Acute Left Ventricular Dynamic Effects of Primary Percutaneous Coronary Intervention

Early effect of different bifurcation techniques on left ventricular mechanics in elective percutaneous coronary intervention

BACKGROUND

Bifurcation lesions are prevalent amongst patients with symptomatic coronary artery disease subjected to percutaneous coronary intervention (PCI). Recent consensus commends a conservative (provisional) approach when managing the side branch. Here, the aim was to explore the immediate impact of different bifurcation techniques (one stent and two stent strategies) on left ventricular LV) myocardial functions using speckle tracking echocardiography in patients subjected to elective PCI. Sixty two consecutive patients diagnosed with coronary bifurcation lesion (CBL) were enrolled. Patients were categorized into: one-stent strategy (Provisional group, n = 44) and a two-stent strategy (TAP, DK crush, or Culotte technique, n = 18), based on the coronary bifurcation site, angle, side branch diameter and Medina classification. LVEF%, regional and global longitudinal strain (GLS), and E/E' were measured before and within 24 h post PCI.

RESULTS

In both provisional and 2- stent technique, the mitral inflow velocities and mitral annular velocities showed improvement with significant reduction in E/e' (P < 0.03 and P < 0.001) respectively while LVEF% did not change. There were no significant changes in any other echo parameters post PCI. In provisional group, there were significant improvements in LAD (P < 0.001), RCA (P < 0.01) territories and GLS (P < 0.01). Δ LAD was expressively higher (34.5%) compared with Δ LCX (9.6%) and ΔRCA (25.4%), P < 0.001, P < 0.01 respectively. In the 2-stent technique group, there were significant improvements in peak longitudinal strain of LAD territory (P < 0.01), RCA territory (P < 0.01) and GLS (P < 0.01) respectively. Δ LAD territory was significantly higher in provisional group in comparison with the 2- stent technique group. Δ GLS was correlated inversely to Gensini score in provisional group and to the number of vessel diseased in 2-stent technique group.

CONCLUSION

PCI of the bifurcation lesion positively impact myocardial function. Both bifurcation techniques improve LV mechanical properties using 2D strain imaging while LV EF% remains unchanged.

Benefits of Intra-Aortic Balloon Pump Support in Patients with Postcardiotomy Shock Requiring Venoarterial Extracorporeal Membrane Oxygenation

Background: The benefit of the combined use of an intra-aortic balloon pump (IABP) and venoarterial extracorporeal membrane oxygenation (VA-ECMO) for postcardiotomy shock remains unclear. We aimed to analyse the potential benefits and safety of combining these two devices. Methods: We enrolled 200 patients treated with either VA-ECMO only or in combination with IABP (ECMO-I group) between January 2012 and January 2021. To adjust the patients’ backgrounds, we used propensity score matching for additional analyses, resulting in 57 pairs. The primary endpoint was 30-day survival. Secondary endpoints included successful weaning and complication rates. We also analysed hemodynamic parameters in both groups. Results: After propensity score matching, 30-day survival was better in the ECMO-I group (log-rank p = 0.004). The ECMO-I and ECMO-only groups differed regarding the secondary endpoints, including successful weaning (50.9% and 26.3%, respectively; p = 0.012) and the need for continuous renal replacement therapy (28.1% and 50.9%, p = 0.021). Complication rates were not statistically different between the two groups. Conclusion: Compared to VA-ECMO alone, the combined use of VA-ECMO and IABP is beneficial regarding 30-day survival in selected patients with postcardiotomy shock; successful ECMO weaning and freedom from renal replacement therapy is more common in patients supported with VA-ECMO plus IABP.

Effects of deferred versus immediate stenting on left ventricular function in patients with ST elevation myocardial infarction

BACKGROUND

Previous studies have shown conflicting results on the benefits of deferred stenting (DS) in infarct size and the incidence of microvascular obstruction in patients with ST elevation myocardial infarction (STEMI). However, effect of DS on left ventricular (LV) function was not known. We aimed to evaluate whether DS improve LV function and relevant clinical outcomes after STEMI, using follow-up data from the INNOVATION study (NCT02324348).

METHODS

In total, 114 patients were randomly assigned to DS group or immediate stenting (IS) group at a 1:1 ratio. LV functional remodeling indices and MACE (major adverse cardiac events: a composite of death, non-fatal MI, unplanned target vessel revascularization, or hospitalization due to heart failure) were compared between DS and IS groups.

