Takotsubo cardiomyopathy, or transient left ventricular apical ballooning or broken heart syndrome, is characterized by excessive sympathetic stimulation induced acute coronary vasospasm. A 46-year-old female presented with polyuria and polydypsia and was diagnosed with new-onset diabetes mellitus, treated with insulin and intravenous fluids. During the hospital stay, she complained of an episode of left-sided chest pain and had mildly elevated cardiac enzymes. EKG showed new ST-segment elevation in V2, V3 leads without reciprocal changes. Her coronary angiogram showed no significant coronary artery stenosis, but severe systolic dysfunction and akinesis of the mid-anterior, anteroapical, mid-inferior and inferoapical segments. Further workup was negative except for plasma metanephrine being elevated. MRI of the abdomen showed a right adrenal mass consistent with pheochromocytoma. Surgical resection of the adrenal mass showed evidence of pheochromocytoma and the patient's symptoms were resolved.
A multicenter, double-blind, randomized study was conducted to assess the effect of caffeine on regadenoson stress myocardial perfusion imaging (MPI). Subjects with a high likelihood of coronary artery disease underwent a rest single-photon emission computed tomography MPI on day 1 (MPI-1) and a stress MPI with regadenoson on day 3 (MPI-2). Individuals with ≥1 segment with a reversible defect received double-blind caffeine tablets (200 or 400 mg) or placebo 90 min before a repeat regadenoson stress MPI (MPI-3) on day 5. Overall, 207 subjects completed the study (caffeine 200 mg, n = 70; caffeine 400 mg, n = 71; placebo, n = 66). The mean number of segments with reversible defects decreased from MPI-2 to MPI-3 in the caffeine 200 and 400 mg groups versus no significant change in the placebo group [mean ± standard deviation: −0.61 ± 1.097, −0.62 ± 1.367, and 0.12 ± 0.981, respectively (overall treatment effect, P < 0.001)]. The majority of subjects who received caffeine shifted to a lower ischemia size category from MPI-2 to MPI-3, with no clear pattern observed in subjects who received placebo. For caffeine exposed patients with ≥3 segments with reversible defects at MPI-2, 21/23 had fewer detected at MPI-3. Both the 200 and 400 mg doses of caffeine significantly reduced the number of segments with reversible defects detected by regadenoson stress MPI.
The results of this study will show whether the consumption of caffeine equivalent to 2-4 cups of coffee prior to an MPI study with regadenoson affects the diagnostic validity of stress testing (ClinicalTrials.gov number, NCT00826280).
Ibutilide is a class III antiarrhythmic agent used for the termination of atrial fibrillation and atrial flutter. It mainly affects membrane potassium currents and prolongs the cardiac action potential. This effect is reflected as QT interval prolongation on the surface electrocardiogram. Like other drugs that affect potassium currents, ibutilide is prone to induce a malignant ventricular tachycardia, torsade de pointes. We report four cases of torsade de pointes after administration of ibutilide for pharmacologic cardioversion of atrial fibrillation and atrial flutter; three of these cases required direct current cardioversion for termination of torsade de pointes. All four patients were female. We discuss the risk factors for development of ibutilide-induced torsade de pointes.
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