Gregor Fahrni

How does coronary stent implantation impact on the status of the microcirculation during primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction?

Aims Primary percutaneous coronary intervention (PPCI) is the optimal treatment for patients presenting with ST-elevation myocardial infarction (STEMI). An elevated index of microcirculatory resistance (IMR) reflects microvascular function and when measured after PPCI, it can predict an adverse clinical outcome. We measured coronary microvascular function in STEMI patients and compared sequential changes before and after stent implantation. Methods and results In 85 STEMI patients, fractional flow reserve, coronary flow reserve, and IMR were measured using a pressure wire (Certus, St Jude Medical, St Paul, MN, USA) immediately before and after stent implantation. Stenting significantly improved all of the measured parameters of coronary physiology including IMR from 67.7 [interquartile range (IQR): 56.2–95.8] to 36.7 (IQR: 22.7–59.5), P < 0.001. However, after stenting, IMR remained elevated (>40) in 28 (32.9%) patients. In 15 of these patients (17.6% of the cohort), only a partial reduction in IMR occurred and these patients were more likely to be late presenters (pain to wire time >6 h). The extent of jeopardized myocardium [standardized beta: −0.26 (IMR unit/Bypass Angioplasty Revascularization Investigation score unit), P: 0.009] and pre-stenting IMR [standardized beta: −0.34 (IMR unit), P: 0.001] predicted a reduction in IMR after stenting (ΔIMR = post-stenting IMR − pre-stenting IMR), whereas thrombotic burden [standardized beta: 0.24 (IMR unit/thrombus score unit), P: 0.01] and deployed stent volume [standardized beta: 0.26 (IMR unit/mm3 of stent), P: 0.01] were associated with a potentially deleterious increase in IMR. Conclusion Improved perfusion of the myocardium by stent deployment during PPCI is not universal. The causes of impaired microvascular function at the completion of PPCI treatment are heterogeneous, but can reflect a later clinical presentation and/or the location and extent of the thrombotic burden.

CMR Native T1 Mapping Allows Differentiation of Reversible Versus Irreversible Myocardial Damage in ST-Segment-Elevation Myocardial Infarction: An OxAMI Study (Oxford Acute Myocardial Infarction).

Background— CMR T1 mapping is a quantitative imaging technique allowing the assessment of myocardial injury early after ST-segment–elevation myocardial infarction. We sought to investigate the ability of acute native T1 mapping to differentiate reversible and irreversible myocardial injury and its predictive value for left ventricular remodeling. Methods and Results— Sixty ST-segment–elevation myocardial infarction patients underwent acute and 6-month 3T CMR, including cine, T2-weighted (T2W) imaging, native shortened modified look-locker inversion recovery T1 mapping, rest first pass perfusion, and late gadolinium enhancement. T1 cutoff values for oedematous versus necrotic myocardium were identified as 1251 ms and 1400 ms, respectively, with prediction accuracy of 96.7% (95% confidence interval, 82.8% to 99.9%). Using the proposed threshold of 1400 ms, the volume of irreversibly damaged tissue was in good agreement with the 6-month late gadolinium enhancement volume (r=0.99) and correlated strongly with the log area under the curve troponin (r=0.80) and strongly with 6-month ejection fraction (r=−0.73). Acute T1 values were a strong predictor of 6-month wall thickening compared with late gadolinium enhancement. Conclusions— Acute native shortened modified look-locker inversion recovery T1 mapping differentiates reversible and irreversible myocardial injury, and it is a strong predictor of left ventricular remodeling in ST-segment–elevation myocardial infarction. A single CMR acquisition of native T1 mapping could potentially represent a fast, safe, and accurate method for early stratification of acute patients in need of more aggressive treatment. Further confirmatory studies will be needed.

Prognostic Value of “Routine” Cardiac Stress Imaging 5 Years After Percutaneous Coronary Intervention : The Prospective Long-Term Observational BASKET (Basel Stent Kosteneffektivitäts Trial) LATE IMAGING Study

OBJECTIVE This study sought to evaluate the prognostic value of routine stress myocardial perfusion scintigraphy (MPS) 5 years after percutaneous coronary intervention (PCI). BACKGROUND Current appropriate use criteria define routine cardiac stress imaging <2 years after PCI as inappropriate and >2 years as uncertain in asymptomatic patients. METHODS All 339 of 683 BASKET (Basel Stent Kosteneffektivitäts Trial) 5-year survivors (55%) consenting to undergo protocol-mandated MPS and subsequent evaluation irrespective of symptoms were followed for major adverse cardiac events (MACE) (cardiac death, myocardial infarction [MI], or revascularization). For MPS, summed perfusion scores were calculated and perfusion defects were related to treated-vessel or remote myocardial areas. RESULTS Patients were 72 ± 10 years of age, 18% were female, and 90% were free of angina. MPS findings were abnormal in 205 of 339 patients (60%) with complete follow-up. During 3.7 ± 0.3 years, there were 7 cardiac deaths, 18 MIs, and 47 revascularizations, resulting in a MACE rate of 4.4% and a cardiac mortality rate of 0.6% per year. Patients with abnormal MPS findings had higher hazard ratios (HR) for MACE (HR: 1.95; 95% confidence interval [CI]: 1.06 to 3.59; p = 0.032), and cardiac death/MI (HR: 2.50; 95% CI: 0.93 to 6.69; p = 0.066) than patients with normal MPS finding. MACE rates were similar in patients with symptomatic and silent ischemia (p = 0.61) but higher than in patients with normal MPS findings (p < 0.05 for both comparisons). MACE rates were independently predicted by remote ischemia but not by treated-vessel ischemia or scar. CONCLUSIONS Abnormal MPS findings 5 years after PCI are frequent irrespective of symptoms. The predictive power of abnormal MPS lies more in the detection of persistent or progressing coronary artery disease in remote vessel areas than in the diagnosis of late intervention-related problems in treated vessels.

