Menoufia Medical Journal

ORIGINAL ARTICLE
Year
: 2015  |  Volume : 28  |  Issue : 2  |  Page : 400--405

Assessment of left ventricular function before and after a percutanous coronary intervention to chronic total coronary occlusion: Doppler tissue imaging study


Wessam H El Shafey1, Said S Montaser1, Hala M Badran1, Mahmoud K Gabr1, Khaled A Shokry2, Alfredo R Galassi3,  
1 Department of Cardiology, Faculty of Medicine, Menoufia University, Shebein El Kom, Egypt
2 Department of Cardiology, Kobry El Kobba Military Hospital, Cairo, Egypt
3 Department of Cardiology, Cannizarro Hospital, Catania University, Catania, Italy

Correspondence Address:
Wessam H El Shafey
Cardiology Department, Faculty of Medicine, Menoufia University, St. Yassin Abd El Ghaffar, Shebein El Kom - 32111, El Menoufia
Egypt

Abstract

Background The rationale for the recanalization of chronic total occlusion (CTO) is the possible improvement in left ventricular (LV) function through the recovery of hibernating myocardium. Tissue Doppler imaging (TDI) can be used for the assessment of global and regional LV function with high temporal and spatial resolution. Purpose This study aimed to assess LV function before and after CTO-percutanous coronary intervention (PCI) by pulsed wave (PW)-TDI. Patients and methods The present study enrolled 40 patients with CTO; 37 completed the final follow-up: 22 patients did not have infarction in the territories of recanalized CTO vessel (group I), and 15 patients had infarction in the CTO territories of recanalized CTO vessel (group II). All patients were subjected to conventional M-mode and two-dimensional echo-Doppler and TDI examination. PW-TDI was used to assess the velocity curves of basal and mid segments of the septal, lateral, anterior, inferior, posterior, and anteroseptal LV walls. The following indices were measured: Tp, Sv, E0΄, A΄, E΄/ A΄, acceleration of isovolumic contraction (IVC), isovolumic relaxation period, isovolumic contraction time (IVCT), contraction time, and TEI index. Results After recanalization of the CTO vessel by PCI, the patients in the noninfarction group showed a highly significant improvement in left ventricular ejection fraction% after 3 months of follow-up (P < 0.001), whereas the infarction group did not show any significant improvement (P = NS). In the LAD, left circumflex, and right coronary artery subgroup, noninfarction patients showed a reduction in left ventricular end-systolic volume, and increased fraction shorting% and ejection fraction% after 3 months of follow-up; also, there were improvements in TDI parameters in the form of increased E΄ and acceleration of IVC in all three subgroups and increased E΄/ A΄ in LAD and left circumflex, and an increase in the peak velocity of IVC and a reduction in A΄ and time to peak of IVC in both LAD and right coronary artery; only the S wave velocity increased in the LAD subgroup after 3 months of follow-up. Conclusion In patients with CTO, acceleration of IVC measured by PW-TDI can differentiate early improvement after successful recanalization of the CTO vessel by PCI. Noninfarction territories might show earlier recovery than that in patients with evident myocardial infarction.



How to cite this article:
El Shafey WH, Montaser SS, Badran HM, Gabr MK, Shokry KA, Galassi AR. Assessment of left ventricular function before and after a percutanous coronary intervention to chronic total coronary occlusion: Doppler tissue imaging study.Menoufia Med J 2015;28:400-405


How to cite this URL:
El Shafey WH, Montaser SS, Badran HM, Gabr MK, Shokry KA, Galassi AR. Assessment of left ventricular function before and after a percutanous coronary intervention to chronic total coronary occlusion: Doppler tissue imaging study. Menoufia Med J [serial online] 2015 [cited 2020 May 25 ];28:400-405
Available from: http://www.mmj.eg.net/text.asp?2015/28/2/400/163892


Full Text

 Introduction



Chronic total occlusion (CTO) is a common condition in patients with coronary artery disease, and represents one of the most challenging targets of lesion recanalization for percutanous coronary interventions (PCIs) [1],[2] .

