Apr 23, 2021
In this podcast, Dr. Scott Sharkey, senior consulting cardiologist with Minneapolis Heart Institute, provides a discussion on cardiomyopathy and more specifically Takotsubo syndrome.
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Cardiomyopathy. According to Dr. Sharkey, it is a general term for cardiac muscle disease, often times of unknown cause. Usually it refers to a dilated, poorly, contracting heart. Though it's also been called stress cardiomyopathy, Takotsubo does not behave like most cardiomyopathies. It's a microcirculatory disease, causing a stunned myocardium similar to an acute myocardial infarction, but with non-obstructive epicardial coronary arteries.
Dr. Sharkey and his colleagues first noticed this phenomenon in patients with myocardial infarction that showed deep T wave inversions on EKG, and initial ECHOs with ejection fractions of 25-30%. Weeks later, these injuries would resolve, findings they attributed to a stunned myocardium.
This phenomenon was then seen in a patient with a TBI, who again had a deep T wave inversion, and a large left ventricular regional wall motion abnormality with normal coronary arteries. The regional wall motion abnormality, again, resolved. These findings were noted in 20 similar cases that were then published in 1998. Though to note, this same syndrome was also present in the Japanese literature at this time.
Later, it was noted patients were developing these symptoms not just from severe illness or trauma, but also from deeply emotional situations. This led to a write-up in Circulation in 2005, which received the 'Paper of the Year' award.
From the early days to now, Dr. Sharkey went from seeing three to four patients per year with Takotsubo, to present day, one to two patients per week. The Minneapolis Heart Institute Foundation has done, and continues to do robust research on Takotsubo, noting that there is a subset of vulnerable patients that actually have recurrences of Takotsubo., They have also been able to study specific triggers for Takotsubo, like drug use, pheochromocytoma and critical illness in general.
Triggers for Takotsubo. As mentioned before, drug use, pheochromocytoma or critical illness are causes, but really any physical illness as well as any emotional stress are triggers for this syndrome. Death of a spouse is a good example of an emotional trigger, though as exemplified in the discussion, it can be any emotional situation. Teasing out the patient's history and the specific precipitation event is an art form.
The autonomic nervous system is implicated here. Catecholamine levels are very elevated in these patients, as opposed to lower levels seen in acute MI patients. Pheochromocytoma and accidental overdose of epinephrine will cause this as well.
The pathophysiology of the event is still being researched. It's postulated that this is all caused by vasospasms of the circulation or direct myocardial injury due to the catecholamine excess. It's presumed that effects occur on micro-circulatory level, and any disruption in blood flow is brief, less than 15-20 minutes, enough to raise serum troponins and cause wall motion abnormality.
The involvement is circumferential, so the ECG findings are more diffuse. EKG changes include ST segment elevation in about 40% of patients. Otherwise T wave inversion is often seen, but is a later development. ST depression is not generally seen in Takotsubo, and would instead indicate a coronary artery occlusion.
Echo findings show a classic, distinctive finding: poor contractility or akineses from the mid-heart to the apex, while the base of the heart is hypercontractile. Also called apical ballooning, the apex can be seen ballooning outward on echocardiograms. This is what is reminiscent of a Japanese clay pot, octopus trap, aka Takotsubo. And yes, the name is most certainly credited to the Japanese.
When a patient presents with an acute cardiac event that looks like Takotsubo, the patients still must undergo coronary angiogram to exclude a coronary occlusion. Cardiac echo and cardiac MRI are used to help diagnose this disease.
Beta blockers and ACE inhibitors are used early on in treatment, but Dr. Sharkey suspects that patients would probably recover without them. The reality is, most of these patients get better. The myocardium, in the setting to Takotsubo, should recover. A process that usually takes one to two weeks. Anti-platelets do not play a role here, but anticoagulants are often given until the myocardium has recovered to prevent a small risk of left ventricular thrombus.
Left ventricular outflow tract obstruction is a complicating factor in Takotsubo. Many of these patients are middle aged to older women, and have basal septal hypertrophy. This exacerbates, the outflow obstruction, which causes hypotension and shock in Takotsubo, 15-20% of the time. The left ventricular outflow obstruction should resolve with the resolution of Takotsubo.
As mentioned, Takotsubo can have a recurrent phenomenon, and remarkably, these patients all recover their heart function. Curiously, the precipitating cause for these patients tends to be emotional.
Though used in the initial treatment, beta blockers are not prescribed long-term for Takotsubo patients. In fact, Dr. Sharkey found that 30% of patients with a Takotsubo event were already on beta blockers, and 80% of those who have had recurrent Takotsubo were already on beta blockers and ACE inhibitors.
Patient presentation: Patients can present with chest discomfort and/or shortness of breath, much like an acute MI patient. They can also present with an acute concern of another nature. Dr. Sharkey gave the example of a patient presenting with a pasteurella multocida infection causing an airway obstruction. The patient's ongoing hypotension led to further work up and diagnosis of Takotsubo.
Takotsubo patients can also be discovered during inpatient stays when incidental ECG wave form changes, troponin elevation, tachycardia, and/or hypotension are noted. About 10% of Takotsubo patient's develop cardiogenic shock. Most survive their ICU stay, even if advanced treatment, like intra-aortic balloon pumps or ECMO are required.
For the critically ill, where beta blocker use is contraindicated in the light hypotension, Dr. Sharkey preferred choice of vasopressin followed by phenylephrine. Fortunately, patients recover from Takotsubo. However, malignant arrhythmias and cardiac arrest can happen. Patients are counseled to present to emergency care if their symptoms ever return.
Thank-you for listening.