Definitions and Epidemiology of Coronary Functional Abnormalities

Coronary functional abnormalities are frequent causes of angina pectoris, particularly in patients with unobstructed coronary arteries. There is a spectrum of endotypes of functional coronary abnormalities with different mechanisms of pathology including enhanced vasoconstriction (i.e. coronary artery spasm) or impaired vasodilatation, such as impaired coronary flow reserve or increased microvascular resistance. These vasomotor abnormalities can affect various compartments of the coronary circulation such as the epicardial conduit arteries and/or the coronary microcirculation. Unequivocal categorisation and nomenclature of the broad spectrum of disease endotypes is crucial both in clinical practice as well as in clinical trials. This article describes the definitions of coronary functional abnormalities with currently accepted cut-off values, as well as diagnostic methods to identify and distinguish endotypes. The authors also provide a summary of contemporary data on the prevalence of the different endotypes of coronary functional abnormalities and their coexistence

Coronary Artery Spasm: The Interplay Between Endothelial Dysfunction and Vascular Smooth Muscle Cell Hyperreactivity

Patients with angina pectoris, the cardinal symptom of myocardial ischaemia, yet without significant flow-limiting epicardial artery stenosis represent a diagnostic and therapeutic challenge. Coronary artery spasm (CAS) is an established cause for anginal chest pain in patients with angiographically unobstructed coronary arteries. CAS may occur at the epicardial level and/or in the microvasculature. Although the underlying pathophysiological mechanisms of CAS are still largely unclear, endothelial dysfunction and vascular smooth muscle cell (VSMC) hyperreactivity seem to be involved as major players, although their contribution to induce CAS is still seen as controversial. This article will look at the role and possible mechanistic interplay between an impaired endothelial and VSMC function in the pathogenesis of CAS

Does Coronary Microvascular Spasm Exist? Objective Evidence from Intracoronary Doppler Flow Measurements During Acetylcholine Testing

A 43-year-old woman with recurrent atypical angina underwent invasive coronary angiography including intracoronary Doppler blood flow assessment and coronary spasm provocation testing. While obstructive epicardial disease could be ruled-out angiographically, the patient experienced reproduction of her angina symptoms after intracoronary administration of acetylcholine (100 µg) during spasm provocation testing. Simultaneously, the ECG showed new-onset ST-segment depression in the absence of epicardial spasm. In addition, coronary flow velocity was significantly reduced after acetylcholine compared to the baseline condition. Following intracoronary administration of nitroglycerine (200 µg), the patient’s symptoms as well as the ECG changes and coronary flow reduction were reversed. Considering the ongoing challenges in appropriate evaluation of the pathophysiological mechanisms of coronary microvascular dysfunction, simultaneous intracoronary Doppler flow measurement during spasm testing – as shown in this case – may provide objective evidence for microvascular spasm in addition to the standardized diagnostic criteria, especially if they are ambiguous

Adjuvant Use of Ivabradine in Acute Heart Failure due to Myocarditis

We report two cases of young men in whom acute heart failure due to myocarditis was diagnosed. The patients had been transferred to the intensive care unit (ICU) with commencing symptoms of acute heart failure and consecutive multiorgan failure for further treatment and to evaluate the indication for implantation of a ventricular assist device or for high urgent orthotopic heart transplantation. In both patients, the If-channel inhibitor ivabradine was administered off-label to provide selective heart rate reduction, and thus support hemodynamic stabilization. Though currently considered off-label use in patients suffering from severe hypotension and acute heart failure, the use of ivabradine may beneficially influence outcome by allowing optimization of the patient's heart rate concomitant to initial measures of clinical stabilization

Conditional HIF-1α Expression Produces a Reversible Cardiomyopathy

The response to hypoxia in tissues is regulated by the heterodimeric transcription factor Hypoxia Inducible Factor-1 (HIF-1).We have created a strain of mice with inducible cardiomyocyte-specific expression of a mutated, oxygen-stable, form of HIF-1alpha. Cardiac function steadily decreased with transgene expression, but recovered after the transgene was turned off. Using long-oligo microarrays, we identified 162 transcripts more than 3-fold dysregulated in these hearts after transgene expression. Among the down-regulated genes the transcript for SERCA was reduced 46% and the protein 92%. This led us to an evaluation of calcium flux that showed diminished reuptake of cytoplasmic calcium in myocytes from these hearts, suggesting a mechanism for cardiac dysfunction.These results provide a deeper understanding of transcriptional activity of HIF in the heart, and show that enhanced HIF-1 activity is sufficient to cause contractile dysfunction in the adult heart. HIF is stabilized in the myocardium of patients with ischemic cardiomyopathy, and our results suggest that HIF could be contributing directly to the contractile dysfunction in this disease

Invasive Diagnosis of Coronary Functional Disorders Causing Angina Pectoris

Coronary vasomotion disorders represent a frequent cause of angina and/or dyspnoea in patients with non-obstructed coronary arteries. The highly sophisticated interplay of vasodilatation and vasoconstriction can be assessed in an interventional diagnostic procedure. Established parameters characterising adequate vasodilatation are coronary blood flow at rest, and, after drug-induced vasodilation, coronary flow reserve, and microvascular resistance (hyperaemic microvascular resistance, index of microcirculatory resistance). An increased vasoconstrictive potential is diagnosed by provocation testing with acetylcholine or ergonovine. This enables a diagnosis of coronary epicardial and/or microvascular spasm. Ischaemia associated with microvascular spasm can be confirmed by ischaemic ECG changes and the measurement of lactate concentrations in the coronary sinus. Although interventional diagnostic procedures are helpful for determining the mechanism of the angina, which may be the key to successful medical treatment, they are still neither widely accepted nor applied in many medical centres. This article summarises currently well-established invasive methods for the diagnosis of coronary functional disorders causing angina pectoris