The rationale for the recanalization of a chronic total coronary occlusion is the possible improvement of left ventricular (LV) function through the recovery of hibernating myocardium [3],[4] .

Two-dimensional (2D) echocardiography has been described as the ideal imaging modality for the assessment of global and regional ventricular function. However, conventional assessment of wall motion, on the basis of visual interpretation of endocardial excursion and myocardial thickening, has the limitations of being a qualitative method, and is subjective and experience dependent [5] .

Tissue Doppler imaging (TDI) is an extension of conventional Doppler echocardiography; a modification in the image acquisition process now enables direct measurements of tissue velocities. The initial application of TDI in quantifying myocardial mechanical activity was to measure the peak systolic and diastolic tissue velocities of the given segment and the results have been promising so far [6] .

The present study examines the effects of successful recanalization of CTO on LV function in different groups of patients by TDI.

 Patients and methods



Our study included 40 patients prospectively recruited from the period of August 2010 till August 2013; only 37 of these patients successfully completed the entire study protocol. The study was carried out in Kobry El Koba Military Hospital, Egypt, and Cannizzaro Hospital, Catania University, Italy.

Inclusion criteria

Patients with known chronic total coronary artery disease proved by previous diagnostic coronary angiography and eligible for PCI and in sinus rhythm on surface ECG were enrolled.

Exclusion criteria

Individuals with poor echocardiographic recordings, significant valvular heart disease, supraventricular or ventricular arrhythmias, and pericardial diseases were excluded.

The study protocol was approved by the Institutional Clinical Research and Ethics Committee of Menoufia University Hospital, and all of the patients provided written informed consent.

All individuals were subjected to a full assessment of history, a thorough clinical examination, laboratory investigation, and resting 12-lead ECG.

Echocardiographic study

The echocardiographic study was carried out within 24 h before and 3 months after performing the PCI according to the recommendation of the American Society of Echocardiography [7] . General Electric Vivid 7 (GE Ultrasound, Horten, Norway) machines equipped with the TDI mode with 2-2.5 MHz transthoracic transducers were used.

Conventional 2D, M-mode, and Doppler studies were carried out; transmitral peak early diastolic inflow velocity (E), peak late diastolic inflow velocity (A), and the E/A ratio were determined. Pulsed wave (PW)-TDI was performed; the high pass filter was bypassed and lower gain amplification was used. An LV 16-segment model was used according to the recommendation of the American Society of Echocardiography. TDI data were obtained from the apical 4, 3, and 2 chambers; each wall was divided into three segments of equal length to obtain basal, mid, and apical segments. The apical segments were not analyzed because of suboptimal image quality. The segments were classified according to the feeding coronary artery as follows:

(1) Left anterior descending (LAD): mid septal, basal, mid anterior, and anteroseptal walls.

(2) Left circumflex (LCX): mid, basal lateral, and mid, basal posterior walls.

(3) Right coronary artery (RCA): basal septal, mid, and basal inferior walls.

The Doppler velocity range was adjusted from −30 to +30 cm/s, with a sweep speed of 100 mm/s. A mean of three consecutive cycles was used for the calculations of all echocardiographic Doppler parameters.

Pulsed wave-tissue Doppler imaging parameters

Biphasic signals during the isovolumic contraction (IVC) period and isovolumic acceleration (IVA) were determined [Figure 1]. Systolic wave (S): peak velocity and duration. Biphasic signal during the isovolumic relaxation period was assessed. An early diastolic velocity wave (E'), a late diastolic velocity wave (A'), and the E'/A' ratio were calculated.{Figure 1}

Coronary angioplasty

CTO was defined as lumen compromise resulting in either TIMI flow grade 0 or 1, with a likely duration of more than 3 months [1] . All the patients included had a native vessel occlusion estimated to be of at least 3 months in duration on the basis of a history of sudden chest pain, a previous myocardial infarction (MI) in the same target vessel territory, or the time between the diagnosis made on coronary angiography and PCI. All the patients had symptomatic angina and/or a positive functional ischemia study. PCI and stent implantation were performed in a standard manner. Drug-eluting stents were used in all of the angioplasty procedures. PCI of the CTO was performed using modern techniques such as bilateral injections; specialized hydrophilic, tapered tip, and stiff wires; parallel wires; microcatheters; and a retrograde approach when possible. Procedural success was defined as the successful recanalization of CTO with a residual stenosis of less than 20% and a TIMI flow of more than 2.

