Analysis of systolic and diastolic time intervals during dobutamine-atropine stress echocardiography: diagnostic potential of the Doppler myocardial performance index

Myocardial performance index is associated with cardiac computed tomography findings in patients with suspected coronary artery disease

BACKGROUND

Studies suggest cardiac time intervals to be associated with cardiac ischemia. A novel method to assess cardiac time intervals by tissue Doppler echocardiography has been proposed. Cardiac time intervals can assess the myocardial performance index (MPI), which quantifies the proportion of time spent contributing effective myocardial work. We hypothesized that MPI associates with coronary artery lesions detected by cardiac computed tomography (CT) in patients suspected of coronary artery disease (CAD).

METHODS

We investigated patients referred for cardiac CT under suspicion of CAD who had an echocardiogram performed. Curved m-mode tissue Doppler imaging was used to measure cardiac time intervals and MPI. The outcome was coronary artery lesions, defined as a calcium score > 400 and/or coronary artery stenosis (>70% luminal narrowing). Logistic regression was applied with multivariable models including: (a) SCORE chart risk factors and (b) SCORE chart risk factors, body mass index, dyslipidemia, familial history of CAD, diabetes mellitus, LVEF, and left ventricular mass index.

RESULTS

Of 404 patients, 41 (10%) had a coronary artery lesion. Overall, 42% were male, mean age was 58 years, and LVEF was 58%. Patients with coronary artery lesions exhibited higher MPI than those without (0.52 vs. 0.44, P < .001). MPI associated with coronary artery lesions in unadjusted analyses (OR = 1.69 [1.30-2.19], per 0.1 increase), and this association persisted when adjusted for SCORE chart risk factors (OR = 1.55 [1.16-2.07], P = .003, per 0.1 increase), and additional risk factors (OR = 1.64 [1.11-2.41], P = .013, per 0.1 increase).

CONCLUSION

Curved m-mode-derived MPI is associated with coronary artery lesions detected by cardiac CT in suspected CAD patients.

The Assessment and Potential Implications of the Myocardial Performance Index Post Exercise in an at Risk Population

BACKGROUND

The myocardial performance index (MPI) first described by Chuwa Tei in 1995 is a relatively new echocardiographic variable used for assessment of overall cardiac function. Previous studies have demonstrated the MPI to be a sum representation of both left ventricular systolic and diastolic function with prognostic value in patients with coronary artery disease as well as symptomatic heart failure.

METHODS

Ninety patients with either established coronary artery disease (CAD) or CAD risk factors underwent routine treadmill exercise stress testing with two-dimensional Doppler echocardiography using the standard Bruce protocol. Both resting and stress MPI values were measured for all 90 of the patients.

RESULTS

Using a normal MPI cut off of ≤ 0.47, the prevalence of an abnormal resting MPI in our 90 subjects was 72/90 or 80% and the prevalence of an abnormal stress MPI in our 90 subjects was 48/90 or 53.33%. The average MPI observed in the resting portion of the stress test for the cohort was: 0.636 with a standard deviation of 0.182. The average MPI in the stress portion of the stress test for the cohort was 0.530 with a standard deviation of 0.250. The P value with the use of a one-tailed dependent T test was calculated to be < 0.05.

CONCLUSION

We postulate that these findings reflect that the MPI (Tei) index assessed during exercise may be a sensitive indicator of occult coronary disease in an at risk group independent of wall motion assessment.

The Tei index and asymptomatic myocarditis in children with severe dengue

This study aimed to assess myocardial involvement in infants and children with severe dengue (as per the new World Health Organization [WHO] classification 2009) using the Tei index. This prospective observational study was conducted in the Department of Pediatrics, PGIMER and the associated Dr. RML Hospital, New Delhi from August to December 2010. The study included 67 children (ages 3 months-14 years) who satisfied the WHO criteria for the diagnosis of probable dengue fever with warning signs or severe dengue and tested positive for dengue via immunoglobulin-M (IgM) capture enzyme-linked immunoassay (MAC-ELISA). The patients were subjected to a complete blood count, liver function tests, renal profile, electrocardiography, myocardial band enzymes of creatine phosphokinase (CPK-MB), chest x-ray, abdomen ultrasonography, and two-dimensional echocardiography with color-flow Doppler mapping. Ejection fraction and Tei index measurements were performed. Significantly fewer patients with severe dengue were found to have myocardial involvement at admission by ejection fraction (48 %) and E/E' (37 %), than by the Tei index (70 %). Of the 67 patients with severe dengue, one died, giving a case fatality rate of 1.5 %. At discharge, the Tei index persisted on the high side for patients with myocardial involvement, whereas the ejection fraction improved for the majority of them. Most of the patients with severe dengue had asymptomatic myocarditis, as evident by a deranged Tei index, which improved but did not normalize by the time of discharge, necessitating a longer follow-up period. For the majority of the patients, inotropic support was not required to maintain hemodynamic stability.