RESULTS

Serial echocardiographic analyses were completed in 89 subjects (78%). There were no significant changes in LV volume in either group. While LV ejection fraction and wall motion score index (WMSI) improved in both groups during follow-up, the increments were not statistically different between the 2 groups (4.3 ± 8.2 vs 3.2 ± 7.1, P = .504 for ΔLV ejection fraction; -0.16 ± 0.25 vs -0.16 ± 0.25, P = .99 for ΔWMSI). However, E/e'' was decreased and e' was increased only in the DS group (-3.31 ± 5.60 vs -0.46 ± 3.10, P = .005 for ΔE/e'; 0.77 ± 1.71 vs -0.22 ± 1.64, P = .009 for Δe'). The incidence of major adverse cardiac events was numerically lower in the DS group than in the IS group without a statistical significance at 1-year follow-up.

CONCLUSIONS

Routine DS improved LV diastolic function but not systolic function compared with IS in patients with STEMI.

Hemodynamic Validation of the E/e' Ratio as a Measure of Left Ventricular Filling Pressure in Patients With Non-ST Elevation Myocardial Infarction

The E/e' ratio has an established role in the assessment of left ventricular filling pressure (LVFP) in stable patients, but its accuracy in acute myocardial ischemia is less well established. The aim of this study was to validate the relation between the E/e' ratio and invasively measured LVFP in patients with non-ST elevation myocardial infarction (NSTEMI). A total of 120 unselected patients with NSTEMI underwent cardiac catheterization with measurement of left ventricular end-diastolic pressure (LVEDP; elevated ≥15 mm Hg) and Doppler echocardiography with either simultaneous (n = 30) or same-day (n = 90) measurement of E/e'. Patients were aged 64.1 ± 11.8 years, 72% were male and mean left ventricular ejection fraction was 48.0 ± 20.9%. Septal, lateral, and average E/e' ratios all showed a significant correlation with LVEDP (Pearson's r: 0.42, 0.43, 0.48, respectively [all p <0.001]). Receiver operating characteristics curves showed an area under the curve of 0.72, 0.72, and 0.75 (all p <0.001) for septal, lateral, and average E/e', respectively. The sensitivity, specificity, positive (PPV), and negative (NPV) predictive values for the guideline-recommended threshold of average E/e' >14 for elevated LVEDP was 27%, 93%, 79%, and 44%, respectively. Utilizing lower E/e' boundaries of 6, 7, and 8 for lateral, average, and medial E/e', respectively, improved the NPV to ≥80% for each parameter. In conclusion, the E/e' ratio is a robust measure of LVFP during acute NSTEMI using upper and lower thresholds to achieve a high PPV and NPV, respectively, with the use of adjunctive guideline-recommend measures required in patients with nonconclusive E/e'.

Utilization of Percutaneous Mechanical Circulatory Support Devices in Cardiogenic Shock Complicating Acute Myocardial Infarction and High-Risk Percutaneous Coronary Interventions

Given the tremendous progress in interventional cardiology over the last decade, a growing number of older patients, who have more comorbidities and more complex coronary artery disease, are being considered for technically challenging and high-risk percutaneous coronary interventions (PCI). The success of performing such complex PCI is increasingly dependent on the availability and improvement of mechanical circulatory support (MCS) devices, which aim to provide hemodynamic support and left ventricular (LV) unloading to enable safe and successful coronary revascularization. MCS as an adjunct to high-risk PCI may, therefore, be an important component for improvement in clinical outcomes. MCS devices in this setting can be used for two main clinical conditions: patients who present with cardiogenic shock complicating acute myocardial infarction (AMI) and those undergoing technically complex and high-risk PCI without having overt cardiogenic shock. The current article reviews the advancement in the use of various devices in both AMI complicated by cardiogenic shock and complex high-risk PCI, highlights the available hemodynamic and clinical data associated with the use of MCS devices, and presents suggestive management strategies focusing on appropriate patient selection and optimal timing and support to potentially increase the clinical benefit from utilizing these devices during PCI in this high-risk group of patients.

