Cardiac Syndrome X and Microvascular Angina

Role of inflammation and endothelial dysfunction in the pathogenesis of cardiac syndrome X

Chest pain with normal coronary arteriograms represents a major diagnostic and therapeutic challenge to contemporary cardiology. Cardiac syndrome X (CSX), defined as typical angina-like chest pain, a positive response to exercise stress testing and normal coronary arteriograms, encompasses patients with a variety of pathogenic mechanisms. Cardiac ischemia has been documented in approximately 25% of CSX patients and is associated with endothelial dysfunction and microvascular vasodilator abnormalities. Increased endothelin-1, a powerful vasoconstrictor, has been suggested to play a pathogenic role. There is a high prevalence of postmenopausal women with CSX and thus estrogen deficiency has also been proposed to represent a possible pathogenic mechanism. Inflammatory mechanisms and endothelial dysfunction at the coronary microvascular level appear to be important in the pathogenesis of CSX. Treatment with agents that have protective effects on the vasculature and also anti-inflammatory properties, such as statins and angiotensin-converting enzyme inhibitors have been effective in improving both symptoms and electrocardiographic signs of myocardial ischemia in patients with CSX. This review discusses the roles for endothelial dysfunction and inflammation in the pathogenesis of CSX, as well as the potential therapeutic implications of these mechanisms.

Noncardiac chest pain: diagnostic evaluation

Noncardiac chest pain (NCCP) is a common and challenging clinical problem. It is estimated that more than 70 million Americans (23% of the population) suffer from this condition yearly. Patients with NCCP represent a diagnostic dilemma. Their chest pain is often indistinguishable from cardiac pain leading to extensive and expensive evaluations. Once coronary artery disease and other cardiac and pulmonary sources of chest pain are excluded, patients are frequently referred to gastroenterologists to look primarily for esophageal sources of pain. A variety of diagnostic tests are available to the practicing clinician to identify the origin of pain, including ambulatory pH testing, esophageal motility, upper endoscopy, provocative testing and even therapeutic trials.

Exercise-induced intra-ventricular gradients as a frequent potential cause of myocardial ischemia in cardiac syndrome X patients

Background

The development of intra-ventricular gradients (IVG) during dobutamine or exercise stress is not infrequent, and can be associated to symptoms during stress.

The purpose of this study was to assess the occurrence of IVG during exercise stress echocardiography in cardiac syndrome X patients.

Methods

We prospectively evaluated 91 patients (pts) mean aged 51 ± 12 years (age ranged 20 to 75 years old), 44 of whom were women. All pts had angina, positive exercise ECG treadmill testing, normal rest echocardiogram and no coronary artery disease on coronary angiogram (cardiac X syndrome). After complete Doppler echocardiographic evaluation with determination of left ventricular outflow tract index (LVOTi), relative left ventricular wall thickness (RLVWT) and left ventricular end-diastolic volume index (LVDVi), all patients underwent stress echocardiography with two-dimensional and Doppler echographic evaluation during and after treadmill exercise.

Results

For analysis purpose patients were divided in 2 groups, according to the development of IVG. Doppler evidence of IVG was found in 33 (36%) of the patients (Group A), with mean age 47 ± 14 years old (age ranged 20 to 72 years) and with a mean end-systolic peak gradient of 86 ± 34 mmHg (ranging from 30 to 165 mmHg). The IVG development was accompanied by SAM of the mitral valve in 23 pts. Three of these pts experienced symptomatic hypotension. Ten were women (30% pts). 58 pts in group B, 34 of whom were women (59%) (p = 0,01 vs group A), mean aged 53,5 ± 10,9 years old (age ranged 34 to 75 years) (p = 0,03 vs group A), did not develop IVG. LVOTi was 10,29 ± 0,9 mm/m² in group A and 11,4 ± 1 mm/m² in group B (p < 0,000); RLVWT was 0,36 ± 0,068 in group A and 0,33 ± 0,046 in group B (p < 0,01); LVDVi was 44,8 ± 10 ml/m² in group A and 56 ± 11,6 ml/m² in group B (p = 0,000).

Conclusion

1. A significant number of patients with cardiac X syndrome developed IVG during upright exercise in treadmill. These pts (group A) are mainly males and younger than those who did not develop IVG.

2. The development of IVG and mitral valve SAM on exertion seems to be associated with ST segment downsloping during stress testing in patients without epicardial coronary disease.

3. The development of IVG and mitral valve SAM seems to be associated with lower LVOTi, lower LVDVi and higher RLVWT.

The pathophysiology of non-cardiac chest pain

Various underlying mechanisms have been described in patients with non-cardiac chest pain (NCCP). By far, gastroesophageal reflux disease (GERD) is the most common cause and thus requires initial attention when patients with NCCP are managed. Esophageal dysmotility can be demonstrated in 30% of the NCCP patients, but appears to play a very limited role in symptom generation. A significant number of patients with NCCP lack any evidence of GERD and have been consistently shown to have reduced perception thresholds for pain. Peripheral and/or central sensitization have been suggested to be responsible for visceral hypersensivity in NCCP patients. Further understanding of the underlying mechanisms for pain in patients with NCCP will likely improve our current therapeutic approach.