蒋蔚， M.D.
Duke University Medical Center

 “I have always been impressed by the probability of an important relationship between personality attributes， stress coping strategies and heart disease with myocardial infarction in particular. I have witnessed several friends die suddenly this way. They did not smoke， were not overweight， and their cholesterol levels were unremarkable. But I knew them to be under considerable strain as the result of professional and personal stressors， and I have always believed that their lack of insight， resilience， and emotional resourcefulness， along with their characteristic pattern of responding to stress with helpless anger， significantly contributed to their demise.” ___An anonymous Cardiologist

Clinicians have long recognized the importance of emotional distress on the heart. Now even the lay people may convey not to be too stressed out after being frequently exposed to sceneries that people suffer heart attack when emotionally disturbed. Dr. Wei Jiang， Associate Professor of Medicine and Psychiatry of Duke Health System， a cardiologist originally from China， reviews the findings of researches she and her colleagues conducted over 2-3 decades from field to laboratory， then to the filed.

Holter or Ambulatory monitoring of electrocardiogram out of hospital demonstrated that frequent episodes of ST-segment deviation， an indication of transient myocardial ischemia， occur in the absence of strenuous physical activities， in the presence of emotional arousal， and with onset heart rate well below the level observed during ischemic episode induced by exercise testing. Because of the discover and concern on exercise testing does not necessarily reflect the kinds of challenges people typically encounter during their daily living， a group of physician-scientists in the Western world began to conduct mental stress testing in laboratory setting to understand the underlying pathology in the early 80s.

Although methodologically varied， studies have consistently demonstrated that mental stress testing elicits myocardial ischemia in patients with history of coronary artery disease. Compared to exercise induced myocardial ischemia， mental stress-induced myocardial ischemia (MISMI) rarely manifest in ST-segment deviation， but with more pronounced global ventricular dysfunction (Table) and much smaller double product. Patients rarely report chest pain during MISMI and their diastolic blood pressure are un-proportionally elevated. MSIMI is associated with ischemic activity during daily living and is predictive for poor cardiac outcome over several years following the testing. Such associations are not observed with exercise induced myocardial ischemia in the same sample studied.

Negative emotions， such as frustration， tension， and sadness reported during the mental stress testing are higher among patients who develop MSIMI. Depression， the prevalent psychiatric co-morbidity of cardiac disease and a risk factor for development of ischemic heart disease (IHD) and for poor prognosis of IHD and heart failure， is found to be associated with the likelihood of MSIMI. The greater of depressive symptoms， the more likely patients develop MSIMI in laboratory setting.

It has been demonstrated that mental stress elicits coronary constriction in setting of endothelial injury resulting in restriction of blood supply to myocardium. Mental stress triggers platelet aggregation and itself probably causes endothelial injury.

Therapeutic modalities improve MSIMI is limited. Pharmacologically， there has been single agent proven to be effective， though bate blocker may reduce MSIMI among patients who have high heart rate responses to mental stress. Aerobic exercise training and cognitive behavioral therapy may be helpful but fully engaging patients into those therapies are challenging. Dr. Jiang’s research team is currently investigating whether certain antidepressant medications may improve MSIMI.  

Table. Comparison of Ischemic Manifestation between Mental Stress Testing and Exercise testing
Myocardial Ischemic Activity (N=136)
Ischemic Marker Mental Stress-Induced(%) Exercise-Induced(%)
WMA 43 (34.1) 63 (50)
LVEF reduction >5% 72 (57.1) 45 (35.7)
LVEF reduction or WMA 84 (66.7) 86 (68.3)
ECG ST change 0 44 (35.8)
            WMA = Left ventricular segmental wall motion abnormality
            LVEF = Left ventricular ejection fraction
            ECG = Electrocardiogram