Coronary physiology thresholds associated with microvascular obstruction in myocardial infarction

OBJECTIVES

To ascertain whether invasive assessment of coronary physiology soon after recanalisation of the culprit artery by primary percutaneous coronary intervention is associated with the development of microvascular obstruction by cardiac magnetic resonance in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

Between November 2020 and December 2021, 102 consecutive patients were prospectively enrolled in five tertiary centres in Italy. Coronary flow reserve (CFR) and index of microvascular resistance (IMR) were measured in the culprit vessel soon after successful primary percutaneous coronary intervention. Optimal cut-off points of IMR and CFR to predict the presence of microvascular obstruction were estimated, stratifying the population accordingly in four groups. A comparison with previously proposed stratification models was carried out.

RESULTS

IMR>31 units and CFR≤1.25 yielded the best accuracy. Patients with IMR>31 and CFR≤1.25 exhibited higher microvascular obstruction prevalence (83% vs 38%, p<0.001) and lower left ventricular ejection fraction (45±9% vs 52±9%, p=0.043) compared with those with IMR≤31 and CFR>1.25, and lower left ventricular ejection fraction compared with patients with CFR≤1.25 and IMR≤31 (45±9% vs 54±7%, p=0.025). Infarct size and area at risk were larger in the former, compared with other groups.

CONCLUSIONS

IMR and CFR are associated with the presence of microvascular obstruction in STEMI. Patients with an IMR>31 units and a CFR≤1.25 have higher prevalence of microvascular obstruction, lower left ventricular ejection fraction, larger infarct size and area at risk.

TRIAL REGISTRATION NUMBER

NCT04677257.

Coronary Sinus Narrowing Improves Coronary Microcirculation Function in Patients With Refractory Angina: A Multicenter Prospective INROAD Study

BACKGROUND

The underlying mechanisms responsible for the clinical benefits following coronary sinus narrowing and pressure elevation remain unclear. The present study aims to investigate whether coronary sinus narrowing improves the indexes of coronary microcirculatory function.

METHODS

Patients with refractory angina who had a clinical indication for reducer implantation underwent invasive physiological assessments before and 4 months after the procedure. The primary outcome was the change in the values of the index of microcirculatory resistance. Secondary end points included changes in coronary flow reserve and the resistive resistance ratio values. Angina status was assessed with the Canadian Cardiology Society class and the Seattle Angina Questionnaire.

RESULTS

Twenty-four patients with a history of obstructive coronary artery disease and prior coronary revascularization (surgical and percutaneous) treated with reducer implantation were enrolled, and 21 of them (87%) underwent repeated invasive coronary physiological assessment after 4 months. The index of microcirculatory resistance values decreased from 33.35±19.88 at baseline to 15.42±11.36 at 4-month follow-up (P<0.001; mean difference, -17.90 [95% CI, -26.16 to -9.64]). A significant (≥20% from baseline) reduction of the index of microcirculatory resistance was observed in 15 (71.4% [95% CI, 47.8%-88.7%]) patients. The number of patients with abnormal index of microcirculatory resistance (≥25) decreased from 12 (57%) to 4 (19%; P=0.016). Coronary flow reserve increased from 2.46±1.52 to 4.20±2.52 (mean difference, 1.73 [95% CI, 0.51-2.96]). Similar findings were observed for resistive resistance ratio values. Overall, 16 patients (76.1%) had an improvement of 1 Canadian Cardiology Society class. Seattle Angina Questionnaire summary score increase of around 3 points (3.01 [95% CI, 1.39-4.61]).

CONCLUSIONS

Coronary sinus reduction implantation is associated with a significant improvement in the parameters of coronary microcirculatory function. These findings provide insights into the improvement of angina symptoms and may have implications for the treatment of coronary microvascular dysfunction.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05174572.

Left Ventricular End-Diastolic Pressure for the Prediction of Contrast-Induced Nephropathy and Clinical Outcomes in Patients With ST-Elevation Myocardial Infarction Who Underwent Primary Percutaneous Intervention (the ELEVATE Study)

