitivity 99%, specificity 35%). Kappa coefficient of strain was 0.28 (sensitivity 98%, specificity 23%). By combining PSS in akinetic segments with WMS and strain, the Kappa coefficient was 0.06 and 0.08 respectively.

CONCLUSION

Segmental viability was best shown by the presence of systolic function. Post-systolic shortening adds no value to the assessment of segmental myocardial viability.

Myocardial Postsystolic Shortening and Early Systolic Lengthening: Current Status and Future Directions

The concept of paradoxical myocardial deformation, commonly referred to as postsystolic shortening and early systolic lengthening, was originally described in the 1970s when assessed by invasive cardiac methods, such as ventriculograms, in patients with ischemia and animal experimental models. Today, novel tissue-based imaging technology has revealed that these phenomena occur far more frequently than first described. This article defines these deformational patterns, summarizes current knowledge about their existence and highlights the clinical potential associated with their understanding.

New Ultrasound Technologies for Ischemic Heart Disease Assessment and Monitoring in Cardiac Rehabilitation

Owing to its ease of application, noninvasive nature, and safety, echocardiography is an essential imaging modality to assess cardiac function in patients affected by ischemic heart disease (IHD). Over the past few decades, we have witnessed a continuous series of evolutions in the ultrasound field that have led to the introduction of innovative echocardiographic modalities which allowed to better understand the morphofunctional abnormalities occurring in cardiovascular diseases. This article offers an overview of some of the newest echocardiographic modalities and their promising application in IHD diagnosis, risk stratification, management, and monitoring after cardiac rehabilitation.

Postsystolic Shortening by Speckle Tracking Echocardiography Is an Independent Predictor of Cardiovascular Events and Mortality in the General Population

Background

Postsystolic shortening (PSS) has been proposed as a novel marker of contractile dysfunction in the myocardium. Our objective was to assess the prognostic potential of PSS on cardiovascular events and death in the general population.

Methods and Results

The study design consisted of a prospective cohort study of 1296 low‐risk participants from the general population, who were examined by speckle tracking echocardiography. The primary end point was the composite of heart failure, myocardial infarction, and cardiovascular death, defined as major adverse cardiovascular events (MACEs). The secondary end point was all‐cause death. The postsystolic index (PSI) was defined as follows: [(maximum strain in cardiac cycle−peak systolic strain)/(maximum strain in cardiac cycle)]×100. PSS was regarded as present if PSI >20%. During a median follow‐up of 11 years, 149 participants (12%) were diagnosed as having MACEs and 236 participants (18%) died. Increasing number of walls with PSS predicted both end points, an association that persisted after adjustment for age, sex, estimated glomerular filtration rate, global longitudinal strain, hypertension, heart rate, left ventricular ejection fraction, LV mass index, pro‐B‐type natriuretic peptide, previous ischemic heart disease, systolic blood pressure, average peak early diastolic longitudinal mitral annular velocity (e′), ratio between peak transmitral early and late diastolic inflow velocity (E/A), and left atrial volume index: MACEs (hazard ratio, 1.35; 95% confidence interval, 1.09–1.67; P=0.006 per 1 increase in walls displaying PSS) and death (hazard ratio, 1.30; 95% confidence interval, 1.08–1.57; P=0.006 per 1 increase in walls displaying PSS). The strongest predictor of end points was ≥2 walls exhibiting PSS. The PSI also predicted increased risk of the end points, and the associations remained significant in multivariable models: MACEs (per 1% increase in PSI: hazard ratio, 1.18; 95% confidence interval, 1.02–1.36; P=0.024) and death (per 1% increase in PSI: hazard ratio, 1.18; 95% confidence interval, 1.05–1.33; P=0.005).

Conclusions

Presence of PSS in the general population provides independent and long‐term prognostic information on the occurrence of MACEs and death.

Presence of post-systolic shortening is an independent predictor of heart failure in patients following ST-segment elevation myocardial infarction

Following an ischemic event post systolic shortening (PSS) may occur. We investigated the association between PSS in patients with ST-segment elevation myocardial infarction (STEMI) following primary percutaneous coronary intervention (pPCI) and occurrence of cardiovascular events at follow-up. A total of 373 patients admitted with STEMI and treated with pPCI were prospectively included in the study cohort. All patients were examined by echocardiography a median of 2 days after admission (interquartile range, 1-3 days). PSS was measured by color tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE) in six myocardial walls from all three apical projections. During a median follow-up period of 5.4 years (interquartile range, 4.1-6.0 years), 180 events occurred: 59 deaths, 70 heart failures (HF) and 51 new myocardial infarctions (MI). In multivariable analysis adjusting for: age, sex, peak troponin, left ventricle ejection fraction, TIMI flow grade, left ventricle mass index, hypertension and diabetes, presence of PSS by TDI in the culprit region was associated with a nearly twofold increased risk of HF (HR 1.90, 95% CI 1.02-3.53, P = 0.043) and the risk of HF increased incrementally with increasing numbers of walls displaying PSS. The increased risk of HF was confirmed when assessing the post-systolic index by STE (HR 1.29 95% CI 1.09-1.53, P = 0.003, per 1% increase). A regional analysis showed that PSS by TDI in the septal wall was the strongest predictor of HF (HR 1.77, 95% CI 1.08-2.92, P = 0.024). Presence of PSS was not associated with increased risk of death or MI. In patients with STEMI treated with pPCI, the presence of PSS examined by TDI and STE provides prognostic information on development of HF. Presence of PSS in the septal wall is the strongest predictor of HF.