Hyperaemic microvascular resistance predicts clinical outcome and microvascular injury after myocardial infarction

Objectives Early detection of microvascular dysfunction after acute myocardial infarction (AMI) could identify patients at high risk of adverse clinical outcome, who may benefit from adjunctive treatment. Our objective was to compare invasively measured coronary flow reserve (CFR) and hyperaemic microvascular resistance (HMR) for their predictive power of long-term clinical outcome and cardiac magnetic resonance (CMR)-defined microvascular injury (MVI). Methods Simultaneous intracoronary Doppler flow velocity and pressure measurements acquired immediately after revascularisation for AMI from five centres were pooled. Clinical follow-up was completed for 176 patients (mean age 60±10 years; 140(80%) male; ST-elevation myocardial infarction (STEMI) 130(74%) and non-ST-segment elevation myocardial infarction 46(26%)) with median follow-up time of 3.2 years. In 110 patients with STEMI, additional CMR was performed. Results The composite end point of death and hospitalisation for heart failure occurred in 17 patients (10%). Optimal cut-off values to predict the composite end point were 1.5 for CFR and 3.0 mm Hg cm−1•s for HMR. CFR <1.5 was predictive for the composite end point (HR 3.5;95% CI 1.1 to 10.8), but not for its individual components. HMR ≥3.0 mm Hg cm−1 s was predictive for the composite end point (HR 7.0;95% CI 1.5 to 33.7) as well as both individual components. HMR had significantly greater area under the receiver operating characteristic curve for MVI than CFR. HMR remained an independent predictor of adverse clinical outcome and MVI, whereas CFR did not. Conclusions HMR measured immediately following percutaneous coronary intervention for AMI with a cut-off value of 3.0 mm Hg cm−1 s, identifies patients with MVI who are at high risk of adverse clinical outcome. For this purpose, HMR is superior to CFR.

Index of Microcirculatory Resistance at the Time of Primary Percutaneous Coronary Intervention Predicts Early Cardiac Complications: Insights From the OxAMI (Oxford Study in Acute Myocardial Infarction) Cohort

Background Early risk stratification after primary percutaneous coronary intervention (PPCI) for ST‐segment–elevation myocardial infarction is currently challenging. Identification of a low‐risk group may improve triage of patients to alternative clinical pathways and support early hospital discharge. Our aim was to assess whether the index of microcirculatory resistance (IMR) at the time of PPCI can identify patients at low risk of early major cardiac complications and to compare its performance against guideline‐recommended risk scores. Methods and Results IMR was measured using a pressure–temperature sensor wire. Cardiac complications were defined as the composite of cardiac death, cardiogenic shock, pulmonary edema, malignant arrhythmias, cardiac rupture, and presence of left ventricular thrombus either before hospital discharge or within 30‐day follow‐up. In total, 261 patients undergoing PPCI who were eligible for coronary physiology assessment were prospectively enrolled. Twenty‐two major cardiac complications were reported. Receiver operating characteristic curve analysis confirmed the utility of IMR in predicting complications and showed significantly better performance than coronary flow reserve, the Primary Angioplasty in Myocardial Infarction II (PAMI‐II), and Zwolle score (P≤0.006). Low microvascular resistance (IMR ≤40) was measured in 159 patients (61%) of the study population and identified all patients who were free of major cardiac complications (sensitivity: 100%; 95% CI, 80.5–100%). Conclusions IMR immediately at the end of PPCI for ST‐segment–elevation myocardial infarction reliably predicts early major cardiac complications and performed significantly better than recommended risk scores. These novel data have implications for early risk stratification after PPCI.

