Marcos García-Guimaraes

Spontaneous coronary artery dissection: new insights into diagnosis and treatment.

Spontaneous coronary artery dissection (SCAD) remains an infrequent, elusive, and challenging clinical entity of unknown etiology eight decades after its initial description. Our understanding of the pathophysiology of SCAD, initially limited to information from early pathological studies, case reports, and very short series, has been enriched recently by relatively large contemporary series of patients studied prospectively. The typical presentation involves a young woman without coronary risk factors suffering an acute coronary syndrome but, actually, most patients are middle-aged and have coronary risk factors. A high number of conditions have been related to SCAD, but fibromuscular dysplasia has shown a major intriguing association with potential pathophysiological implications. SCAD may present (a) with an intimal tear and the classic angiographic ‘flap’ leading to the appearance of two lumens (true and false), or (b) without an intimal rupture, as an intramural hematoma. An increased clinical awareness together with new diagnostic tools have led to a major surge in the diagnosis of SCAD. High-resolution intracoronary techniques provide unique diagnostic insights into the underlying pathophysiology and facilitate identification of the disease in patients misdiagnosed previously. After the initial acute ischemic insult, most patients stabilize and have a benign clinical course and eventually experience spontaneous healing of the vessel wall during follow-up. However, recurrences may still occur in up to 10–20% of cases. Accordingly, a conservative medical management (watchful waiting strategy) has been recommended as the initial approach. Revascularization remains particularly challenging and may be associated with suboptimal results, acute complications, and poor long-term outcome. Nevertheless, in patients with ongoing or refractory ischemia and adequate anatomy, revascularization should be attempted. Some novel and attractive coronary interventions have been proposed in this uniquely challenging anatomic scenario. This review aims to present a comprehensive and contemporary update on this elusive and intriguing clinical entity.

Optical Coherence Tomography Findings in Patients With Stent Thrombosis

INTRODUCTION AND OBJECTIVES Stent thrombosis (ST) is a rare but potentially serious complication. Optical coherence tomography (OCT) provides high-resolution images and additional information to angiography in the study of this event. METHODS Prospective study of patients with ST undergoing reintervention with OCT imaging. RESULTS The study included a total of 40 consecutive patients with ST. Mean age was 69 ± 13 years and 83% were male. Early ST (≤ 30 days) was observed in 16 patients and late ST (> 30 days) in 24 patients. Stent thrombosis occurred in 17 bare-metal stents and 23 drug-eluting stents. In 34 patients (85%), adequate OCT images were obtained at the time of the ST. The predominant mechanism in early ST was stent malapposition (39%). In late ST, high frequencies of uncovered (46%) and malapposed struts (17%) were observed, especially in patients with drug-eluting stents. Furthermore, the presence of neoatherosclerosis was very high (67%) in patients with late ST. After intervention, improvements were observed in malapposition length and the amount of residual thrombus. CONCLUSIONS OCT allows identification of the underlying mechanisms potentially involved in ST. This imaging modality is helpful in guiding reintervention in these patients, which improves the area and length of malapposition, as well as the maximal residual thrombus area.

Time-Related Microcirculatory Dysfunction in Patients With Takotsubo Cardiomyopathy

This study assesses whether there is a time-dependent trend in microvascular damage in patients presenting with takotsubo cardiomyopathy by invasively measuring the index of microvascular resistance.