Relationship between myocardial performance index and severity of coronary artery disease assessed with SYNTAX score in stable coronary artery disease

BACKGROUND

The aim of the study was to investigate the relationship between severity of coronary artery disease (CAD) assessed with SYNTAX score (SS) and myocardial performance index (MPI) in stable CAD.

METHODS

The study participants consisted of 106 consecutive patients (mean age: 57.6 ± 9.5 years) with angiographically proven obstructive stable CAD and 30 patients with nonobstructive CAD (control group) (mean age: 58.0 ± 7.6 years). The MPI was calculated by using pulsed-wave Doppler before coronary angiography. Coronary angiography was performed in all patients. The SS was prospectively calculated in 106 obstructive CAD patients. Patients were partitioned into 3 groups based on SS. Frequencies of risk factors, biochemical and hematological data were recorded in all patients.

RESULTS

The SS tertiles were defined as SS(low) ≤ 8 (n = 35), SS(mid) ≤ 17 (n = 36), and SS(high) > 17 (n = 35). The patients with SS(high) group (mean MPI; 0,48 ± 0.06) based on SS had significantly higher MPI values compared with the SS(mid) (mean MPI; 0,44 ± 0.05), SS(low) (mean MPI; 0.43 ± 0.06), and control (mean MPI; 0.41 ± 0.05) groups (P < 0.05 for all). The MPI levels of control group were also lower than compared with SS(mid) group (P = 0.006). The MPI value was significantly correlated with SS (r = 0.564, P < 0.001), diabetes (r = 0.355, P < 0.001), hypertension (r = 0.326, P < 0.001), and ejection fraction (EF) (r = -0.224, P = 0.018) in bivariate analysis. Multivariate regression analysis showed that MPI was independently associated with SS (β = 0.486, P < 0.001) and diabetes (β = 0.205, P = 0.028).

CONCLUSION

Although the normal EF, MPI value was impaired in proportion to the severity of CAD in patients with stable CAD.

Infarto agudo do miocárdio e injeção intramiocárdica experimental em cães: estudos clínico, enzimático, eletrocardiográfico e ecocardiográfico

Os eventos isquêmicos em cães são incomuns, porém podem estar sendo subnotificados. Avaliou-se o infarto agudo do miocárdio (IAM) clinicamente, por meio de eletrocardiografia (ECG), eletrocardiografia contínua (EC), ecocardiografia (ECO), enzima creatina quinase (CK), enzima creatina quinase fração MB (CK-MB) e anátomo-histologicamente em cães sem raça definida, e observou-se a ocorrência de arritmias após injeção intramiocárdia por EC. O IAM foi obtido após a ligadura da coronária descendente anterior. Os animais apresentaram ao ECO dilatação da câmara esquerda e aumento do índice de desempenho miocárdico. Ao ECG houve desnivelamento de ST nas derivações pré-cordiais V1 e V2. No EC observaram-se arritmias ventriculares graves e supradesnivelamento de ST. As enzimas CK e CK-MB aumentaram significativamente, sendo que os picos de CK-MB e de CK ocorreram seis horas e 12 horas, respectivamente, após o IAM. Na análise histológica constatou-se infarto da parede inferior do ventrículo esquerdo e substituição do tecido muscular por tecido fibroso. Avaliou-se a injeção intramiocárdica por EC que pode servir como via terapêutica cardíaca, não sendo observado aumento das arritmias ventriculares após a injeção no miocárdio infartado. O infarto em cães pode ser detectado pelos exames cardíacos disponíveis, e a injeção intramiocárdica é uma via terapêutica cardíaca possível.

The clinical value of the Tei index among Nigerians with hypertensive heart failure: correlation with other conventional indices

BACKGROUND

Various conventional methods are used for functional evaluation and risk stratification in heart failure. A combined index of global myocardial performance called the Tei index has been described. The aim of this study was to evaluate the correlation of the Tei index with other conventional indices of systolic and diastolic function among Nigerians with hypertensive heart failure.

METHODS

Fifty-five subjects with hypertensive heart failure and 30 controls were examined, a clinical history was taken, and echocardiography was performed on them. The subjects were categorised into four groups based on their ejection fraction (normal ejection fraction, mild, moderate and severe heart failure). The Tei index was calculated as the sum of the isovolumic relaxation and contraction time, divided by the ejection time. Statistical analysis was done using SPSS 16.0.