Switzerland: coronary and structural heart interventions from 2010 to 2015

In 2015, Switzerland had a population of 8.3 million inhabitants. Since the first coronary angioplasty performed by Andreas Grüntzig in Zurich in 1977, the number of percutaneous procedures has steadily increased. The aim of this report is to summarise the current state of catheter-based cardiac interventions in adults in the country and to detail trends between 2010 and 2015. Since 1987, the Working Group for Interventional Cardiology of the Swiss Society of Cardiology has collected annually aggregate data from all facilities with cardiac catheterisation laboratories in the country. In 2015, a total of 37 institutions covered 17 of the 26 Swiss cantons. Over the six-year period, there was a continuous increase in the number of coronary angiography and percutaneous coronary interventions (PCI) (median increase rate of 3.2%/year for coronary angiography and of 2.6%/year for PCI). Notable was the adoption of the transradial approach for PCI, going from a median rate of 17% in 2012 to 51.9% in 2015. With respect to structural heart interventions, the number of patent foramen ovale as well as atrial septal defect closures has remained stable, while the number of transcatheter aortic valve implantations and transcatheter mitral valve repairs has shown a fourfold increase.

Improved Coronary Sinus Blood Sampling for Cardiac Research

Background: Coronary sinus (CS) blood sampling is important for measuring metabolites and biomarkers in cardiovascular research, but can be technically challenging. Here we demonstrate the use of the antecubital fossa for CS blood sampling as an alternative to femoral access, and a simple technique of paired venous and CS blood gas analysis for confirmation of valid CS sampling. We also demonstrate improvement in sampling accuracy by using a coronary guide wire to stabilize the sampling catheter in the CS. Methods: Paired blood samples from CS and peripheral vein were collected from patients at the time of primary PCI for acute myocardial infarction. Venous access for CS sampling was via the antecubital vein. Blood gas analysis was used to confirm a true CS sample (pO2[CS]<pO2[v]). CS sampling was carried out with a catheter in the CS (standard technique) or with the addition of a coronary guide wire for stability (modified technique). Results: 108 patients underwent CS and peripheral venous blood sampling. The standard technique for CS sampling was used in 62 patients and the modified technique in 46 patients. Blood gas analysis confirmed a true CS sample in 77% of patients using the standard technique and 100% using the modified technique. Conclusions: CS blood sampling via the antecubital fossa is feasible and safe. Blood gas analysis of paired venous and CS samples can be used to confirm a valid CS sample. A coronary guide wire can be used to stabilise the sampling catheter in the CS, and this increases CS sampling accuracy.

Supra-annular sizing for transcatheter valve implantation in bicuspid aortic stenosis

Introduction Transcatheter aortic valve implantation (TAVI) is an established treatment option for symptomatic severe aortic stenosis in high [1] and intermediate risk patients [2]. With a prevalence of 1% to 2% in countries outside China, bicuspid aortic valve (BAV) disease is a common congenital malformation [3] that often results in premature aortic stenosis. Since BAV represents a challenge for interventional treatment [4], it traditionally has been considered as a relative contraindication against TAVI. The Lotus valve (Boston Scientific Corp, Marlborough MA) is a mechanically expandable, fully repositionable and retrievable second-generation TAVI prosthesis with an outer adaptive seal that facilitates accurate positioning, early valve function, and hemodynamic stability during deployment, and minimizes paravalvular leakage [5]. Therefore, it might be a good treatment option for BAV stenosis. For planning TAVI procedures, an in-depth analysis of multidetector computed tomography (MDCT) images is crucial. In most reports of interventional treatment of BAV stenosis, preprocedural measurements were done according to current guidelines [6]. However, such measurements might lead to inaccurate annular sizing and prosthesis selection in BAV disease. Specifically, measurement of the basal ring may lead to the selection of too large prostheses, potentially leading to suboptimal results, or may make the intervention impossible due to non-availability of the necessary large valve sizes.

PREDICTING THE OUTCOME OF REPERFUSION ACUTELY IN PATIENTS WITH STEMI - DERIVATION AND VALIDATION OF THE ATI SCORE

Aim Restoration of effective myocardial reperfusion by primary percutaneous coronary intervention (PPCI) in patients with STEMI is not predictable. A method to assess the likelihood of a suboptimal response to conventional pharmaco-mechanical therapies could be beneficial. We aimed to derive and validate a scoring system that can be used acutely at the time of coronary reopening to predict the likelihood of downstream microvascular impairment in patients with STEMI. Methods and Results A score estimating the risk of post-procedural microvascular injury defined by an index of microcirculatory resistance (IMR) > 40, was initially derived in a cohort of 85 STEMI patients (Derivation cohort). This score was then tested and validated in three further cohorts of patients (Retrospective (30 patients), Prospective (42 patients) and External (29 patients). The ATI score [Age ( > 50 = 1); pre-stenting IMR (> 40 and < 100 = 1; ≥ 100 = 2); Thrombus score (4=1; 5=3)] was highly predictive of a post-stenting IMR > 40 in all the four cohorts (AUC:0.87; p < 0.001-Derivation cohort, 0.84; p: 0.002-Retrospective cohort, 0.92; p < 0.001-Prospective cohort and 0.81; p: 0.006-External cohort). In the whole population an ATI score ≥ 4 presented a 95.1% risk of final IMR >40, while no cases of final IMR >40 occurred in the presence of an ATI score < 2. Conclusions The ATI score appears to be a promising tool capable of identifying patients during PPCI that are at the highest risk of an adverse outcome following revascularisation.