Beyond Reperfusion: Acute Ventricular Unloading and Cardioprotection During Myocardial Infarction

Heart failure is a major cause of morbidity and mortality around the world, and myocardial infarction is its leading cause. Myocardial infarction destroys viable myocardium, and this dead tissue is replaced by a non-contractile scar that results in impaired cardiac function and a significantly increased likelihood of the patient developing heart failure. Limiting infarct scar size has been the target of pre-clinical and clinical investigations for decades. However, beyond reperfusion, few therapies have translated into the clinic that limit its formation. New approaches are needed. This review will focus on new clinical and pre-clinical data demonstrating that acute ventricular unloading prior to reperfusion by means of percutaneous left ventricular support devices reduces ischemia-reperfusion injury and limits infarct scar size. Emphasis will be given to summarizing our current mechanistic understanding of this new therapeutic approach to treating myocardial infarction.

Acute effect of primary PCI on diastolic dysfunction recovery in anterior wall STEMI - A non-invasive evaluation by echocardiography

BACKGROUND

It is well established fact that acute coronary occlusion leads to diastolic dysfunction, followed by systolic dysfunction when myonecrosis occur. It is also proven that primary percutaneous coronary intervention (PPCI) is an excellent therapy for ST elevation myocardial infarction (STEMI) to improve outcomes. However there is a paucity of information on efficacy of PPCI in improving diastolic function. Evaluation of the role of PPCI in improving diastolic dysfunction is required.

METHODS

61 patients with first anterior wall STEMI who underwent PPCI to left anterior descending artery were included. Echocardiographic evaluation was performed within 24 h of PPCI and then on day 15, 3 months and 6 months after PPCI. We evaluated the prevalence of diastolic dysfunction after PPCI and its recovery during 6 months along with effect of duration of chest pain on diastolic function.

RESULTS

54.1% of patients had diastolic dysfunction after PPCI whereas it was only 21.3% after 6 months (p value < 0.001). Diastolic function indices like deceleration time, isovolumic relaxation time, E wave, A wave, E/A ratio, left atrial volume and index improved statistically from baseline to 6 months except mitral E/e' ratio. As time required to achieve reperfusion increases (chest pain duration and D to B time) the incidence of residual diastolic dysfunction also increases (p value < 0.001). Patients with TIMI flow < III had more diastolic dysfunction (p value < 0.001).

CONCLUSIONS

Primary PCI improves diastolic dysfunction in patients with anterior wall STEMI over a period of 6 months. Time to achieve reperfusion and effectiveness of reperfusion have significant effect on diastolic dysfunction.

Effect of elective percutaneous coronary intervention of left anterior descending coronary artery on regional myocardial function using strain imaging

BACKGROUND

Percutaneous coronary intervention (PCI) is a commonly used procedure for revascularization, however the impairment of regional myocardial function in patients with stable coronary artery disease (CAD) has not been well characterized, our study aimed to assess the improvement of left ventricular (LV) systolic function after elective PCI of the left anterior descending artery (LAD) using strain and strain rate imaging techniques.

MATERIALS AND METHODS

The study included 30 patients (aged 56.8 ± 6.6 years, 66.7% males) presented with stable CAD on optimal medical therapy, and recommended for elective PCI to LAD, all patients included in the study had a normal LV wall motions, and normal LV systolic function. Tissue Doppler imaging (TDI) was done before PCI, immediately, and three months post PCI. The peak systolic longitudinal strain (PSLS), and peak systolic strain rate (PSSR) were measured and averaged for the 6 LAD segments (the basal, mid, and apical segments of the anterior wall, the basal, mid anteroseptal, and the apicoseptal segments), 15 healthy control subjects were included as a control group.

RESULTS

The average PSLS and PSSR of the ischemic segments were significantly lower in patients compared to control in the ischemic segments, and significantly increased 3 months post PCI but not immediately post PCI. Using the ROC curve a cutoff value of -13.69% for PSLS can detect regional ischemia with a sensitivity 93.3% and a specificity of 80%.

CONCLUSIONS

TDI derived strain and strain rate can detect resting regional myocardial dysfunction in presence of preserved LV systolic function, and can assess the improvement of regional myocardial function after successful elective PCI in patients with stable CAD.