RESULTS

The Tei index was significantly higher among subjects with hypertensive heart failure compared with the controls (0.91 ± 0.33 vs 0.28 ± 0.16, p < 0.005). The Tei index also increased with the severity of the heart failure and was inversely correlated with ejection fraction (r = -0.697, p < 0.001) and fractional shortening (r = -0.580, p = 0.001). It was directly correlated with mitral E/A ratio (r = 0.246, p = 0.030), left ventricular internal diastolic dimension (r = 0.414, p = 0.002), left ventricular internal systolic dimension (r = 0.596, p < 0.001) and deceleration time (r = 0.219, p = 0.032).

CONCLUSION

The Tei index correlated significantly with other conventional indices of systolic and diastolic function among Nigerians with hypertensive heart failure. It can be used as a risk-stratification index similar to other traditional indices of systolic and diastolic function.

Índices ecoDopplercardiográficos de função ventricular esquerda em cães das raças Boxer e Schnauzer Miniatura

Avaliaram-se o índice de performance do miocárdio (IPM) e outros índices ecoDopplercardiográficos de função ventricular em cães de duas raças de diferentes biotipos. Foram utilizados 24 cães da raça Schnauzer Miniatura, com média de peso de 8,4±1,6kg, e 24 cães da raça Boxer, com média de peso de 25,1±2,6kg. O IPM na raça Schnauzer Miniatura foi 0,32 e na raça Boxer 0,48. Os valores do IPM, dos índices de fase de ejeção, do período de pré-ejeção, da relação período de pré-ejeção/período de ejeção e do tempo de desaceleração da onda E do fluxo mitral diferiram entre as duas raças. Observou-se correlação entre o peso corporal e esses índices, e o peso corporal foi considerado a principal característica racial responsável pelas diferenças observadas. O tempo de ejeção (r=-0,51), o período de pré-ejeção (r=-0,44) e o tempo de relaxamento isovolumétrico (r=-0,38) foram os únicos parâmetros a apresentar correlação com a freqüência cardíaca (FC). O uso da relação período de pré-ejeção/tempo de ejeção e do tempo de ejeção corrigido pela freqüência cardíaca diminui o efeito da FC sobre esses parâmetros.

Proinflammatory cytokines and cardiac abnormalities in uncomplicated obesity: relationship with abdominal fat deposition

BACKGROUND AND AIM

Obesity can be considered a state of chronic, low-grade inflammation. Particularly, visceral adipose tissue (VAT) seems to be an active compartment in pro-inflammatory molecule secretion. The possible existence of a correlation between circulating cytokines, their soluble receptors, abdominal fat accumulation and echocardiographic abnormalities in uncomplicated obesity was investigated.

METHODS AND RESULTS

Echocardiographic parameters, C-reactive protein (CRP), interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6-R), tumor necrosis factor-alpha (TNF-alpha) and soluble TNF receptor I (TNFR-I) were assessed in 27 normotensive obese women (age 33.3+/-8.3 years; BMI 43.5+/-4.8 kg/m2) and 15 normal-weight controls (age 36.8+/-8.2 years; BMI 22.6+/-1.7 kg/m2). VAT was assessed by CT. The obese patients had higher serum IL-6 (p<0.01), sIL-6-R (p<0.0001), sIL-6-R/IL-6 complex (p<0.05), TNF-alpha (p<0.02), sTNF-alpha-RI (p<0.03) and CRP (p<0.0001) levels than normal women. Moreover, end-diastolic septum thickness (SW), end-diastolic posterior wall thickness (PW), absolute and indexed left ventricular mass, deceleration time (DT), myocardial performance index (MPI) and isovolumetric relaxation time (IVRT) were correlated with sIL-6-R, sIL-6-R/IL-6 complex and CRP levels. Interestingly, sIL-6-R, sIL-6-R/IL-6 complex, CRP, SW, PW, DT and MPI were higher in patients with a VAT area >130 cm2 than those with <130 cm2.

CONCLUSION

In normotensive obese women several pro-inflammatory molecules correlate with both echocardiographic abnormalities and the amount of intra-abdominal fat; these results may support a role for visceral fat in predisposing to cardiac dysfunction, possibly through a low-grade state of inflammation.

