Effects of dual-chamber pacing on regional myocardial deformation in patients with hypertrophic obstructive cardiomyopathy

Abstract

Background: This study examined the effects of dual-chamber pacing (DDD) on regional myocardial deformation, as determined by echocardiographic strain and strain rate (SR) imaging, in patients with hypertrophic obstructive cardiomyopathy (HOCM). Methods and Results: Fourteen patients (11 men, 3 women; mean age 55±16 years) who had been on long-term DDD (mean period 7.4±2.1 years) underwent strain and SR imaging. Before and after DDD, the peak strain (%) and SR (s-1) during systole were assessed in 8 segments in 4 left ventricular (LV) walls. With DDD turned on, peak strain and SR were significantly increased in the basal anteroseptal (strain -10.2±6.8 to -1.0±6.4, p<0.005; SR -0.76±0.46 to 0.05±0.58, p<0.001) and septal segments (strain -11.2±8.9 to -2.2±7.7, p<0.005; SR -0.85±0.54 to -0.19±0.75, p<0.05), but not in the basal posterior (strain -15.0±13.0 to -13.4±9.2, p=NS; SR -1.37±0.57 to -1.93±0.65, p=NS) and lateral segments (strain -18.1±10.2 to -15.7±5.6, p=NS; SR -1.33±0.68 to -0.84±0.88, p=NS). These findings were associated with a modest, but significant, change in the LV pressure gradient (24±12 mmHg to 14±7 mmHg, p<0.001). Conclusions: In patients with HOCM, DDD appeared to produce myocardial lengthening in the basal septum during systole, which may have implications for the mechanism of reducing LV outflow obstruction during DDD.