Contrast-induced nephropathy (CIN) is an important complication of percutaneous coronary intervention (PCI). We investigated whether left ventricular end-diastolic pressure (LVEDP) in patients who underwent PCI might be additive to current risk stratification of CIN. Data from consecutive patients who underwent primary PCI for ST-elevation myocardial infarction between 2013 and 2018 at Western Health in Victoria, Australia were analyzed. CIN was defined as a 25% increase in serum creatinine from baseline or 44 µmol/L increase in absolute value within 48 hours of contrast administration. Compared with patients without CIN (n = 455, 93%), those who developed CIN (n = 35, 7%) were older (64 vs 58 years, p = 0.006), and had higher peak creatine kinase (2,862 [1,258 to 3,952] vs 1,341 U/L [641 to 2,613], p = 0.02). The CIN group had higher median LVEDP (30 [21-33] vs 25 mm Hg [20-30], p = 0.013) and higher median Mehran risk score (MRS) (5 [2-8] vs 2 [1-5], p <0.001). Patients with CIN had more in-hospital major adverse cardiovascular and cerebrovascular events (composite end point of death, new or recurrent myocardial infarction or stent thrombosis, target vessel revascularization or stroke) (23% vs 8.6%, p = 0.01), but similar 30-day major adverse cardiovascular and cerebrovascular events (20% vs 15%, p = 0.46). An LVEDP >30 mm Hg independently predicted CIN (odds ratio 3.4, 95% confidence interval 1.46 to 8.03, p = 0.005). The addition of LVEDP ≥30 mm Hg to MRS marginally improved risk prediction for CIN compared with MRS alone (area-under-curve, c-statistic = 0.71 vs c-statistic = 0.63, p = 0.08). In conclusion, elevated LVEDP ≥30 mm Hg during primary PCI was an independent predictor of CIN in patients treated for ST-elevation myocardial infarction. The addition of LVEDP to the MRS may improve risk prediction for CIN.

The Additive Effect of Left Ventricular Filling Pressure and Renal Function on Long-Term Prognosis of High-Risk Patients Undergoing Coronary Angiography

INTRODUCTION

Impaired relaxation is the earliest manifestation of ischemic cascade. Risk factors and renal function abnormalities are associated with coronary disease and diastolic dysfunction as well. We aimed to study the association of noninvasive assessment of left ventricular filling pressures and renal function with mortality in high-risk patients undergoing coronary angiography.

PATIENTS AND METHODS

An observational prospective study of 564 consecutive patients undergoing coronary angiography was conducted. The median follow-up was 2,293 days. Patients were categorized into 2 groups according to presence of significant diastolic dysfunction: group 1, 382 patients, with normal and group 2, 182 patients, with elevated filling pressure. Renal insufficiency was determined as calculated glomerular filtration rate <60 mL/min. Patients demographic, clinical, echocardiography, laboratory, and angiographic data were prospectively collected.

RESULTS

Fifty-three percent of patients underwent angiography due to acute coronary syndrome (ACS), 85.5% had coronary artery disease, 53.4% had reduced (<50%) left ventricular ejection fraction (LVEF), and 47.4% had abnormal renal function. The mortality during the follow-up period was 30.0%. Patients with elevated filling pressure had significantly higher mortality (50.5% vs. 20.2%, p < 0.0001). Impaired renal failure as well, was associated with higher mortality (48% vs. 15%, p < 0.001). The association remained significant in subgroups of patients with and without ACS and reduced and preserved LVEF. In Cox regression model which combined elevated filling pressure, renal insufficiency, age, diabetes mellitus, hypertension, presence of atrial fibrillation, LVEF, and anemia, elevated filling pressure and renal function impairment were independently associated with higher mortality (HR: 3.717, CI: 1.623-8.475, p < 0.0001 and HR: 0.972, CI: 0.958-0.985, p = 0.0001, respectively). There was an incremental prognostic value of elevated filling pressures and renal function impairment on mortality.

CONCLUSIONS

Advanced diastolic dysfunction and impaired renal function are signals toward worse outcomes and are associated with mortality in high-risk patients undergoing coronary angiography.

Management of temporary mechanical circulatory support devices in cath-lab and cardiac intensive care unit

Different temporary mechanical circulatory support (tMCS) devices are available and can be used to maintain end-organ perfusion while reducing cardiac work and myocardial oxygen demand. tMCS can provide support to the right ventricle, left ventricle, or both, and its use can be considered in emergency situations such as cardiogenic shock or in elective procedures such as high-risk percutaneous coronary intervention to prevent haemodynamic deterioration. Invasive and, most importantly, non-invasive haemodynamic parameters should be taken into account when choosing the type of tMCS device and its initiation and weaning timing, determining the need for a device upgrade, and screening for complications. In this context, ultrasound tools, specifically echocardiography, can provide important data. This review aims to provide a description of the different tMCS devices, the invasive and non-invasive tools and parameters to guide their management, and their advantages and drawbacks.

Ability of a novel shock index that incorporates invasive hemodynamics to predict mortality in patients with ST-elevation myocardial infarction

OBJECTIVE

To determine whether the use of invasively measured hemodynamics improves the prognostic ability of a shock index (SI).

BACKGROUND

SI such as Admission-SI, Age-SI, Modified SI (MSI), and Age-MSI predict short-term mortality in ST-elevation myocardial infarction (STEMI).