Changes in the Doppler myocardial performance index during dobutamine echocardiography: association with neurohormonal activation and prognosis after acute myocardial infarction

OBJECTIVES

To test whether an increase in Doppler myocardial performance index (MPI) during dobutamine stress echocardiography, reflecting deterioration of overall left ventricular function, is associated with increased N-terminal pro-brain natriuretic peptide (NT-pro-BNP) concentration and provides prognostic information beyond conventional systolic wall motion analysis after acute myocardial infarction (AMI).

DESIGN

Prospective, observational study.

METHODS

Dobutamine-atropine stress echocardiography (DASE) and NT-pro-BNP were assessed five days after AMI in 109 consecutive patients. MPI was measured at rest and at low-dose (10 microg/kg/min) and peak dobutamine infusion (<or= 40 microg/kg/min with or without atropine).

MAIN OUTCOME MEASURES

End point was a composite of cardiac death or readmission for heart failure or reinfarction.

RESULTS

In 35 patients (32%), MPI increased at low-dose DASE. This was associated with higher NT-pro-BNP concentrations (beta = 0.30, p = 0.004). During a mean follow up of 27 (SD 7) months, 8 patients died of cardiac causes and 15 patients were readmitted for heart failure or reinfarction. On Cox regression analysis, an increase in MPI at low-dose DASE (p = 0.02) was an independent predictor of cardiac events. In contrast, traditional wall motion analysis during DASE provided no additional prognostic information.

CONCLUSIONS

An increase in MPI at low-dose DASE, reflecting early deterioration of overall left ventricular function, is associated with raised NT-pro-BNP concentration and provides prognostic information beyond conventional stress echocardiographic data after AMI.

Comparison of xenon-based anaesthesia compared with total intravenous anaesthesia in high risk surgical patients

Xenon, a noble gas with anaesthetic and analgesic properties, has gained renewed interest due to its favourable physical properties which allow a rapid emergence from anaesthesia. However, high costs limit its use to a subset of patients who may benefit from xenon, thereby offsetting its costs. To date, there are only limited data available on the performance of xenon in high risk patients. We studied 39 patients with ASA physical status III undergoing aortic surgery. The patients were randomly assigned to either a xenon (Xe, n = 20) or a TIVA (T, n = 19) group. Global cardiac performance and myocardial contractility were assessed using transoesophageal echocardiography, and myocardial cell damage with troponin T and CK-MB. Echocardiographic measurements were made prior to xenon administration, following xenon administration, and after clamping of the abdominal aorta, after declamping and at corresponding time points in the TIVA group. Laboratory values were determined repeatedly for up to 72 h. Data were analysed using two-way anova factoring for time and anaesthetic agent or with ancova comparing linear regression lines. No significant differences were found in global myocardial performance, myocardial contractility or laboratory values at any time during the study period. Mean (SEM) duration of stay on the ICU (xenon: 38 +/- 46 vs. TIVA 25 +/- 15 h) or in hospital (xenon: 14 +/- 12 vs. TIVA 10 +/- 6 days) did not differ significantly between the groups. Although xenon has previously been shown to exert superior haemodynamic stability, we were unable to demonstrate an advantage of xenon-based anaesthesia compared to TIVA in high risk surgical patients.

Close Coupling of Systolic and Diastolic Function: Combined Assessment Provides Superior Prediction of Exercise Capacity

BACKGROUND

Isolated diastolic dysfunction is thought to account for approximately 50% of cases of heart failure. We tested the hypotheses that (1) the use of different methods for assessing systolic and diastolic function may contribute to the apparent frequency with which they are dissociated and (2) that combined assessment of systolic and diastolic function is superior to either one alone.

METHODS AND RESULTS

A total of 110 patients underwent echocardiography with tissue Doppler imaging (TDI) of the mitral annulus before maximal exercise testing. The correlation between left ventricular (LV) ejection fraction (EF) and exercise capacity was weak (r = 0.199). Among patients with EF greater than 55%, those with normal exercise capacity (>7 METs) had a higher systolic velocity of the mitral annulus than those achieving less than 7 METs (9.6 +/- 0.3 versus 7.5 +/- 0.4 cm/s, P = .001). The mitral annular systolic (Sa) and early diastolic (Ea) velocities each correlated moderately with exercise tolerance (r = 0.40 and 0.49, respectively). Sa and Ea correlated highly with each other (r = 0.79, P < .001). The sum of isovolumic contraction and relaxation times measured from TDI correlated moderately with exercise duration (r = -0.59). A combined index of systolic and diastolic function that includes isovolumic contraction and relaxation times and ejection time had the best correlation with achieved METs (r = -0.73, P < .001). A TDI index of cardiac performance higher than 0.52 had excellent sensitivity (86%) and specificity (100%) for predicting reduced exercise tolerance lower than 7 METs.

