What Killed Michael Jackson?

The news says it was a heart attack.  I'm not so sure.  There are so many variables here, it's hard to know where to begin.  First of all, in medical jargon, physicians often think of a heart attack as a myocardial infarction, a condition where a sudden occlusion of a major arterial vessel to the heart results in a loss of oxygen to valuable heart muscle.  There is a whole spectrum of ischemic disease.  It can start with stable angina, a relatively benign condition that can be managed for years with appropriate medications and elective procedures.  More concerning is unstable angina, or chest pain or its anginal equivalent that generally occurs at rest.  Most physicians would consider unstable angina a reason for admission and close hospital monitoring.  

Progressing farther along the cardiac spectrum, non ST elevation MI occurs when lack of oxygen to the heart results in damage to heart muscle that results in leakage of cardiac specific enzymes into the blood stream.  It is this cardiac marker, the troponin, that physicians use to measure the presence or absence of cardiac muscle death.  The lack of ST segment elevation generally means that the damage is not transmural.  In other words, the full thickness of the heart is not being compromised.  This can is also generally managed in the hospital as a non life threatening condition.  And depending on the clinical scenario treatment can include medications, PCI, surgery or a combination of the three.

The ST segment elevation MI is the emergency that kills.  How quickly you intervene has everything to do with life or death.  ST segment is an ECG finding that indicates  trans mural, or complete thickness death of the cardiac muscle.  With out specialized interventions, either tPA or PCI, the patient will have a high probability of severe morbidity or death.

So, did Michael Jackson have a "heart attack", classically understood by physicians as a myocardial infarction (MI)?  I don't know.  The most important risk factors for acute MI are:

• diabetes
• hypertension
• hyperlipidemia
• smoking
• central obesity/inactivity
• family history
• history of vascular disease in other sources

Other less common but still relevant causes include

• systemic inflammatory disease such as autoimmune conditions (lupus, rheumatoid arthritis)
• illicit drugs (meth, cocaine)
• coagulopathy (perhaps antiphospholipid antibody syndrome)
• radiation exposure
• untreated hyper or hypothyroidism
• prinzmetal's angina

There are many others but these are most common.

Mr Jackson, on the surface doesn't appear to have major risk factors for premature coronary artery disease that could lead to an early MI.  I've never seen him smoke.  His family all appears free of heart disease.  He is physically active.  He probably does not have diabetes, nor hypertension.  His cholesterol status is unknown.  He very well may have an autoimmune disorder as he has claimed to have many ailments over the years.  However, having systemic lupus would make it quite difficult for him to lead an active lifestyle as he has.

While possible, I'm not convinced it was an MI per say that killed him.  I think the more likely cause may have been sudden cardiac death, not by infarction  of one or more blood vessels , but rather by a global hypoxemia caused by a deadly arrhythmia, most notably ventricular tachycardia or ventricular fibrillation.  Now, either rhythm can be initiated by a myocardial infarction, or they can be a primary source of death.

Someone with intrinsic coronary artery disease is more likely to have VT or VF than someone without, but VT and VF can occur in those with out active ischemia or infarction.  QT prolongation or other genetic arrythmogenic conditions could have caused his demise.  Hypertrophic obstructive cardiomyopathy could have as well.    Street drugs, herbs,  supplements and prescription drugs could all initiate a deadly arrhythmia.  

The autopsy will be helpful to determine the extent of coronary artery disease, if any.  If he appears clear of underlying chronic disease, one would have to start looking towards more acute causes.   Drug overdose. Primary respiratory failure.  Pulmonary embolism (he does travel quite a bit).  The information on the field will be helpful ( in terms of what the cardiac rhythms were), what he was doing when he collapsed, any discussion with folks around him right before he collapsed.  It can all be pieced together to get a final cause as the most likely cause of death.

Because, as all physicians know, cardiopulmonary arrest is not an appropriate cause of death.