Increased pulse wave transit time after percutaneous coronary intervention procedure in CAD patients

Pulse wave transit time (PWTT) has been widely used as an index in assessing arterial stiffness. Percutaneous coronary intervention (PCI) is usually applied to the treatment of coronary artery disease (CAD). Research on the changes in PWTT caused by PCI is helpful for understanding the impact of the PCI procedure. In addition, effects of stent sites and access sites on the changes in PWTT have not been explored. Consequently, this study aimed to provide this information. The results showed that PWTT significantly increased after PCI (p < 0.01) while the standard deviation (SD) of PWTT time series had no statistically significant changes (p = 0.60) between before and after PCI. Significantly increased PWTT was found in the radial access group (p < 0.01), while there were no significant changes in the femoral access group (p > 0.4). Additionally, PWTT in the left anterior descending (LAD) group significantly increased after PCI (p < 0.01), but the increase that was found in the right coronary artery (RCA) group was not significant (p > 0.1). Our study indicates that arterial elasticity and left ventricular functions can benefit from a successful PCI procedure, and the increase of peripheral PWTT after PCI can help to better understand the effectiveness of the procedure.

IABP: history-evolution-pathophysiology-indications: what we need to know

Treatment with the intraaortic balloon pump (IABP) is the most common form of mechanical support for the failing heart. Augmentation of diastolic pressure during balloon inflation contributes to the coronary circulation and the presystolic deflation of the balloon reduces the resistance to systolic output. Consequently, the myocardial work is reduced. The overall effect of the IABP therapy is an increase in the myocardial oxygen supply/demand ratio and thus in endocardial viability.

This is an overall synopsis of what we need to know regarding IABP. Furthermore, this review article attempts to systematically delineate the pathophysiology linked with the hemodynamic consequences of IABP therapy. The authors also look at the future of the use of the balloon pump and conclude that the positive multi-systemic hemodynamic regulation during IABP treatment should further justify its use.

2015 SCAI/ACC/HFSA/STS Clinical Expert Consensus Statement on the Use of Percutaneous Mechanical Circulatory Support Devices in Cardiovascular Care (Endorsed by the American Heart Association, the Cardiological Society of India, and Sociedad Latino Americana de Cardiologia Intervencion; Affirmation of Value by the Canadian Association of Interventional Cardiology-Association Canadienne de Cardiologie d'intervention)

Although historically the intra-aortic balloon pump has been the only mechanical circulatory support device available to clinicians, a number of new devices have become commercially available and have entered clinical practice. These include axial flow pumps, such as Impella(®); left atrial to femoral artery bypass pumps, specifically the TandemHeart; and new devices for institution of extracorporeal membrane oxygenation. These devices differ significantly in their hemodynamic effects, insertion, monitoring, and clinical applicability. This document reviews the physiologic impact on the circulation of these devices and their use in specific clinical situations. These situations include patients undergoing high-risk percutaneous coronary intervention, those presenting with cardiogenic shock, and acute decompensated heart failure. Specialized uses for right-sided support and in pediatric populations are discussed and the clinical utility of mechanical circulatory support devices is reviewed, as are the American College of Cardiology/American Heart Association clinical practice guidelines.

Aggressive hydraTion in patients with ST-Elevation Myocardial infarction undergoing Primary percutaneous coronary intervention to prevenT contrast-induced nephropathy (ATTEMPT): Study design and protocol for the randomized, controlled trial, the ATTEMPT, RESCIND 1 (First study for REduction of contraSt-induCed nephropathy followINg carDiac catheterization) trial

Adequate hydration is recommended for acute ST-elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI) to prevent contrast-induced nephropathy (CIN). However, the optimal hydration regimen has not been well established in these high-risk patients. The objective of this study is to evaluate the efficacy of a preprocedural loading dose plus postprocedural aggressive hydration with normal saline guided by the left ventricular end-diastolic pressure (LVEDP) compared with general hydration for CIN prevention. The ATTEMPT study is a multicenter, open-label, investigator-driven, randomized controlled trial in China. Approximately 560 patients with STEMI undergoing primary PCI will be randomized (1:1) to receive either periprocedural general hydration (control group) or aggressive hydration (treatment group). Patients in the control group receive periprocedural general hydration with ≤500 mL normal saline (within 6 hours) at a normal rate (0.5 or 1 mL/kg · h). Patients in the treatment group receive a preprocedural loading dose (125/250 mL) of normal saline within 30 minutes and intravenous hydration at a normal rate until LVEDP is available, followed by postprocedural aggressive hydration guided by LVEDP for 4 hours and then continuous intravascular hydration at the normal rate until 24 hours after PCI. The primary end point is CIN, defined as a >25% or 0.5-mg/dL increase in serum creatinine from baseline during the first 48 to 72 hours after procedure. The ATTEMPT study has the potential to identify optimal hydration regimens for STEMI patients undergoing PCI.