Relationship between post-systolic motion during dobutamine stress echocardiography and functional recovery of myocardium after successful percutaneous coronary intervention

BACKGROUND AND OBJECTIVES

Doppler myocardial imaging (DMI) has been suggested as a method of quantifying inducible ischemia during dobutamine stress echocardiography (DSE). Post-systolic motion (PSM) detected by DMI is related to peri-infarct ischemia during DSE. We hypothesized that PSM during DSE would predict recovery of dysfunctional myocardium after successful percutaneous coronary intervention (PCI).

SUBJECTS AND METHODS

Thirty patients with dysfunctional myocardium in the left anterior descending coronary artery (LAD) territory were divided into two groups according to improvement of wall motion score index (WMSI) in the LAD territory at 6 months after successful PCI of the LAD. DMI was evaluated in the LAD territory during DSE. Fifteen patients showed improved WMSI (1.42+/-0.39) while the other 15 had unchanged WMSI (1.75+/-0.46) 1 month after PCI. Myocardial velocity was measured in the mid-septal, apico-septal, and basal anterior segments of the LAD artery territory. PSM was defined as a positive wave appearing after the curve of systolic ejection had reached the zero line.

RESULTS

Although there was no difference between resting PSMs in both groups, PSM during DSE was significantly higher in the improved WMSI group than in the WMSI group where it was unchanged.

CONCLUSION

PSM during DSE predicts recovery of dysfunctional myocardium after successful PCI.

Positive Isovolumic Relaxation Velocity Detected by a Spectral Tissue Doppler Mapping Technique as an Indicator of Coronary Artery Disease: A Prospective Study

BACKGROUND

A positive myocardial velocity during isovolumic relaxation phase (V(IR)) detected by spectral tissue Doppler imaging has been shown to indicate ischemic myocardium. We sought to examine the diagnostic value of positive V(IR) for detecting coronary artery disease (CAD) in patients with chest pain and apparently normal left ventricular contraction.

METHODS

A total of 138 patients (74 men, age 69 +/- 8 years) underwent spectral Doppler tissue imaging measurements at the annular and mid left ventricular levels in the apical 4- and 2-chamber views (8 points/patient) at rest in addition to standard echocardiography. Subsequently, patients underwent thallium-201 myocardial perfusion single photon emission computed tomography (n = 98) and/or coronary angiography (n = 60). The duration of positive V(IR) was also assessed. CAD was diagnosed by having more than 75% diameter stenosis in coronary angiography.

RESULTS

CAD was present in 41 patients (30%). The duration of positive V(IR) was distributed from 0 to 280 milliseconds with the median value of 100 milliseconds. Presence of positive V(IR) predicted CAD with sensitivity of 80% and specificity of 61%.

CONCLUSIONS

Positive V(IR) detected by spectral tissue Doppler imaging is a useful indicator of CAD in patients with apparently normal left ventricular contraction and chest pain.

Heart rate reduction by inhibition of If or by beta-blockade has different effects on postsystolic wall thickening

BACKGROUND AND PURPOSE

Postsystolic wall thickening (PSWT) is part of thickening that occurs after end-systole and represents wasted effort as it does not contribute to ejection. The effects of antianginal drugs on PSWT remain to be established. We compared the effects on PSWT of two agents that reduce heart rate, the beta-blocker atenolol and the selective inhibitor of If current, ivabradine.

EXPERIMENTAL APPROACH

Six dogs were prepared to measure wall thickening by sonomicrometry in the conscious state, at rest and during exercise, after administration of saline, atenolol (1 mg.kg-1) or ivabradine (1 mg.kg-1).