The diameter and angiographic flow of collateral vessels were assessed semiquantitatively using the collateral connection grade (CC0 = no continuous connection, CC1 = continuous thread- like connection, and CC2 = continuous, small branch-like connection) [9] .

Statistical analysis

The data were analyzed using the statistical package for the social sciences (version 14.0; SPSS Inc., Chicago, Illinois, USA) software for Windows. Continuous variables were expressed as mean ± SD and categorical variables were expressed as a percentage. A P value less than 0.05 was considered statistically significant. A χ2 -test was used for the comparison of qualitative data. Pearson's correlation was used to measure the association between two quantitative variables. Multivariable regression analysis was used to predict values of one variable on the basis of two or more other variables.

 Results



Our study included 40 patients with coronary artery disease, in whom one vessel was chronically totally occluded. Thirty-seven of the patients recruited completed the full study protocol.

The patients were divided into two groups: group I included 22 patients (LAD: 10, RCA: 6, LCX: 6) without previous MI in the territories of total occlusion vessel that was recanalized and group II included 15 patients (LAD: 7, RCA: 6, LCX: 2) with previous MI in the territories of total occlusion vessel that was recanalized. There was no significant difference between the two groups in anthropometric measurements. In terms of symptomatology, the patients in group I were more symptomatic than those in group II, especially anginal pain (P < 0.01). The patients in group I also had higher baseline ejection fraction% (EF%) than those in group II (P < 0.05) [Table 1], [Figure 2].{Figure 2}{Table 1}

Risk factors for coronary artery disease including hypertension, diabetes mellitus, dyslipidemia, and smoking were more prevalent in group II than group I, especially smoking (P = 0.01) and diabetes mellitus (P = 0.02).

After 3 months of follow-up, there were no recurrent anginal symptoms since the day after PCI to CTO vessel. Our patients were subdivided into three subgroups according to the target CTO vessel where we compared each subgroup for the conventional and TDI echocardiographic parameters before PCI on the CTO vessel and 3 months after PCI.

In the LAD, LCX, and RCA subgroup, noninfarction patients showed a reduction in left ventricular end-systolic volume (LVESv), and increased fraction shorting% (FS%) and EF% after 3 months of follow-up; also, there were improvements in TDI parameters in the form of increased E' and IVA in all three subgroups and increased E'/A' in LAD and LCX and increased peak velocity of IVC, and reduction of A' and time to peak of IVC in both LAD and RCA. Only the S wave velocity increased in the LAD subgroup after 3 months of follow-up [Table 2], [Figure 3].{Figure 3}{Table 2}

A positive correlation was found between the mean IVA and each Werner classification of coronary collaterals, FS%, and EF%, and a negative correlation was found with BMI, LVEDv, and LVESv. Multivariable regression analysis showed that the independent predictor of the mean IVA was the Werner classification (P = 0.012).

 Discussion



To our knowledge, this is the first study to assess LV global and regional myocardial functions in CTO patients by PW-TDI, where we have shown that improvement in regional and global LV function measured by PW-TDI in patients with CTO vessel after successful recanalization by PCI could occur especially in noninfarction myocardial territories. A growing body of studies has shown that the mechanisms by which PCI of an occluded infarct-related artery might improve outcomes include reduction in adverse LV remodeling with preservation of LV function, increased electrical stability, and provision of collateral vessels for protection against future events [10],[11] .

The rationale for the recanalization of a chronic total coronary occlusion is the possible improvement in LV function through the recovery of hibernating myocardium [3],[4] .