Low tidal volume ventilation ameliorates left ventricular dysfunction in mechanically ventilated rats following LPS-induced lung injury

Background

High tidal volume ventilation has shown to cause ventilator-induced lung injury (VILI), possibly contributing to concomitant extrapulmonary organ dysfunction. The present study examined whether left ventricular (LV) function is dependent on tidal volume size and whether this effect is augmented during lipopolysaccharide(LPS)-induced lung injury.

Methods

Twenty male Wistar rats were sedated, paralyzed and then randomized in four groups receiving mechanical ventilation with tidal volumes of 6 ml/kg or 19 ml/kg with or without intrapulmonary administration of LPS. A conductance catheter was placed in the left ventricle to generate pressure-volume loops, which were also obtained within a few seconds of vena cava occlusion to obtain relatively load-independent LV systolic and diastolic function parameters. The end-systolic elastance / effective arterial elastance (Ees/Ea) ratio was used as the primary parameter of LV systolic function with the end-diastolic elastance (Eed) as primary LV diastolic function.

Results

Ees/Ea decreased over time in rats receiving LPS (p = 0.045) and high tidal volume ventilation (p = 0.007), with a lower Ees/Ea in the rats with high tidal volume ventilation plus LPS compared to the other groups (p < 0.001). Eed increased over time in all groups except for the rats receiving low tidal volume ventilation without LPS (p = 0.223). A significant interaction (p < 0.001) was found between tidal ventilation and LPS for Ees/Ea and Eed, and all rats receiving high tidal volume ventilation plus LPS died before the end of the experiment.

Conclusions

Low tidal volume ventilation ameliorated LV systolic and diastolic dysfunction while preventing death following LPS-induced lung injury in mechanically ventilated rats. Our data advocates the use of low tidal volumes, not only to avoid VILI, but to avert ventilator-induced myocardial dysfunction as well.

Closing the loop: modelling of heart failure progression from health to end-stage using a meta-analysis of left ventricular pressure-volume loops

Introduction

The American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for the classification of heart failure (HF) are descriptive but lack precise and objective measures which would assist in categorising such patients. Our aim was two fold, firstly to demonstrate quantitatively the progression of HF through each stage using a meta-analysis of existing left ventricular (LV) pressure-volume (PV) loop data and secondly use the LV PV loop data to create stage specific HF models.

Methods and Results

A literature search yielded 31 papers with PV data, representing over 200 patients in different stages of HF. The raw pressure and volume data were extracted from the papers using a digitising software package and the means were calculated. The data demonstrated that, as HF progressed, stroke volume (SV), ejection fraction (EF%) decreased while LV volumes increased. A 2-element lumped parameter model was employed to model the mean loops and the error was calculated between the loops, demonstrating close fit between the loops. The only parameter that was consistently and statistically different across all the stages was the elastance (Emax).

Conclusions

For the first time, the authors have created a visual and quantitative representation of the AHA/ACC stages of LVSD-HF, from normal to end-stage. The study demonstrates that robust, load-independent and reproducible parameters, such as elastance, can be used to categorise and model HF, complementing the existing classification. The modelled PV loops establish previously unknown physiological parameters for each AHA/ACC stage of LVSD-HF, such as LV elastance and highlight that it this parameter alone, in lumped parameter models, that determines the severity of HF. Such information will enable cardiovascular modellers with an interest in HF, to create more accurate models of the heart as it fails.

Prognostic implications of left ventricular end-diastolic pressure during primary percutaneous coronary intervention for ST-segment elevation myocardial infarction: Findings from the Assessment of Pexelizumab in Acute Myocardial Infarction study

BACKGROUND

Left ventricular end-diastolic pressure (LVEDP) is frequently measured during primary percutaneous coronary intervention (PCI). However, little is known of this measurement's utility in predicting outcomes or informing treatment decisions. We sought to determine the prognostic value of LVEDP measured during primary PCI for ST-segment elevation myocardial infarction (STEMI).

METHODS

We studied 1,909 (33.2%) of 5,745 STEMI patients in whom LVEDP was measured during primary PCI in the APEX-AMI trial. Cox regression analysis was used to evaluate whether LVEDP was an independent predictor of mortality and the composite of death, cardiogenic shock, or congestive heart failure (CHF) at 90 days.

