Clinical Investigation
Echocardiography and Ventricular Arrhythmias
Tissue Doppler-Derived Left Ventricular Systolic Velocity Is Associated with Lethal Arrhythmias in Cardiac Device Recipients Irrespective of Left Ventricular Ejection Fraction

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Highlights

  • •

    LVEF remains the main, although inadequate, marker of risk for lethal arrhythmias.

  • •

    Tissue Doppler indices might predict lethal arrhythmias better than LVEF.

  • •

    Tissue Doppler-derived systolic velocity (S′) is inversely linked to VT/VF risk.

  • •

    Lower S′ is associated with VT/VF occurrence irrespective of age, gender, and LVEF.

Background

Life-threatening arrhythmias (LTAs) can trigger sudden cardiac death or provoke implantable cardioverter-defibrillator (ICD) discharges that escalate morbidity and mortality. Longitudinal myofibrils predominate in the subendocardium, which is uniquely sensitive to arrhythmogenic triggers. In this study, we test the hypothesis that mitral annular systolic velocity (S′), a simple routinely obtained tissue Doppler index of LV long-axis systolic function, might predict lethal arrhythmias irrespective of left ventricular ejection fraction (LVEF).

Methods

This is a retrospective analysis of data from 302 patients (mean age, 68 years; LVEF, 32%; 77% male; 52% ischemic; 35% primary prevention; and 53% cardiac resynchronization therapy defibrillator [CRT-D]) who were followed up (median, 15 months) at two centers after receipt of an ICD or CRT-D for diverse indications. S′, averaged from tissue Doppler-derived medial and lateral mitral annular velocities, was correlated with the primary outcome of time to sustained ventricular tachycardia (VT) or fibrillation (VF) needing device therapy.

Results

The median S′ was 5.1 (interquartile range, 4.0-6.2) cm/sec and lower in CRT-D than ICD subjects (4.5 [3.8-5.6] cm/sec vs 5.5 [4.8-6.8] cm/sec, P < .001). Fifty-six (19%) subjects had LTA. Each 1 cm/sec higher S′ correlated to a 30% decreased risk of LTA (hazard ratio = 0.70; 95% CI, 0.57-0.87; P = .001) independently of age, sex, β-blocker use, center, ICD use, and LVEF. Adding S′ to the baseline Cox model improved net reclassification (P = .02). An S′ > 5.6 cm/sec was the best cutoff and linked to a 58% lower LTA risk than an S′ ≤ 5.6 cm/sec (95% CI, 0.23-0.85; P = .02).

Conclusions

A higher S′ is associated with a reduced probability of LTA in cardiac device recipients irrespective of LVEF and may have the potential to be used clinically to titrate medical, device, and ablative therapies to mitigate future arrhythmic risk.

Section snippets

Patients

This retrospective study included patients who had device follow-up after transvenous ICD or CRT-D implantation at St. Mary's (June 2004 to December 2012) or King's College (June 2012 to June 2015) Hospital and in whom adequate digitally stored echocardiograms were available and included both lateral and septal mitral annular TDI velocities. Patients with inherited channelopathies were excluded as their arrhythmic risk is not primarily driven by structural myocyte changes.

Of 988 patients who

Baseline Characteristics

Patient characteristics are summarized in Table 1. Of the 302 patients included, 143 (47%) received an ICD and 159 (53%) a CRT-D. Compared with ICD recipients, CRT-D patients were older (70 [61-78] vs 65 [54-74] years, P < .01), had a higher New York Heart Association (NYHA) class (2 [2-3] vs 2 [1-2], P < .001), were less likely to have atrial fibrillation (14% vs 59%, P < .001), and were more likely to have a secondary prevention indication (78% vs 50%, P < .001). They did not differ with

Discussion

To the best of our knowledge, this is the first study to show that S′, a TDI index of LV long-axis systolic function, is associated with the risk of LTA alone in cardiac device recipients independently and incrementally to LVEF. A higher S′ was linked to a lower risk of VT/VF, with an S′ > 5.6 cm/sec associated with a 58% lower hazard. These results were evident in both the ICD and CRT-D subgroups.

Our findings concur with most,12,13,15,16 but not all,17,18 prior analyses. Using speckle-tracking

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    • M.F.B. and D.O.O. are supported by the British Heart Foundation (FS/14/77/30913), London, United Kingdom.

    Conflicts of Interest: None.

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    2020 by the American Society of Echocardiography.