Restenosis of Coronary Bioresorbable Vascular Scaffolds

Bioresorbable vascular scaffold (BVS) devices have represented an authentic conceptual revolution in interventional cardiology. Their particular design ensures perfect scaffolding for the vascular wall and has led to excellent immediate outcomes. Furthermore, they incorporate a drug with potent antiproliferative properties, which averts the development of restenosis. These 2 properties are also inherent to drug-eluting stents (DES) made of metal. Nonetheless, the attractiveness of BVS is that once their function has been achieved (vascular support and antiproliferative effect), both the scaffold and the polymer used to administer the drug completely disappear from the coronary wall. In contrast, with DES a metallic structure always remains in the vascular wall, and in those not containing a bioresorbable polymer, the permanent polymer covering the stent also persists. Several studies have conclusively confirmed that BVS completely disappear from the vascular wall over time, usually within a period of around 3 years. This implies that the artery will be released from the corset-like effect of a metallic mesh structure in its interior and can recover its physiologic functions. The vessel can respond once again to the stimuli generated by the coronary flow (sheer stress), which may favor chronic phenomena of adaptive vascular remodeling and late lumen gain. Recovery of the physiologic vascular dynamics is also achieved, with restoration of acute vasodilation or vasoconstriction responses to various stimuli and drugs. Some data have even indicated that regression of the underlying atheromatous plaque can occur in the treated region, and that implantation of BVS over vulnerable or complicated plaques may help to stabilize them. Resorption also frees lateral branch vessels that have been ‘‘caged’’ by the scaffold. Moreover, the eventual disappearance of BVS structural elements that were improperly placed against the vessel wall (malapposition) due to an inadequate technique or unfavorable anatomy, and those that protrude excessively (in ostial lesions) may avoid the development of late complications. Finally, the nonmetallic structure of these scaffolds (with a platinum marker at each end) enables proper evaluation of the coronary anatomy by noninvasive techniques (eg, coronary computed tomography) because it does not produce radiologic artifacts, as occurs with metallic stents. There is some evidence that the permanent presence of foreign elements in the vessel wall may promote the development of adverse events during follow-up. Very late thrombosis causes the greatest concern, but late restenosis has also been described, sometimes caused by neoatherosclerosis. BVS were designed in an attempt to circumvent all these limitations, associated with DES. Numerous studies have reported excellent clinical results following BVS implantation. Observational studies and randomized studies performed in selected patients have both reported outcomes similar to those achieved with latest-generation DES. If the 1-year results obtained with these scaffolds are similar to those of the newest DES, it is tempting to speculate that the very long-term outcome may also be favorable for BVS-treated patients. We should remember, however, that the currently available scaffolds contain relatively thick support elements (156 mm) to ensure sufficient radial strength; therefore, they are inferior to the new generations of DES in terms of flexibility and navigability. This explains why their use has been constrained and cautious in patients with complex or calcified lesions. Furthermore, shaping and adaptation of current BVS to the vessel is very limited because of their plastic composition. Therefore, the diameters of these devices must be carefully chosen, as excessive expansion (or dilatation of the cells in the case of lateral branches) can cause fracture and disruption of the support elements. These problems rarely occur with DES, which allow for greater adaptation while maintaining their structural integrity within the limits required in clinical practice. These factors explain why the favorable initial results obtained with BVS (similar to those of the newest DES) are applicable to relatively straightforward lesions. As has always occurred in the history of interventional cardiology, every innovation is understandably accompanied by an initial phase of enthusiasm, which at some point becomes subdued by data that generate concern and reflection within the scientific community. One only has to recall the provocative editorial published not long ago in this same journal, predicting that we had achieved every interventional cardiologist’s dream: a 0% restenosis rate! However, reality soon returned us to a more cautious and humble scenario. Usually, the next phase of an innovation entails incorporation of additional technological advances, and the new devices are better used. The initial limitations are overcome and the innovation becomes consolidated, which Rev Esp Cardiol. 2017;70(7):527–531

Drug-eluting balloons in coronary interventions: the quiet revolution?

ABSTRACT Introduction: Drug-eluting balloons (DEB) may be considered as a ‘quiet revolution’ in percutaneous coronary interventions. Early-generation DEB eluting paclitaxel proved to be very effective in animal models to reduce neointimal hyperplasia. Areas covered: Review of DEB efficacy in patients with coronary de novo lesions and in-stent restenosis (ISR). Expert opinion: Many randomized clinical trials and meta-analyses have demonstrated the value of DEB in patients with ISR. In this setting, DEB are safe and effective with clinical and angiographic results superior to plain balloon angioplasty and at least equivalent to first generation drug-eluting stents (DES). In selected ‘de novo’ lesions (bifurcation lesions, small vessels, diffuse disease, myocardial infarction) DEB represent an attractive alternative although additional evidence in these ‘niche’ indications is still required before a widespread clinical utilization can be recommended. Recently, new generation DEB have become available, offering interesting new possibilities (paclitaxel and also sirolimus) for coronary interventions. Further studies are required to compare the results of novel generation DEB with those of second-generation DES.

Diagnostic accuracy of a hybrid approach of instantaneous wave-free ratio and fractional flow reserve using high-dose intracoronary adenosine to characterize intermediate coronary lesions: Results of the PALS (Practical Assessment of Lesion Severity) prospective study