The concept of hibernating myocardium was introduced a decade ago by Braunwald and Rutherford [12] and Rahimtoola [13] . The term describes persistent myocardial dysfunction at rest because of underperfusion, with subsequent improvement upon revascularization [12],[13] .

TDI is an extension of conventional Doppler echocardiography. The initial application of TDI in quantifying myocardial mechanical activity was to measure the peak systolic and diastolic tissue velocities of the given segment and the results have been promising so far [5] . The diagnostic power of TDI may be improved by measuring isovolumic velocities besides ejection velocities, especially in severely ischemic and dyskinetic myocardium [14] .

Pre-ejection velocity changes can be explained by the fact that myocardial velocity is determined by the rate of increase of LV pressure and by myocardial elastic properties as most of the LV systolic pressure generated during IVC and the rate of increase of LV pressure (dp/dt) reaches the maximum during IVC and is less during ejection; thus, the IVC velocity is larger than the peak ejection velocity and may be a more sensitive marker of severely ischemic myocardium, and a positive IVC velocity might predict the recovery of contractile function after revascularization [8] .

Vogel et al. [8] hypothesized that IVC would be less load dependent than ejection phase indices. In a pig model, they also calculated myocardial IVA from TDI velocities and showed a correlation between IVA and measures of global LV contractility. Furthermore, they found that IVA was unaffected by relatively large preload reductions and after load increases.

The improvement in systolic and diastolic LV function that occurred after 3 months, represented by FS%, EF%, S wave velocity, isovolumic contraction peak velocity (IVCPv), and IVA and E', A', and E'/A' ratio, respectively, in the patients in group I may thus be an indication of recovered hibernating myocardium. It is probable that angina pectoris related to the occluded vessel in such groups of patients may have been a marker for regions with hibernation.

Several studies have reported improvements in LV function after successful recanalization of chronic coronary occlusions [3,15,16]. Some studies showed that LV volume changes after MI depended on the patency status of the infarct-related artery. When the infarct-related artery was totally occluded, a significant increase in both end-diastolic and end-systolic volumes occurred, with a resulting decrease in EF [17] .

It can be observed from our results that there is unequal recovery among LAD, RCA, and LCX CTO patients, where the LAD patients showed more constant improvement in both systolic and diastolic regional TDI parameters; this may be because the LAD territories are represented by more myocardial segments than the other arteries, despite this unequal improvement in TDI parameters but it seems that IVA is commonly improved among all patients of group I irrespective of the target CTO vessel.

This is in agreement with the findings of Ozkan et al. [18] , who evaluated the RV functions by TDI and 2D speckle tracking echocardiography, and they reported that there was an improvement in the IVA by TDI and 2D-STE-derived global longitudinal strain and systolic strain rate values in RV functions after successful recanalization of CTO RCA.

Our findings of a less robust coincident change in the S wave velocity and IVCPv and IVA in both groups of RCA and LCX without infarction can be explained by the hypothesis that segments with residual viability, not enough to achieve significant functional systolic recovery, may generate segmental shortening during IVC, but not to overcome the after load during the ejective phase. Thus, these segments would remain dysfunctional during ejection despite residual viability [19] . These data are in agreement with those of Penicka et al. [14] , who underlined that the IVCPv could overestimate the prediction of myocardial recovery.

 Conclusion



Acceleration of IVC measured by PW-TDI can differentiate early improvement after successful recanalization of CTO vessel by PCI, non-infarction territories might recover at earlier stage than patients with evident infarction territories.

Limitations

The limited number of patients, short-term follow-up, and the fact that this was a single-center study could limit the strength of the results. The Doppler technique relies on parallel alignment of the Doppler beam to the moving objects; thus, angulations can affect the results. However, it could be minimized by choosing the region of interest within 15-20° of the axis of the Doppler interrogation.

TDI measurements are affected by cardiac translational movements and the tethering effect from adjacent ischemic segments; it can be minimized using strain rate and tissue tracking techniques.

 Acknowledgements



The authors thank all the participants in the study.

Conflicts of interest

There are no conflicts of interest.

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