RESULTS

The median (25th, 75th percentiles) LVEDP level was 22 mm Hg (16, 29); compared with patients with LVEDP ≤ 22 mm Hg, those with LVEDP > 22 mm Hg had higher rates of CHF (7.3% vs 3.1%, P < .001), cardiogenic shock (4.6% vs 1.7%, P < .001), and death (4.1% vs 2.2%, P = .014) at 90 days. After multivariable adjustment, LVEDP was associated with increased risk of mortality through 90 days (adjusted hazard ratio 1.22, 95% CI 1.02-1.46, per 5-mmHg increase, P = .044) and the composite of death, cardiogenic shock, or CHF within the first 2 days (adjusted hazard ratio 1.40, 95% CI 1.23-1.59, per 5-mm Hg increase, P < .001), but not from day 3 to 90 (P = .25).

CONCLUSIONS

Left ventricular end-diastolic pressure measured during primary PCI for STEMI is an independent predictor of inhospital and longer term cardiovascular outcomes. Measuring LVEDP may be useful to stratify patient risk and guide postinfarct treatment.

Cardioprotective effects of exenatide in patients with ST-segment-elevation myocardial infarction undergoing primary percutaneous coronary intervention: results of exenatide myocardial protection in revascularization study

OBJECTIVE

Experimental evidence suggests that exenatide, a glucagon-like peptide 1 receptor analogue, has significant cardiovascular protective effects in various conditions. We examined whether routine use of exenatide at the time of primary percutaneous coronary intervention would reduce infarct size in patients with ST-segment-elevation myocardial infarction.

APPROACH AND RESULTS

Fifty-eight patients with ST-segment-elevation myocardial infarction and thrombolysis in myocardial infarction flow 0 were enrolled in the study and randomly assigned to receive either exenatide or placebo (saline) subcutaneously. Infarct size was assessed by measuring the release of creatine kinase-MB and troponin I during 72 hours and by performing cardiac magnetic resonance imaging at 1 month after infarction. Routine and speckle tracking echocardiography was performed at initial presentation and at 3 days and 6 months after primary percutaneous coronary intervention. The exenatide and control groups had similar results with respect to ischemia time, demographic characteristics, and ejection fraction before primary percutaneous coronary intervention. The releases of creatine kinase-MB and troponin I were significantly reduced in the exenatide group. In 58 patients evaluated with cardiac magnetic resonance, the absolute mass of delayed hyperenhancement was significantly reduced in the exenatide group as compared with the control group (12.8±11.7 versus 26.4±11.6 g; P<0.01). At 6 months, the exenatide group showed a significantly lower value of E/E' with improved strain parameters. No significant adverse effects of exenatide administration were detected.

CONCLUSIONS

In patients with ST-segment-elevation myocardial infarction, adjunctive exenatide therapy with primary percutaneous coronary intervention was associated with reduction of infarct size and improvement of subclinical left ventricular function.

Coronary microcirculatory dysfunction is associated with left ventricular dysfunction during follow-up after STEMI

BACKGROUND

Coronary microvascular resistance is increased after primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI), which may be related in part to changed left ventricular (LV) dynamics. Therefore we studied the coronary microcirculation in relation to systolic and diastolic LV function after STEMI.

METHODS

The study cohort consisted of 12 consecutive patients, all treated with primary PCI for a first anterior wall STEMI. At 4 months, we assessed pressure-volume loops. Subsequently, we measured intracoronary pressure and flow velocity and calculated coronary microvascular resistance. Infarct size and LV mass were assessed using magnetic resonance imaging.

RESULTS

Patients with an impaired systolic LV function due to a larger myocardial infarction showed a higher baseline average peak flow velocity (APV) than the other patients (26 ± 7 versus 17 ± 5 cm/s, p = 0.003, respectively), and showed an impaired variable microvascular resistance index (2.1 ± 1.0 versus 4.1 ± 1.3 mmHg cm(-1)∙s(-1), p = 0.003, respectively). Impaired diastolic relaxation time was inversely correlated with hyperaemic APV (r = -0.56, p = 0.003) and positively correlated with hyperaemic microvascular resistance (r = 0.48, p = 0.01). LV dilatation was associated with a reduced variable microvascular resistance index (r = 0.78, p = 0.006).

CONCLUSION

A larger anterior myocardial infarction results in impaired LV performance associated with reduced coronary microvascular resistance variability, in particular due to higher coronary blood flow at baseline in these compromised left ventricles.