We sought to investigate the diagnostic accuracy of instantaneous wave‐free ratio (iFR) and high‐dose intracoronary adenosine fractional flow reserve (IC‐FFR) compared with classical intravenous adenosine fractional flow reserve (IV‐FFR) to assess coronary stenosis severity. The usefulness of two hybrid strategies combining iFR and high‐dose IC‐FFR was also evaluated. Background: Physiological assessment of intermediate coronary stenoses to guide revascularization is currently recommended. Methods: Consecutive real‐world patients with angiographically intermediate coronary stenosis (40–80% diameter stenosis) were prospectively included in the PALS (Practical Assessment of Lesion Severity) study. In every target lesion iFR, high‐dose IC‐FFR and IV‐FFR were systematically measured to assess the accuracy of an hybrid sequential approach combining iFR and IC‐FFR. Results: A total of 106 patients with 121 intermediate coronary lesions were analyzed. Both, iFR and IC‐FFR showed a significant correlation with IV‐FFR (iFR: r = 0.60, 95%CI 0.48–0.70; IC‐FFR: r = 0.88; 95%CI: 0.83–0.92). High‐dose IC‐FFR provided lower FFR values than IV‐FFR (0.81 ± 0.08 vs. 0.82 ± 0.09, P = 0.25). Using a receiver‐operating‐characteristic curve an optimal iFR threshold of 0.91 for the screening test was identified. A sequential test strategy (initial iFR followed by IC‐FFR only in lesions with iFR <0.91) yielded an excellent diagnostic accuracy (96.7%, 95%CI 96.7–99.1%) with a sensitivity, specificity, positive and negative predicted values of 100%, 94.7%, 91.8%, and 100%, respectively. A hybrid approach using the previously described iFR gray zone (0.85–0.94) also provided an excellent diagnostic accuracy (95%, 95%CI: 89.5–98.1%). Conclusions: In patients with intermediate coronary lesions a hybrid strategy by using a sequential approach of iFR and high‐dose IC‐FFR, provided a very good diagnostic performance to identify physiologically significant stenoses.

Bioresorbable vascular scaffolds in patients with acute myocardial infarction: a new step forward to optimized reperfusion?

Bioresorbable vascular scaffolds (BVS) represent a disruptive technology that has caused a new revolution in interventional cardiology. BVS appear to be particularly appealing in patients presenting with an acute myocardial infarction (MI). The available evidence on the value of BVS implantation in this challenging scenario is very promising but still limited. Results come from preliminary small observational studies, prospective registries that include a control group, and from scarce randomized clinical trials with surrogate mechanistic or angiographic primary end-points. Further studies, powered for clinical endpoints, are required to establish the relative safety and efficacy of BVS vs. new-generation metallic drug-eluting stents (DES) in patients with ST-segment elevation acute MI.

Optimal Coronary Interventions in Small Vessels: Is Size All That Matters?

Coronary interventions on small vessels, representing up to 30% to 40% of procedures, are challenging and often disappointing because of suboptimal acute results and high restenosis rates [(1,2)][1]. In this setting, bare-metal stents (BMS) proved to be superior to balloon angioplasty (BA), with the

Current management of spontaneous coronary artery dissection

ABSTRACT Introduction: Spontaneous coronary artery dissection (SCAD) remains an infrequent and elusive clinical entity of unknown etiology. However, our knowledge of SCAD has been significantly enriched in recent years. Large and prospective contemporary series have increased the interest in this disease with fewer patients misdiagnosed and a growing number of cases recognized in daily clinical practice. Classically, SCAD was thought to present mainly in young women without traditional atherosclerotic risk factors but, actually, most patients are middle-aged and are not free from coronary risk factors. A high number of associated conditions have been reported. Of these, fibromuscular dysplasia emerges as a major association with intriguing pathophysiological implications. Areas covered: This review aims to present a contemporary update on SCAD. We concentrate on the clinical scenario, related conditions, practical management and treatment strategies. Expert commentary: Recognition of SCAD is currently much more frequent and accurate as a result of increased clinical awareness and the widespread use of intravascular imaging techniques. Hopefully, in the near future an improvement in the management of SCAD patients will come not only from empirical evidence but also from dedicated clinical trials.

Reliability of physiological assessment of coronary stenosis severity using intracoronary pressure techniques: a comprehensive analysis from a large cohort of consecutive intermediate coronary lesions

AIMS We sought to assess the reliability of the most frequently used intracoronary physiologic indices (including intravenous adenosine FFR [IV-FFR], intracoronary low-dose adenosine FFR [LD-IC-FFR], intracoronary high-dose adenosine FFR [HD-IC-FFR], Pd/Pa and iFR). We also sought to analyse factors affecting their reproducibility in a real-world patient population. METHODS AND RESULTS A total of 91 lesions in 86 consecutive patients were included. Measurements of all physiological indices were repeated within a systematic standardised prospective protocol. All measured indices showed excellent test-retest reliability, with intraclass correlation coefficient (ICC) over 0.96. IV-FFR showed the highest coefficient of variation (CV) values among the studied measurements (Pd/Pa: 0.05; iFR: 0.10; LD-IC-FFR: 0.10; HD-IC-FFR: 0.08; IV-FFR: 0.12). Pd/Pa was significantly less variable than the other indices. On multivariate analysis, female gender, distal lesion location, history of hypertension or kidney failure, as well as presentation as an acute coronary syndrome, were associated with more variability in all physiological intracoronary measurements. CONCLUSIONS The reliability of most frequently used intracoronary physiologic indices is high. Clinical and anatomic factors significantly influence the reliability of these physiologic indices.