METHODS

Single-center study of 510 patients who underwent primary percutaneous coronary intervention. STEMI SI was defined as age × heart rate (HR) divided by coronary perfusion pressure (CPP).

RESULTS

The mean age was 62 ± 14 years, 66% were males with hypertension (69%), tobacco use (38%), diabetes (28%) and chronic kidney disease (6%). The mean HR, systolic blood pressure (SBP), and CPP were 81 ± 18 bpm, 124 ± 28 mmHg, and 52.8 ± 16.3 mmHg, respectively. Patients with STEMI SI ≥182 (n = 51) were more likely to experience a cardiac arrest in the catheterization laboratory (9.8% vs. 2.0%; p = .001), require mechanical circulatory support (47.1% vs. 8.5%; p < .0001) and be treated with vasopressors (56.9% vs. 10.7%; p < .0001) compared to STEMI SI < 182 (n = 459). After multivariate adjustment, patients with STEMI SI ≥182 were 10, 10.1 and 4.8 times more likely to die during hospitalization, at 30 days and at 5 years, respectively. The C statistic of STEMI SI was 0.870, similar to GRACE score (AUC = 0.902; p = .29) and TIMI STEMI score (AUC = 0.895; p = .36).

CONCLUSION

STEMI SI is an easy to calculate risk score that identifies STEMI patients at high risk of in-hospital death.

Door-to-unload: left ventricular unloading before reperfusion in ST-elevation myocardial infarction

ST-elevation myocardial infarction treatment in the modern era has focused on minimizing time of ischemia by reducing door-to-balloon time to limit infarct size and improve survival. Although there have been significant improvements in minimizing time to coronary reperfusion, the incidence of heart failure following a myocardial infarction has remained high. Preclinical studies have shown that unloading the left ventricle for 30 min prior to coronary reperfusion can reduce infarct size and promote myocardial recovery. The DTU-STEMI randomized prospective trial will test the hypothesis that left ventricular unloading for at least 30 min prior to coronary reperfusion will improve infarct size and heart failure-related events as compared with the current standard of care.

Risk Stratification Guided by the Index of Microcirculatory Resistance and Left Ventricular End-Diastolic Pressure in Acute Myocardial Infarction

BACKGROUND

The index of microcirculatory resistance (IMR) of the infarct-related artery and left ventricular end-diastolic pressure (LVEDP) are acute, prognostic biomarkers in patients undergoing primary percutaneous coronary intervention. The clinical significance of IMR and LVEDP in combination is unknown.

METHODS

IMR and LVEDP were prospectively measured in a prespecified substudy of the T-TIME clinical trial (Trial of Low Dose Adjunctive Alteplase During Primary PCI). IMR was measured using a pressure- and temperature-sensing guidewire following percutaneous coronary intervention. Prognostically established thresholds for IMR (>32) and LVEDP (>18 mm Hg) were predefined. Contrast-enhanced cardiovascular magnetic resonance imaging (1.5 Tesla) was acquired 2 to 7 days and 3 months postmyocardial infarction. The primary end point was major adverse cardiac events, defined as cardiac death/nonfatal myocardial infarction/heart failure hospitalization at 1 year.

RESULTS

IMR and LVEDP were both measured in 131 patients (mean age 59±10.7 years, 103 [78.6%] male, 48 [36.6%] with anterior myocardial infarction). The median IMR was 29 (interquartile range, 17-55), the median LVEDP was 17 mm Hg (interquartile range, 12-21), and the correlation between them was not statistically significant (r=0.15; P=0.087). Fifty-three patients (40%) had low IMR (≤32) and low LVEDP (≤18), 18 (14%) had low IMR and high LVEDP, 31 (24%) had high IMR and low LVEDP, while 29 (22%) had high IMR and high LVEDP. Infarct size (% LV mass), LV ejection fraction, final myocardial perfusion grade ≤1, TIMI (Thrombolysis In Myocardial Infarction) flow grade ≤2, and coronary flow reserve were associated with LVEDP/IMR group, as was hospitalization for heart failure (n=18 events; P=0.045) and major adverse cardiac events (n=21 events; P=0.051). LVEDP>18 and IMR>32 combined was associated with major adverse cardiac events, independent of age, estimated glomerular filtration rate, and infarct-related artery (odds ratio, 5.80 [95% CI, 1.60-21.22] P=0.008). The net reclassification improvement for detecting major adverse cardiac events was 50.6% (95% CI, 2.7-98.2; P=0.033) when LVEDP>18 was added to IMR>32.

CONCLUSIONS

IMR and LVEDP in combination have incremental value for risk stratification following primary percutaneous coronary intervention. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02257294.