Title: When Is Door-to-Balloon Time Critical? Analysis From the HORIZONS-AMI (Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction) and CADILLAC (Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications) Trials
Date Posted: July 19, 2010
Authors: Brodie BR, Gersh BJ, Stuckey T, et al.
Citation: J Am Coll Cardiol 2010;56:407-413.
Study Question:
What is the impact of door-to-balloon (D2B) time on mortality based on time to presentation and clinical risk in patients with ST-elevation myocardial infarction (STEMI)?
Methods:
The authors assessed the impact of D2B time on mortality in 4,548 patients enrolled in the CADILLAC and HORIZONS-AMI trials.
Results:
Patients with a D2B time of 90 minutes or less had a 1-year mortality of 3.1% versus 4.3% in those with a D2B time greater than 90 minutes. Among patients presenting within 90 minutes of symptom onset, short D2B time was associated with a lower mortality (1.9% vs. 3.8%, p = 0.029), but not in those with a delayed presentation (4.0% vs. 4.6%, p = 0.47). Short D2B times were associated with a similarly relative reduction in mortality in high- and low-risk patients, although the absolute benefit was greater in the highest risk patients.
Conclusions:
D2B time of ≤90 minutes is associated with a lower mortality rate in patients with early presentation, but there is no difference in mortality of patients who present late.
Perspective:
Considerable effort has been expended to ensure rapid re-perfusion in patients with STEMI, although most patients present beyond the 3-hour window where one would anticipate maximal myocardial salvage. This study elegantly demonstrates that maximal benefit is achieved in patients who present early and get reperfused quickly. While marked reductions have been achieved in D2B time nationally, there has been relatively little improvement in time to presentation. Communitywide efforts are needed to reduce time to presentation so that the benefits of early reperfusion can be maximized.
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Title: Cardiac Origins of the Postural Orthostatic Tachycardia Syndrome
Date Posted: July 9, 2010
Authors: Fu Q, VanGundy TB, Galbreath M, et al.
Citation: J Am Coll Cardiol 2010;55:2858-2868.
Study Question:
What is the mechanism of the postural orthostatic tachycardia syndrome (POTS)?
Methods:
Twenty-seven patients (mean age 26 years) with POTS and 16 healthy control subjects (mean age 28 years) underwent comprehensive autonomic function testing, blood volume measurement, and cardiac magnetic resonance imaging. Twenty-five of the POTS patients were re-evaluated after a 3-month exercise program.
Results:
The mean supine and standing heart rates (HRs) were 88 and 114 bpm, respectively, in the POTS patients, and 72 and 89 bpm in the controls. Compared to the controls, the mean blood volume was significantly smaller in the POTS patients (60 vs. 71 ml/kg), as was the mean left ventricular mass (1.26 vs. 1.45 g/kg). There was no evidence of autonomic dysfunction in the POTS patients. Exercise training was associated with significant increases in blood volume and left ventricular mass of 7% and 12%, respectively, a mean decrease in upright HR of 9 bpm, and an improvement in quality of life.
Conclusions:
POTS results from a small heart and low blood volume, not from autonomic dysfunction. Exercise training is an effective therapy for POTS.
Perspective:
The Grinch, a character created by Dr. Seuss, had a heart that was ‘2 sizes too small,’ and, therefore, the authors of this study propose that POTS be referred to as the ‘Grinch Syndrome.’ This interesting study raises the question of whether a small heart also plays a role in another syndrome associated with sinus tachycardia, namely inappropriate sinus tachycardia.
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