KEY RESULTS

Atenolol and ivabradine similarly reduced heart rate vs saline at rest (about 10-20%) and during exercise (about 30%). Atenolol but not ivabradine decreased dP/dtmax. Concomitantly, PSWT increased with atenolol vs saline at rest (0.35+/-0.07 vs 0.21+/-0.03 mm, respectively) and during exercise (0.30+/-0.04 vs 0.15+/-0.04 mm, respectively). In contrast, ivabradine did not alter PSWT. Importantly, atenolol but not ivabradine increased the ratio of postsystolic to systolic wall thickening by 80+/-23%. This enhanced thickening during diastole with atenolol was accompanied by impeded isovolumic relaxation of the left ventricle, as illustrated by the significant correlation between the isovolumic relaxation time constant tau and the postsystolic to systolic wall thickening ratio. None of these effects of atenolol were abolished when heart rate was controlled with atrial pacing.

CONCLUSION AND IMPLICATIONS

For a similar heart rate reduction at rest and during exercise, ivabradine, but not atenolol, did not alter PSWT and preserved the part of thickening contributing to ejection.

Asynchrony of Left Ventricular Systolic Performance After the First Acute Myocardial Infarction in Patients with Narrow QRS Complexes: Doppler Tissue Imaging Study

BACKGROUND

Left ventricular (LV) electromechanical delay results in asynchronized contraction. However, it is not known if the presence of cardiac diseases without QRS prolongation may result in interventricular or intraventricular asynchrony. Doppler tissue imaging is now established for detecting regional contractile abnormalities and asynchrony in the LV.

OBJECTIVES

The aim of the study was to assess the degree of LV asynchrony after the first acute myocardial infarction (AMI) in patients with a narrow QRS complex using Doppler tissue imaging and correlate this with the site and extent of the infarction.

METHODS

Echocardiography with Doppler tissue imaging was performed within 1 week of AMI in 155 patients and compared with 50 age- and sex-matched healthy volunteers. Regional myocardial velocities were assessed at the 4 mitral annular sites, and the corresponding systolic velocity (Sm), early diastolic velocity (Em), time to peak Sm (Ts), and time to peak Em (Te) were measured. To assess LV synchronicity, SDs of Ts (Ts-SD) and Te (Te-SD) of all the 4 mitral annular sites were computed. Location and size of infarct were confirmed by echocardiographic wall-motion score index.

RESULTS

QRS complex duration was normal in all patients. Wall-motion score index was significantly higher in patients with anterior than inferior AMI (2.02 +/- 0.34 vs 1.24 +/- 0.21, P < .001). Ts-SD was significantly higher in patient than control group, and in patients with anterior than inferior AMI (38.21 +/- 2.59 vs 21.06 +/- 0.52 milliseconds and 43.18 +/- 3.77 vs 33.24 +/- 1.4 milliseconds, respectively, P < .001 for each), whereas Te-SD did not differ significantly among these groups (20.35 +/- 1.77 vs 18.17 +/- 1.14 milliseconds and 21.6 +/- 1.35 vs 19.1 +/- 1.11 milliseconds, respectively, P > .05 for each). A strong positive correlation was detected between LV systolic asynchrony (Ts-SD) and wall-motion score index (r = .77), LV mass (r = .67), LV end-systolic dimension (r = .65), and LV end-diastolic dimension (r = .5). The correlation was negative with LV ejection fraction (r = -.70) and Sm (r = -.6); the correlation was weak with Em (r = -.33) (P < .001 for all). In multivariate logistic regression analysis, infarct size was found to be the most independent predictor for systolic asynchrony (odds ratio 3.59, 95% confidence interval [1.43-9.33], P < .001).

CONCLUSION

AMI has a significant impact on regional myocardial contractility and LV systolic (but not diastolic) synchronicity early in the course even in the absence of QRS widening or bundle branch block. The degree of LV systolic asynchrony is greater with anterior than inferior AMI and mainly determined by infarct size.

Tissue Doppler imaging for the diagnosis of coronary artery disease

PURPOSE OF REVIEW

Tissue Doppler imaging (TDI) is a diagnostic method that provides quantitative data about myocardial function. The present review discusses the most recent developments in the application of TDI in coronary artery disease.

RECENT FINDINGS

The most widely used TDI modality is velocity imaging, and systolic function is measured as peak velocity during LV ejection. Several recent studies show that TDI measurements during the LV isovolumic phases provide unique information regarding myocardial dysfunction. Since velocity imaging is confounded by influence from velocities in other segments, the TDI-based modalities strain- and strain rate imaging (SRI) have been introduced to measure regional shortening fraction and shortening rate, respectively.Velocity imaging during stress echocardiography has been validated clinically and appears equivalent, but not superior to conventional visual assessment of grey scale images. Potentially, more comprehensive evaluation that includes the use of SRI may improve the diagnostic power of TDI further. Preliminary reports suggest that TDI may have an important role in the assessment of viability in acute coronary occlusion, but this needs to be demonstrated in appropriately designed clinical trials.

SUMMARY

At the present time tissue Doppler velocity imaging can be recommended for clinical use, especially the pulsed mode. Strain rate imaging may be useful as additional imaging, but needs further refinement before it is ready for routine clinical use.