1. 2) Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114
Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology
Assessment of Dyssynchrony by Gated Myocardial Perfusion Imaging Does Not Improve Patient Management
Ran Lee, MD (1), Ravi V. Shah, MD (2) and Venkatesh L. Murthy, MD, PhD (1)
1) Frankel Cardiovascular Center, University of Michigan, 1500 E. Medical Center Dr, Ann Arbor, MI
2) Massachusetts General Hospital, 55 Fruit St, Boston, MA 02114
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2. Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology
BACKGROUND
Heart failure is the most common cause for hospitalization in patients older than 65 years old
Despite optimal medical therapy, morbidity and mortality remain high
Mechanical dyssynchrony is prevalent and leads to worsening symptoms and poorer prognosis
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3. Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology
Results
Several trials demonstrate benefit of cardiac resynchronization, leading to guidelines supporting its use in patients with QRS ≥ 150 ms, LBBB morphology, NYHA II-IV symptoms and LVEF ≤ 35% on guideline-directed medical therapy
There are several methods by which to measure dyssynchrony, including electrocardiographic, echocardiographic, and nuclear
Several large randomized echo trials (PROSPECT, EchoCRT) to date have not supported routine use of echocardiographic methods of dyssynchrony imaging in patient selection or decision to implant resynchronization devices
To date, using gated SPECT imaging, phase standard deviation and histogram bandwidth have been used to assess patients who may respond to CRT, in addition to being measures that may be related to hard outcomes such as mortality or arrhythmias
ERNA has been used as well to assess for response to CRT therapy
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4. Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology
Figures
Figure 1: Pressure-Volume Loop with and without Mechanical Dyssynchrony11,12. Right ventricular free wall pacing was used to induce dyssynchrony 12. Atrial pacing was used as a control. In the setting of induced dyssynchrony, stroke volume decreases and end-systolic volume increases while the end-systolic pressure-volume relationship (ESPVR) shifts to the right11.
11. Cheng A, Helm RH, Abraham TP. Pathophysiological mechanisms underlying ventricular dyssynchrony. Europace. 2009; 11: v10-v14.
12. Park RC, Little WC, O'Rourke RA. Effect of alteration of left ventricular activation sequence on the left ventricular end-systolic pressure-volume relation in closed-chest dogs. Circ Res. 1985;57:
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5. Journal of Nuclear Cardiology | Official Journal of the American Society of Nuclear Cardiology
Table
Study
Question
Patients (n)
Inclusion Criteria
Therapy
Primary End Point
P value
MUSTIC-SR (NEJM 2001)34
CRT benefit in HFrEF 58
NYHA III
LVEF <35%
QRS > 150 ms
LVEDd ≥ 60 mm
Active vs. Inactive CRT after implant
6 min walk
<0.001c
MIRACLE (NEJM 2002)8
453
NYHA III-IV
LVEF ≤ 35%
QRS ≥ 130 ms
LVEDd ≥ 55 mm
6MW ≤ 450 m
NYHA, QOL score, 6 min walk
<0.001a
0.001b
0.005c
MIRACLE-ICD (JAMA 2003)35
CRT-D benefit in HFrEF
369
0.007a
0.02b
0.36c
CARE-HF (NEJM 2005)9
814
QRS ≥ 120 ms
LVEDd ≥ 30 mm
CRT vs. optimal medical therapy
Death or hospitalization
HR 0.63; CI ; p<0.001
REVERSE (JACC 2008)22
610
NYHA I-II
LVEF ≤ 40%
HF clinical composite response, hospitalization
0.10d
HR 0.47e p=0.03e
MADIT-CRT (NEJM 2009)23
1820
LVEF ≤ 30%
CRT-D vs. ICD alone
Death or non-fatal HF event
HR 0.66, CI , p=0.001
RAFT (NEJM 2010)36
1798
NYHA II-III
Death, hospitalization for CHF
HR 0.75, CI , p=0.003
8. Abraham WT, Fisher WG, Smith AT, et al. on behalf of the MIRACLE Study Group. Cardiac resynchronization in chronic heart failure. N Engl J Med. 2002;346:
9. Cleland JG, Daubert JC, Erdmann E, et al. on behalf of the Cardiac Resynchronization-Heart Failure (CARE-HF) Study Investigators. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med. 2005; 352:
22. Daubert C, Gold MR, Abraham WT, et al., on behalf of the REVERSE Study Group. Prevention of disease progression by cardiac resynchronization therapy in patients with asymptomatic or mildly symptomatic left ventricular dysfunction: insights from the European cohort of the REVERSE trial. J Am Coll Cardiol. 2009; 54:
23. Moss AJ, Hall WJ, Cannom DS, et al., on behalf of the MADIT-CRT Trial Investigators. Cardiac-resynchronization therapy for the prevention of heart-failure events. N Engl J Med. 2009; 361:
34. Cazeau S, Leclercq C, Lavergne T, et al. Effects of multisite biventricular pacing in patients with heart failure and intraventricular conduction delay, on behalf of the MUSTIC Study Investigators. New Engl J Med. 2001; 344(12):
35. Young JB, Abraham WT, Smith AL, et al. Combined cardiac resynchronization and implantable cardioversion defibrillation in advanced chronic heart failure: the MIRACLE ICD Trial. JAMA. 2003; 289(20):
36. Tang AS, Wells GA, Talajic M, et al. Cardiac-resynchronization therapy for mild-to-moderate heart failure, on behalf of the RAFT Trial Investigators. N Engl J Med. 2010; 363(25):
aNYHA Class Improvement bQOL or Quality of Life Score Improvement c6-minute Walk Improvement dHF clinical composite response eTime to first hospitalization
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CONCLUSIONS
Although imaging methods of dyssynchrony assessment may be useful in research, their clinical role remains unproven
Despite favorable small, single-center studies assessing these techniques, there are no existing high-quality data supporting the use of noninvasive methods of dyssynchrony assessment in patient selection for cardiac resynchronization therapy
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