CONCLUSION

When assessed with the same technique, LV systolic and diastolic function are tightly linked. A TDI-derived combined index of myocardial performance is the best predictor of exercise capacity.

Sevoflurane but Not Propofol Preserves Myocardial Function During Minimally Invasive Direct Coronary Artery Bypass Surgery

Volatile anesthetics exert cardioprotective properties in experimental and clinical studies. We designed this study to investigate the effects of sevoflurane on left ventricular (LV) performance during minimally invasive direct coronary artery bypass grafting (MIDCAB) without cardiopulmonary bypass. Fifty-two patients scheduled for MIDCAB surgery were randomly assigned to a propofol or a sevoflurane group. Apart from the anesthetics used, there was no difference in surgical and anesthetic management. After determination of cardiac troponin T, creatine kinase, and creatine kinase MB, electrocardiographic (ECG) data and echocardiography variables (myocardial performance index and early to atrial filling velocity ratio) the left anterior descending coronary artery (LAD) was clamped until anastomosis with the left internal mammary artery was completed. During LAD occlusion and during reperfusion, echocardiography measurements were repeated. Blood samples were obtained repeatedly for up to 72 h. After LAD occlusion, myocardial performance index and early to atrial filling velocity ratio in the propofol group deteriorated significantly from 0.40 +/- 0.12 and 1.29 +/- 0.35 to 0.49 +/- 0.10 and 1.13 +/- 0.22, respectively, whereas there was no change in the sevoflurane group. In the propofol group myocardial performance index remained increased (0.47 +/- 0.11) compared with baseline during reperfusion. There were no significant differences in ECG and laboratory values between groups. In conclusion, during a brief period of ischemia in patients undergoing MIDCAB surgery, sevoflurane preserved myocardial function better than propofol.

The myocardial performance index during low-dose dobutamine echocardiography in control subjects and patients with a recent myocardial infarction: a new index of left ventricular functional reserve?

BACKGROUND

Wall-motion analysis during low-dose dobutamine echocardiography (LDDE) is a semiquantitative measure of left ventricular contractile reserve after myocardial infarction (MI). The Doppler echocardiographic myocardial performance index (MPI) is a quantitative measure of combined left ventricular systolic and diastolic function. We sought to characterize the changes in MPI during LDDE in control subjects and patients with MI, and to describe the relation of these changes to changes in regional systolic function.

METHODS

MPI was obtained at rest and during LDDE (10 microg/kg/min) in 25 healthy volunteers (group 1) and 50 patients with a recent MI. Patients were divided into two subsets; those with (n = 23; group 2A) and those without (n = 27; group 2B) a contractile reserve defined as an improvement of wall motion in more than two contiguous infarct-zone segments during LDDE. DeltaMPI was defined as the change from rest to LDDE.

RESULTS

MPI decreased significantly during LDDE in groups 1 and 2A, whereas MPI increased in group 2B (DeltaMPI = 0.12 +/- 0.04 and 0.10 +/- 0.08 vs -0.03 +/- 0.08, P <.0001). On multivariate analysis, Deltawall-motion score index predicted DeltaMPI (beta = 0.65, P <.0001) independently of age, sex, and the dobutamine-induced change in heart rate and systolic blood pressure.

CONCLUSIONS

Data suggest that the change in MPI during LDDE may provide a simple and quantitative measure of overall left ventricular functional reserve in patients with a recent MI.

Validation of the myocardial performance index by echocardiography in mice: a noninvasive measure of left ventricular function

BACKGROUND

The myocardial performance index (MPI) is a Doppler-based measure of left ventricular (LV) function. It is noninvasive, independent of LV shape, and does not require dimensional measurements. However, it has never been validated in mice.

METHODS

A total of 29 anesthetized mice with LV pressure catheters underwent echocardiography (2-dimensional, M-mode, and Doppler) at baseline and during manipulations of beta-adrenergic tone, temperature, preload, and afterload. The maximum derivative of LV pressure with respect to time (dP/dt(max)) was compared with MPI, fractional shortening (FS), mean velocity of circumferential fiber shortening, and the FS/MPI ratio.

RESULTS

MPI (baseline 0.44 +/- 0.07) correlated strongly with dP/dt(max) (R = -.779, P <.001), as did FS and mean velocity of circumferential fiber shortening. MPI differed significantly with contractility, preload, and afterload manipulation. FS/MPI showed the best correlation with dP/dt(max).

CONCLUSIONS

MPI strongly correlates with dP/dt(max) over a range of hemodynamic conditions in mice. It can be used as a noninvasive index of LV function in this species.